7229979
Physical Activity and Risk of Endometrial Cancer: A Report from the Shanghai Endometrial Cancer Study
We evaluated the type and amount of physical activity associated with risk of endometrial cancer. In this population-based case-control study, in-person interviews were completed among 832 incident endometrial cancer cases and 846 age-matched controls. Physical activity from exercise, household activities, and transportation was assessed in adolescence and adulthood, as was lifetime occupational activity. Logistic regression was used to estimate adjusted odds ratios (OR) and 95% confidence limits (95% CL). Women reporting exercise participation in both adolescence and adulthood were at nearly a 40% reduced risk (OR, 0.63; 95% CL, 0.42-0.95), compared with women reporting no exercise in either life period. Postmenopausal women who initiated exercise in adulthood were also at reduced risk (OR, 0.76; 95% CL, 0.56-1.02). Reductions in risk were also observed for common lifestyle activities, including household activity (both life periods) and walking for transportation (adulthood). Examination of the independent and combined effect of exercise and lifestyle activities revealed that women with less active lifestyles but who reported exercise were at 35% reduced risk (OR, 0.65; 95% CL, 0.41-1.02), whereas nonexercisers with more active lifestyles were at 40% to 45% reduced risk. These findings suggest that both lifestyle activities of lower intensity (e.g., walking and doing household chores) and intentional exercise can reduce endometrial cancer risk.
19770271
Incidence trends for cancers of the breast, ovary, and corpus uteri in urban Shanghai, 1972–89
Incidence data from the Shanghai (People's Republic of China) Cancer Registry were used to assess the temporal trends of three major female cancers during 1972–89. Rates for cancers of the breast, corpus uteri and, to a lesser extent, ovary rose over the study period. The increases in breast and ovarian cancer were most pronounced among women under age 50, whereas those for corpus uteri cancer were restricted generally to those aged 55 to 69 years. When considered by cohort year of birth, risk of breast and ovarian cancers rose among women born since 1925 and 1935, respectively, but little evidence of cohort effect was apparent for corpus uteri cancer. Potential explanations for these patterns are explored.
25216813
Cancer incidence trends in urban Shanghai, 1972–1994: An update
Incidence rates for a number of cancers in urban Shanghai, China, have been changing markedly. Herein we update the trends using population‐based data from the Shanghai Cancer Registry for 1972–1994. During 1993–1994, cancers of the lung, stomach, and liver were the 3 leading forms among men, with age‐adjusted (world standard) incidence rates of 50.9, 39.2, and 26.5 per 100,000 person‐years, respectively, followed by cancers of the colon (12.4) and esophagus (10.0). Among women, cancers of the breast (27.5), stomach (19.1), and lung (17.7) were the most common tumors, followed by cancers of the colon (11.3) and liver (9.4). Over the 23‐year period, the rate for all cancers combined, excluding non‐melanoma skin cancer, decreased from 247.5 to 215.2 among men and from 173.6 to 154.0 among women. However, trends for individual forms of cancer varied considerably. Rates doubled for cancers of the colon and biliary tract in both sexes, and they increased substantially for cancers of the brain and nervous system, kidney, pancreas, prostate, corpus uteri, female breast, and ovary, and for non‐Hodgkin's lymphoma. Rates for cancers of the lung and rectum changed little. Rates declined by at least one‐half for cancers of the esophagus and cervix, with notable decreases also for cancers of the stomach and liver. Some of these trends may reflect variations in diagnostic or screening practices, although changes in lifestyle and other environmental exposures are likely to play important roles. Further epidemiologic research in China is needed to identify risk factors influencing the cancer incidence trends. Int. J. Cancer 83:435–440, 1999. © 1999 Wiley‐Liss, Inc.
17990352
Comparison of dietary and non-dietary risk factors in overweight and normal-weight Chinese adults.
The aim of the present study was to compare the differences in dietary and non-dietary factors contributing to normal weight and overweight among urban Chinese adults. Two cross-sectional population surveys were carried out in Tianjin, one of the largest cities in China. A total of 2631 subjects aged 25-64 years were selected by random stratified cluster sampling; 398 men and 490 women were overweight, and 886 men and 857 women were of normal weight. The diet was assessed by food weighing plus consecutive individual 3 d food records. Health-related behaviours and anthropometry were assessed. The overweight group had significantly higher mean daily intakes of energy and carbohydrate than the normal-weight group. Overweight men also had significantly higher mean daily intakes of protein and fat than normal-weight men. Age, daily intakes of energy and carbohydrate, and marital status were positively associated with overweight, while occupational and commuting physical activity, as well as smoking, were inversely associated with overweight among both genders. Daily intakes of protein, fat and alcohol were positively related to the incidence of being overweight among men. People with 7-12 years education were more likely to be overweight compared with those with less than 6 years of education. High intakes of energy and carbohydrate among both genders, as well as high intakes of protein and fat among men, and lower levels of occupational and commuting physical activity, being a non-smoker, and partly higher socio-economic status were related to a greater incidence of being overweight in this population.
25624961
Changes in diet and physical activity affect the body mass index of Chinese adults
OBJECTIVE: To examine the relationship between diet, particularly dietary fat intake, and body mass index (BMI).DESIGN: Prospective study of adults who participated in the 1989 and 1991 China Health and Nutrition Survey.SUBJECTS: 3484 adults aged 20–45 at baseline (1989) survey.MEASUREMENTS: Measurement of dietary intake with replicated 24 h dietary recalls. Anthropometric measurements. Measurements of physical activity, smoking habit and socio-economic factors.RESULTS: Change in fat intake was positively associated with change in BMI in men (β=0.00036, P=0.0001), and change in physical activity level was inversely associated with change in BMI in women (β=−0.12, P=0.02). Energy intake, physical activity and major socio-economic factors were related to BMI in cross-sectional analysis.CONCLUSIONS: Diet is becoming an increasingly important determinant of body weight in this population, where fat and energy consumption has been increasing steadily during the past decade.
43355267
Lifestyle and endometrial cancer risk: a cohort study from the Swedish twin registry
Case‐control studies of lifestyle factors have been inconclusive in the study of endometrial cancer, and prospective data are scarce. Our aim was to examine the associations of physical activity, weight and weight change, fruit, vegetable, and alcohol consumption, socio‐economic status, parity and presence of diabetes mellitus with the risk of endometrial cancer in a cohort study. In 1967, 11,659 women in the Swedish Twin Registry, born 1886–1925, answered a 107‐item questionnaire, including questions about diet, physical activity and other lifestyle factors. Complete follow‐up through 1992 was attained through record linkage to the Swedish Cancer and Death Registers. The relative risks for endometrial cancer were estimated in proportional hazards models that adjusted confidence limits for correlated outcomes. We observed 133 incident cases of endometrial cancer in the cohort. There was no clear pattern of risk over strata of alcohol or fruit and vegetable intake, although the data suggest an increased risk with very low fruit and vegetable intake. Increasing physical activity markedly decreased the risk of endometrial cancer (p for trend < 0.01), independently of weight and parity; the risk in the highest quartile, relative to the sedentary category, was 0.2 (95% CI 0.3–0.8). As expected, higher weight in middle age increased the risk (p for trend < 0.01), as did higher weight in early adulthood. Contrary to previous findings, weight gain did not have an effect independent of weight at enrollment. We did not find a genetic component to endometrial cancer. Our results confirm that environmental factors are the most important, especially physical activity, parity, and weight in young and middle age. Int. J. Cancer 82:38–42, 1999. © 1999 Wiley‐Liss, Inc.
37820503
Metabolic abnormalities (hypertension, hyperglycemia and overweight), lifestyle (high energy intake and physical inactivity) and endometrial cancer risk in a Norwegian cohort
Since high energy intake, inactivity, hypertension and diabetes are linked to obesity and an unfavorable hormonal profile, we wanted to test whether energy intake, physical activity, blood pressure and serum glucose are related to the risk of endometrial cancer independent of the body mass index (BMI). A cohort of 24,460 women, aged 20–49 years, attended a Norwegian health screening twice during 1974–1981; they answered questions about diet, physical activity and chronic diseases, and their height, weight, blood pressure and non‐fasting serum glucose were measured. By the end of 1996, during 15.7 years of follow‐up, 130 cases of endometrial carcinomas were identified. The relative risks (RRs) for endometrial cancer were estimated in proportional hazards models including potentially confounding factors. Obese women (BMI ≥ 30 kg/m2) were at 2.6 times increased risk of endometrial cancer compared to normal weight women (BMI < 25 kg/m2) (RR = 2.57, 95%CI = 1.61–4.10). Among overweight women (BMI ≥ 25 kg/m2), non‐fasting serum glucose in the upper quartile vs. in the lower quartile was associated with a 2.4 times increase in risk (RR = 2.41, 95%CI = 1.08–5.37), whereas among obese women, blood pressure above 140/90 mmHg vs. below 140/90 mmHg in both surveys was associated with a 3.5 times increase in risk (RR = 3.47, 95%CI = 1.24–9.70). Especially in women younger than 50 years, high energy intake (5,044–6,401 kJ/day) conferred higher risk compared to low energy intake (< 4266 kJ/day) (RR = 3.40, 95%CI = 1.52–7.60). Increasing recreational activity tended to be protective. Among obese women with non‐sedentary jobs at both screenings, RR declined to 0.18 (95%CI = 0.05–0.62) as the level of sustained occupational activity increased (ptrend = 0.03). Our results suggest that inactivity and high energy intake are major risk factors for endometrial cancer independent of BMI, and that hypertension and relative hyperglycemia are significant markers of risk, especially among the heaviest women. © 2003 Wiley‐Liss, Inc.
21209875
Risk for endometrial cancer in relation to occupational physical activity: A nationwide cohort study in Sweden
Notwithstanding its biologic plausibility, the association between physical activity and endometrial cancer has been analyzed in only a few epidemiological studies. Retrospective assessment of exposure and small sample size often hampers interpretation of published data. We studied risk for endometrial cancer in relation to physical activity at work in a large cohort of Swedish women identified in the nationwide censuses in 1960 and 1970, with jobs that could be consistently classified into one of 4 levels of physical demands. Follow‐up from 1971 through 1989 was accomplished through record linkages. Multivariate Poisson regression models were used to estimate relative risk. The risk for endometrial cancer increased regularly with decreasing level of occupational physical activity (p for trend < 0.001), and was associated more strongly with activity in 1970 than in 1960. In multivariate analyses, adjusted for age at follow‐up, place of residence, calendar year of follow‐up, and social class, the relative risk among women with the same physical activity level in 1960 and in 1970 was 30% higher for sedentary as compared with high/very high activity level; (p for trend = 0.04). The protective effect of physical activity appeared to be confined to women aged 50 to 69, among whom sedentary work was associated with a 60% higher risk than that observed among women estimated to be physically most active. The excess seemed to disappear within 10 years after a change in physical activity level. Although confounding cannot be ruled out in our data, occupational physical activity appears to reduce the risk for endometrial cancer. Int. J. Cancer 76:665–670, 1998.© 1998 Wiley‐Liss, Inc.
40036002
Anthropometry, physical activity, and endometrial cancer risk: results from the Netherlands cohort study.
Although obesity is an established risk factor for endometrial cancer, evidence linking risk to height, weight change since age 20, and physical activity is limited. In this case-cohort study, 62 573 women from The Netherlands Cohort Study on Diet and Cancer were followed up from 1986 to 1995, and 226 endometrial cancer case patients were identified. In Cox proportional hazards analyses, women 175 cm or taller had an increased risk of endometrial cancer compared with those less than 160 cm (rate ratio [RR] = 2.57, 95% confidence interval [CI] = 1.32 to 4.99). Compared with women with a body mass index (BMI; kg/m2) between 20 and 22.9, women with a BMI of 30 or greater had a higher risk (RR = 4.50, 95% CI = 2.62 to 7.72; P(trend)<.001). Moreover, BMI at age 20 and BMI gain since age 20 were positively associated with endometrial cancer risk (P(trend) = .02 and <.001, respectively). Women who spent 90 minutes per day or more doing nonoccupational physical activities had a lower risk (RR = 0.54, 95% CI = 0.34 to 0.85; P(trend) = .002) compared with those who spent less than 30 minutes per day. High BMI and low physical activity were strong and independent risk factors for endometrial cancer.
39320755
Physical Activity and Risk of Endometrial Cancer
In a population-based case-control study of endometrial cancer, we interviewed 268 cases and an equal number of matched controls regarding physical activity at work and outside of work. We also obtained self-ratings of overall physical activity levels. The results showed that nonretired women holding sedentary jobs or those reporting sedentary life-styles were at somewhat increased risk of endometrial cancer. The associations remained unchanged after adjustment for caloric intake and body mass index. Although an effect of physical inactivity on endometrial cancer risk is biologically plausible, our results show some inconsistencies, such as a lack of elevation in risk among women who were physically inactive outside of work. (Epidemiology 1993;4:342–349)
12484790
Life‐long physical activity and cancer risk among Finnish female teachers
This cohort study on Finnish female teachers of physical education (PE) and languages (L) was performed as an attempt to evaluate the importance of physical activity as a risk determinant of cancer, PE representing a physically active and L a less active subcohort. All the PE and L teachers graduating from 1920 onwards were obtained from four registers compiled from 1958–73 supplemented by an extension cohort drawn from the union membership register 1984–91 (in total 1,499 PE and 8,619 L teachers). Results of a questionnaire to representative samples of L and PE teachers did not reveal any major intergroup differences in social status, general health status, nutrition, maturation history, reproductive history, consumption of alcohol, smoking, or diet. However, the PE teachers reported higher life-long physical activity values than the L teachers. During the follow-up period 1967–91, the number of cancer cases totalled 108 for the PE and 513 for the L teachers. Expected numbers of cancer cases were calculated on the basis of national incidence figures, and the standardized incidence ratios (SIRs) were defined as ratios of observed and expected numbers of cases. The SIR for total cancers was 1.1 for the PE and 1.2 for the L teachers. In both teacher groups the SIRs for cancers of the breast, endometrium, ovary and colon were similarly elevated and the SIR for cervical cancer was reduced. There was an increased SIR for lung cancer (1.4) and skin melanoma (2.0) in the PE but not in the L teachers (0.5 and 0.9, respectively). For cancers of the stomach, rectum, pancreas and kidney, the SIR for the PE teachers was less than one-half of that for the L teachers. Similarly, the SIR for breast cancer at premenopausal age was lower among the PE than L teachers. None of the differences between the SIRs for the PE and L teachers were statistically significant. The results suggest that the potential protective effect of physical activity, if any, is so small that a larger cohort of physically active women would be needed to demonstrate it.
1115179
Selected physical activities and the risk of endometrial cancer.
The relationship between various indicators of physical activity and endometrial cancer risk was analysed using data of a case-control study conducted in 1988-1991 in Switzerland and Italy on 274 histologically confirmed cases and 572 controls admitted to hospital for acute, non neoplastic, non hormone-related diseases. Using a self-rated assessment of total physical activity, there was a systematic tendency for the cases to report more frequently 'low' or 'very low' physical activity. The relative risks were similar for 'very high' or 'moderately high' physical activity, but increased in the two lowest levels, with point estimates, in various decades of age, between 1.3 and 2.3 for 'moderately low' and over 2.5 for 'very low' physical activity. Although the association was apparently stronger at older ages, all the trends in risk were significant. Allowance for major identified potential distorting factors, including body mass index and a measure of total energy intake, could explain only in part the association, and the inverse trends in risk remained statistically significant. When selected types of physical activity were analysed, no association was observed with climbing stairs or walking, but the risk estimates for the lowest level of activity was over 4 for housework, and between 1.5 and 1.9 for sport and leisure and occupational activity. Thus, the present findings suggest that a moderate or high physical activity is an indicator of reduced endometrial cancer risk, although this observation still requires epidemiologic confirmation and clearer definition from a pathogenic point of view.
16062929
Past and present physical activity and endometrial cancer risk.
We examined the relation between physical activity and endometrial cancer using data from a multicentre case-control study involving 405 endometrial cancer cases and 297 population controls. Estimates of recreational (i.e. active sport, walks and hikes) and nonrecreational activity (i.e. house cleaning, climbing stairs and walking or standing on the job) were obtained using interview information. After adjustment for age, study area, education, parity, years of use of oral contraceptives, years of use of menopausal oestrogens and cigarette smoking, recent recreational inactivity was associated with increased risk (RR = 1.9 for lowest vs highest tertile). Similarly, recent nonrecreational inactivity was associated with increased risk (RR = 2.2 for lowest vs highest tertile). Further adjustment for body mass and nonrecreational activity attenuated the association between risk and recent recreational inactivity (RR = 1.2; 95% CL = 0.7-2.0) but adjustment for body mass and recreational activity did not alter the association between risk and recent nonrecreational inactivity (RR = 2.0; 95% CL = 1.2-3.1). To evaluate the relation between risk and sustained inactivity, we simultaneously examined activity levels at three periods (RR i.e. age 20-29, age 30-39 and recently) in women age 50 and older. After adjustment for potential confounders and body mass, risk was elevated among women who were always recreationally inactive (RR = 1.5 for always active vs always inactive) and among women who were always nonrecreationally inactive (RR = 1.6 for always active vs always inactive). This study suggests that physically inactive women may be at increased risk of endometrial cancer because they are more likely to be overweight or obese. Our data also suggest that inactivity per se may be associated with an increased risk of endometrial cancer. However, we cannot rule out the possibility that our results, particularly those for nonrecreational activity, reflect unmeasured confounding factors. Future studies should attempt to obtain more detailed assessments of physical activity, including the intensity with which an individual engaged in an activity and the actual time involved in exertion.
29139835
Recreational physical activity and endometrial cancer risk.
To investigate the association between recreational physical activity and endometrial cancer risk, a population-based case-control study was conducted in Washington State. The study included 822 incident cases of endometrial cancer diagnosed between 1985 and 1991 and 1,111 randomly selected population-based controls. Detailed information on recreational physical activities as well as other endometrial cancer risk factors was obtained in structured, in-person interviews. Unconditional logistic regression, adjusted for age, county, energy intake, unopposed estrogen use, income, and, in separate models, body mass index (kg/m(2)), was used to estimate the odds ratios and their 95% confidence intervals, relating endometrial cancer to each level of physical activity. A greater proportion of controls (49.3%) than cases (40.5%) reported doing regular exercise (compared with no exercise: adjusted odds ratio = 0.62, 95% confidence interval: 0.51, 0.76) in the 2-year period prior to diagnosis date. There was little evidence of a trend of decreasing risk with increasing duration or intensity of recreational physical activities. These results provide support for an association between the lack of recent recreational physical activity and endometrial cancer risk. However, the absence of a difference by duration or intensity levels and the inconsistent results from other studies suggest caution before interpreting this association as causal.
235409
Effect of adiposity and fat distribution on endometrial cancer risk in Shanghai women.
The authors conducted a population-based case-control study of 832 endometrial cancer cases and 846 frequency-matched controls in Shanghai, China (1997-2001), to examine the association of overall adiposity and body fat distribution with disease risk. Overall adiposity was estimated using weight and body mass index (BMI); upper body fat distribution was evaluated using waist circumference and waist:hip ratio. Overall and upper-body obesity were both associated with an elevated risk of endometrial cancer. Adjusted odds ratios and 95% confidence intervals for highest-versus-lowest quartile comparisons were 2.6 (95% confidence interval (CI): 2.0, 3.5) for weight, 2.9 (95% CI: 2.2, 3.9) for BMI, 4.7 (95% CI: 3.4, 6.4) for waist circumference, and 3.5 (95% CI: 2.6, 4.8) for waist:hip ratio. The positive associations with weight and BMI vanished after results were controlled for waist circumference, while associations with waist circumference and waist:hip ratio persisted after adjustment for BMI. The positive association with upper-body obesity was more pronounced among younger women, women who had never used oral contraceptives, and women with a history of diabetes mellitus (p for multiplicative interaction < 0.05). Upper-body obesity was related to increased risk among women with low BMI. These results suggest that obesity, particularly upper-body fat deposition, is associated with an increased risk of endometrial cancer.
38692026
Compendium of physical activities: an update of activity codes and MET intensities.
We provide an updated version of the Compendium of Physical Activities, a coding scheme that classifies specific physical activity (PA) by rate of energy expenditure. It was developed to enhance the comparability of results across studies using self-reports of PA. The Compendium coding scheme links a five-digit code that describes physical activities by major headings (e.g., occupation, transportation, etc.) and specific activities within each major heading with its intensity, defined as the ratio of work metabolic rate to a standard resting metabolic rate (MET). Energy expenditure in MET-minutes, MET-hours, kcal, or kcal per kilogram body weight can be estimated for specific activities by type or MET intensity. Additions to the Compendium were obtained from studies describing daily PA patterns of adults and studies measuring the energy cost of specific physical activities in field settings. The updated version includes two new major headings of volunteer and religious activities, extends the number of specific activities from 477 to 605, and provides updated MET intensity levels for selected activities.
22420722
Reproducibility and validity of the Shanghai Women's Health Study physical activity questionnaire.
In this investigation, the authors evaluated the reproducibility and validity of the Shanghai Women's Health Study (SWHS) physical activity questionnaire (PAQ), which was administered in a cohort study of approximately 75,000 Chinese women aged 40-70 years. Reproducibility (2-year test-retest) was evaluated using kappa statistics and intraclass correlation coefficients (ICCs). Validity was evaluated by comparing Spearman correlations (r) for the SWHS PAQ with two criterion measures administered over a period of 12 months: four 7-day physical activity logs and up to 28 7-day PAQs. Women were recruited from the SWHS cohort (n = 200). Results indicated that the reproducibility of adolescent and adult exercise participation (kappa = 0.85 and kappa = 0.64, respectively) and years of adolescent exercise and adult exercise energy expenditure (ICC = 0.83 and ICC = 0.70, respectively) was reasonable. Reproducibility values for adult lifestyle activities were lower (ICC = 0.14-0.54). Significant correlations between the PAQ and criterion measures of adult exercise were observed for the first PAQ administration (physical activity log, r = 0.50; 7-day PAQ, r = 0.62) and the second PAQ administration (physical activity log, r = 0.74; 7-day PAQ, r = 0.80). Significant correlations between PAQ lifestyle activities and the 7-day PAQ were also noted (r = 0.33-0.88). These data indicate that the SWHS PAQ is a reproducible and valid measure of exercise behaviors and that it demonstrates utility in stratifying women by levels of important lifestyle activities (e.g., housework, walking, cycling).
25020068
Case–control study of diabetes, obesity, physical activity and risk of endometrial cancer among Mexican women
AbstractObjectives: Obesity, hypertension and diabetes are closely associated with endometrial cancer (EC). This study evaluates the relationship between diabetes and risk of EC on the basis of obesity.
Methods: A case–control study was carried out in Mexico City from 1995 to 1997. Eighty-five histologically confirmed cases were compared with 668 population-based controls obtained through frequency matching. Diabetes status, weight, height and other factors were determined through personal interviews among both cases and controls.
Results: Compared to women without diabetes, those with diabetes had an adjusted odds ratio of 3.6 (95% CI = 1.7, 7.4) for EC. This association was modified by body mass index (p interaction < 0.001). Compared to non-overweight and non-diabetic women, non-overweight (OR = 3.9, 95% CI = 0.88, 18.0) and overweight (OR = 5.9, 95% CI = 1.6, 21.1) diabetic women had a non-significant elevated risk of EC. However, elevated risk estimates were observed for obese diabetic women (OR = 8.0, 95% CI = 2.8, 22.7).
Conclusions: Our results strongly suggest an interaction effect between obesity and diabetes that significantly increases the risk of EC. This, in turn, may explain the growing number of new EC cases recently observed in developing countries with reduced birth rates and an increased incidence of both obesity and diabetes mellitus.
8795807
Obesity, endogenous hormones, and endometrial cancer risk: a synthetic review.
Endometrial cancer is a disease of the affluent, developed world, where epidemiological studies have shown that > or =40% of its incidence can be attributed to excess body weight. An additional proportion may be because of lack of physical activity. Alterations in endogenous hormone metabolism may provide the main links between endometrial cancer risk, and excess body weight and physical inactivity. Epidemiological studies have shown increased endometrial cancer risks among pre- and postmenopausal women who have elevated plasma androstenedione and testosterone, and among postmenopausal women who have increased levels of estrone and estradiol. Furthermore, there is evidence that chronic hyperinsulinemia is a risk factor. These relationships can all be interpreted in the light of the "unopposed estrogen" hypothesis, which proposes that endometrial cancer may develop as a result of the mitogenic effects of estrogens, when these are insufficiently counterbalanced by progesterone. In our overall synthesis, we conclude that development of ovarian hyperandrogenism may be a central mechanism relating nutritional lifestyle factors to endometrial cancer risk. In premenopausal women, ovarian hyperandrogenism likely increases risk by inducing chronic anovulation and progesterone deficiency. After the menopause, when progesterone synthesis has ceased altogether, excess weight may continue increasing risk through elevated plasma levels of androgen precursors, increasing estrogen levels through the aromatization of the androgens in adipose tissue. The ovarian androgen excess may be because of an interaction between obesity-related, chronic hyperinsulinemia with genetic factors predisposing to the development of ovarian hyperandrogenism.
10384470
Moderate-intensity physical activity and fasting insulin levels in women: the Cross-Cultural Activity Participation Study.
OBJECTIVE
The purpose of this study was to determine the association between moderate-intensity physical activity (PA) and fasting insulin levels among African-American (n = 47), Native American (n = 46), and Caucasian women (n = 49), aged 40-83 years, enrolled in the Cross-Cultural Activity Participation Study. Associations by race/ethnicity, levels of central obesity, and cardiorespiratory fitness were also examined.


RESEARCH DESIGN AND METHODS
Physical activity scores were obtained from detailed PA records that included all PA performed during two consecutive 4-day periods scheduled 1 month apart. Using MET intensity (the associated metabolic rate for a specific activity divided by a standard resting metabolic rate), PA was expressed as MET-min (the product of the minutes for each activity times the MET intensity level) per day of energy expended in moderate (3-6 METs) and moderate/vigorous (> or = 3 METs) PA. Fasting insulin levels were determined by radioimmunoassay. Data were analyzed by multiple linear regression analysis.


RESULTS
After adjusting for race/ethnicity, age, educational attainment, and site, an increase of 30 min of moderate-intensity PA was associated with a 6.6% lower fasting insulin level (P < 0.05). The association was similar among races/ethnicities, centrally lean and centrally obese women, and women with low and high cardiorespiratory fitness levels.


CONCLUSIONS
These findings lend support to the 1995 Centers for Disease Control and Prevention and American College of Sports Medicine recommendations for an accumulation of 30 min/day in moderate-intensity PA. They also contribute to the growing literature suggesting that moderate amounts of PA have a significant role in reducing the burden of hyperinsulinemia and diabetes among ethnic populations at highest risk for these conditions.
37778765
Intensity and amount of physical activity in relation to insulin sensitivity: the Insulin Resistance Atherosclerosis Study.
CONTEXT
Exercise training is associated with improved insulin sensitivity (SI), but the potential impact of habitual, nonvigorous activity is uncertain.


OBJECTIVE
To determine whether habitual, nonvigorous physical activity, as well as vigorous and overall activity, is associated with better SI.


DESIGN
A multicultural epidemiologic study.


SETTING
The Insulin Resistance Atherosclerosis Study, conducted in Oakland, Calif; Los Angeles, Calif; the San Luis Valley, Colo; and San Antonio, Tex.


PARTICIPANTS
A total of 1467 men and women of African American, Hispanic, and non-Hispanic white ethnicity, aged 40 to 69 years, with glucose tolerance ranging from normal to mild non-insulin-dependent diabetes mellitus.


MAIN OUTCOME MEASURE
Insulin sensitivity as measured by an intravenous glucose tolerance test.


RESULTS
The mean SI for individuals who participated in vigorous activity 5 or more times per week was 1.59 min(-1) x microU(-1) x mL(-1) x 10(-4) (95% confidence interval [CI], 1.39-1.79) compared with 0.90 (95% CI, 0.83-0.97) for those who rarely or never participated in vigorous activity, after adjusting for potential confounders (P<.001). When habitual physical activity (estimated energy expenditure [EEE]) was assessed by 1-year recall of activities, the correlation coefficient between SI and total EEE was 0.14 (P<.001). After adjustment for confounders, vigorous and nonvigorous levels of EEE (metabolic equivalent levels > or = 6.0 and <6.0, respectively) were each positively and independently associated with SI (P< or =.01 for each). The association was attenuated after adjustment for the potential mediators, body mass index (a measure of weight in kilograms divided by the square of the height in meters), and waist-to-hip ratio. Results were similar for subgroups of sex, ethnicity, and diabetes.


CONCLUSIONS
Increased participation in nonvigorous as well as overall and vigorous physical activity was associated with significantly higher SI. These findings lend further support to current public health recommendations for increased moderate-intensity physical activity on most days.
5178718
Effect of exercise on serum estrogens in postmenopausal women: a 12-month randomized clinical trial.
Elevated circulating estrogens and a sedentary lifestyle increase risk for breast cancer. The effect of exercise on circulating estrogens in sedentary postmenopausal women is unknown. The objective of this study was to examine the effects of a 12-month moderate-intensity exercise intervention on serum estrogens. We randomly assigned 173 sedentary, overweight (body mass index > 24.0 kg/m(2), body fat > 33%), postmenopausal women, ages 50-75 years, not using hormone therapy, living in the Seattle, Washington, area for the next year, and willing to be randomly assigned to an exercise intervention or stretching control group. The exercise intervention included facility and home-based exercise (45 min, 5 days/week moderate intensity sports/recreational exercise). A total of 170 (98.3%) women completed the study with exercisers averaging 171 min/week of exercise. After 3 months, exercisers experienced declines in estrone, estradiol, and free estradiol of 3.8, 7.7, and 8.2%, respectively, versus no change or increased concentrations in controls (P = 0.03, 0.07, and 0.02, respectively). At 12 months, the direction of effect remained the same, although the differences were no longer statistically significant. The effect was limited to women who lost body fat: women whose percentage of body fat [by dual energy x-ray absortiometry (DEXA)] decreased by >/==" BORDER="0">2% had statistically significant (comparing exercisers versus controls) decreases at 12 months of 11.9, 13.7, and 16.7% for serum estrone, estradiol, and free estradiol, respectively. We concluded that a 12-month moderate-intensity exercise intervention in postmenopausal women resulted in significant decreases in serum estrogens. The association between increased physical activity and reduced risk for postmenopausal breast cancer may be partly explained by effects on serum estrogens.
6416004
Diet, body size, physical activity, and the risk of endometrial cancer.
Endometrial cancer is associated with increased weight and body size, diabetes, and other conditions that may result from an excess in calories or lack of physical activity. Although a few studies have explored the effect of dietary constituents on the risk of endometrial cancer, the nature of the joint association of these constituents and obesity, energy intake, or energy expenditure with risk is unknown. A population-based case-control study was conducted in Hawaii to examine the association of diet, body size, and physical activity with the risk of endometrial cancer. Subjects included 332 histologically confirmed, primary endometrial cancer cases and 511 controls identified between 1985 and 1993. Cases and controls were residents of Oahu, Hawaii who were between 18 and 84 years of age and were from one of the following ethnic groups: Japanese, Caucasian, Native Hawaiian, Filipino, and Chinese. Cases were identified through the Hawaii Tumor Registry and matched to the controls on age (+/-2.5 years) and ethnicity. In-person interviews, conducted in the subjects' homes, included dietary, reproductive, menstrual, and medical histories and use of exogenous hormones, physical activity, and other lifestyle variables. Weight, girth, and skinfold measurements were taken at the time of the interview. We found a strong dose-response relation of increased body size to the development of endometrial cancer after adjustment for energy intake. The odds ratio (OR) for endometrial cancer among women in the highest quartile of body mass index (BMI; kg/m2) was more than four times that among women in the lowest quartile. Waist, hip, midarm, and wrist girths were positively associated with the estimated risk of endometrial cancer after adjustment for total calories and other nondietary risk factors, although the trends in the ORs were attenuated after adjustment for BMI. Physically active women had a modest reduction in their risk of disease compared with inactive women. Cases consumed a greater percentage of their calories from fat and a lower percentage of their calories from carbohydrates than did controls. Adjustment for BMI reduced the ORs for the highest compared with the lowest quartile of fat calorie intake from 2.0 (95% confidence interval, 1.3-3.2) to 1.6 (95% confidence interval, 1.0-2.6), suggesting that part of the association is explained by obesity. There was a differential effect of fat on endometrial cancer according to BMI. For all components of fat, the associations with endometrial cancer were either minimal or absent among leaner women (i.e., those with BMI below the median), whereas, among more obese women, two-fold differences in risk were observed between women above and below the median of fat intake. Foods that are high in fat and cholesterol, such as red meat, margarine, and eggs, were positively associated with endometrial cancer, whereas cereals, legumes, vegetables, and fruits, particularly those high in lutein, were inversely associated. These findings suggest that women who avoid being overweight and who consume a diet low in plant and animal fats and high in complex carbohydrates are at a reduced risk of endometrial cancer.
10951821
Physical activity and risk of endometrial cancer in a prospective cohort study (United States)
Objective: To examine the physical activity and endometrial cancer relationship in a prospective study of US women enrolled in the Breast Cancer Detection Demonstration Project (BCDDP) Follow-up Study. Methods: We assessed past-year physical activity of all types in 23,369 women who returned the baseline questionnaire (1987–1989) and had no prior hysterectomy and/or endometrial cancer. Cox proportional hazards models were used to estimate age, education, and parity-adjusted rate ratios (RR) and 95% confidence intervals (CI) for the 253 confirmed endometrial cancer cases identified during an average 8.2 years of follow-up (ending 1995–1998). Results: There were no dose–response relationships with either total or vigorous physical activity; however, compared to the lowest total activity quartile, the higher four quartiles had a non-significantly lower risk (RR = 0.8, CI = 0.6–1.0). The association with moderate activity varied with follow-up time: RRs (CI) for a 1 h increase in daily moderate activity within 2-year intervals of follow-up (≤2, 2.1–4.9, 5.0–8.0, >8 years) were 1.1 (1.0, 1.2), 1.0 (0.9, 1.1), 1.0 (0.9, 1.1), 1.0 (0.9, 1.1), and 0.8 (0.7, 1.0), respectively. Conclusion: These data suggest that recent physical activity is not strongly related to the risk of endometrial cancer, and that prolonged exposure and longer follow-up may be necessary.
33129738
American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention: Reducing the Risk of Cancer with Healthy Food Choices and Physical Activity
The American Cancer Society (ACS) has set aggressive challenge goals for the nation to decrease cancer incidence and mortality—and to improve the quality of life of cancer survivors—by the year 2015.
41013686
Physical activity and postmenopausal endometrial cancer risk (Sweden)
AbstractObjectives:To examine the hypothesis that sedentary women have an increased risk of endometrial cancer compared to physically active women.
Methods:This is a population-based case–control study in the entire Swedish female population aged 50–74 years in 1994–1995. We obtained self-reported information on leisure-time physical activity during childhood, at ages 18–30, and recently from 709 incident case women with endometrial cancer and 3368 population controls. Occupational physical activity was estimated through record linkage to the Swedish census data from 1960, 1970, 1980, and 1990. Odds ratios (OR) and 95% confidence intervals (CI) were calculated for different activity levels by multivariate logistic regression, taking into account potential confounders.
Results:Comparing lowest to highest (reference) levels of physical exercise, we observed statistically significant associations with risk of endometrial cancer for leisure-time activity at age 18–30 years (multivariate OR = 1.4; 95% CI = 1.0–1.8; p for trend 0.01) and in recent years (multivariate OR=1.3; 95% CI = 1.0–1.7; p for trend 0.01). We found similar associations comparing lowest to highest (reference) levels of occupational activity assessed at the censuses in 1980 (multivariate OR = 1.4; 95% CI = 1.0–1.9; p for trend 0.03) and 1990 (multivariate OR = 1.3; 95% CI = 0.9–1.9, p for trend 0.05), but a less consistent association with censuses in 1960 and 1970. The increased risk associated with low level of occupational physical activity was confined to women who were not obese and to women who were smokers.
Conclusion:Our data, in conjunction with past epidemiological studies, indicate that both occupational and leisure-time physical activity may reduce the risk for postmenopausal endometrial cancer.
7301797
Lifetime physical activity and breast cancer risk in the Shanghai Breast Cancer Study
Overall physical activity in adolescence and adulthood, and changes in activity over the lifespan were analysed by in-person interviews among 1459 women newly diagnosed with breast cancer and 1556 age-matched controls in urban Shanghai. Physical activity from exercise and sports, household, and transportation (walking and cycling) was assessed in adolescence (13–19 y) and adulthood (last 10 y), as was lifetime occupational activity. Logistic regression was used to estimate odds ratios (OR) and 95% confidence limits (OR (95% CL)) while controlling for confounders. Risk was reduced for exercise only in adolescence (OR = 0.84 (0.70–1.00)); exercise only in adulthood (OR = 0.68 (0.53–0.88)), and was further reduced for exercise in both adolescence and adulthood (OR = 0.47 (0.36–0.62)). Graded reductions in risk were noted with increasing years of exercise participation (OR1–5 yrs= 0.81 (0.67–0.94); OR6–10 yrs= 0.74 (0.59–0.93); OR11–15 yrs= 0.55 (0.38–0.79); OR16 + yrs= 0.40 (0.27–0.60);Ptrend,< 0.01). Lifetime occupational activity also was inversely related to risk (Ptrend< 0.01). These findings demonstrate that consistently high activity levels throughout life reduce breast cancer risk. Furthermore, they suggest that women may reduce their risk by increasing their activity levels in adulthood. © 2001 Cancer Research Campaign
40960291
Influence of Physical Activity in Different Age and Life Periods on the Risk of Breast Cancer
We conducted a population-based case-control study of 1,237 incident breast cancer cases and 1,241 controls in Alberta between 1995 and 1997 to examine the effect of physical activity performed at different ages and life periods on breast cancer risk. In this study, we measured all types of physical activity done throughout life with a questionnaire developed and tested specifically for this study. We found that breast cancer risk was most associated with a risk reduction for activity done later in life, particularly between menopause and the reference year, for which we observed an odds ratio of 0.70 (95% confidence interval = 0.52–0.95). We also stratified the study participants into four categories according to their patterns of physical activity performed before and after menopause. For the women who sustained physical activity throughout life vs those who were never active, we found an odds ratio of 0.58 (95% confidence interval = 0.41–0.83). This study suggests that sustained activity throughout life and particularly activity done later in life may have the most benefit in reducing breast cancer risk.
15026137
Physical activity and breast cancer risk in women aged 20-54 years.
BACKGROUND/METHODS
Although several studies have suggested that physical activity is associated with a decreased risk of breast cancer, such a decrease has not been found consistently, perhaps because physical activity was assessed in different ways and for restricted periods. Few studies have assessed the risk of breast cancer in relation to lifetime physical activity. We used data from a population-based, case-control study, including 918 case subjects (aged 20-54 years) and 918 age-matched population control subjects, to examine associations between breast cancer risk and physical activity at ages 10-12 years and 13-15 years, lifetime recreational activity, and title of longest held job.


RESULTS
Women who were more active than their peers at ages 10-12 years had a lower risk of breast cancer (odds ratio [OR] = 0.68; 95% confidence interval [CI] = 0.49-0.94). Women who had ever engaged in recreational physical activity had a reduced risk of breast cancer compared with inactive women (OR = 0.70; 95% CI = 0.56-0.88). Neither very early recreational activity (before age 20 years) nor recent activity (last 5 years) was associated with a greater reduction in risk than recreational activity in the intermediate period. Furthermore, women who started recreational activities after age 20 years and women who started earlier and continued their activities throughout adult life experienced a similar reduction in risk. Lean women, i.e., women with a body mass index (weight in kg/[height in m](2)) less than 21. 8 kg/m(2), appeared to have a lower risk associated with recreational physical activity than women with a body mass index greater than 24.5 kg/m(2) (OR = 0.57 [95% CI = 0.40-0.82] and OR = 0. 92 [95% CI = 0.65-1.29], respectively).


CONCLUSIONS
Our findings support the hypothesis that recreational physical activity is associated with a decreased risk of breast cancer. Physical activity in early or recent life does not appear to be associated with additional beneficial effects.