Evidence reported by retrospective investigators and our own prospective studies suggest the existence of psychobiological factors which precede the clinical appearance of cancer by many years. We obtained an extensive, unique data base (psychological, psychosocial, physiological, medical, familial, and genetic) on a cohort of 1,337 medical students and have followed them prospectively for 2 to 36 years. Now for the most part between the ages of 43 and 66, over 100 have already had some type of cancer, an all have reached the age at which cancer incidence is rising rapidly. It is our aim: 1. To continue collecting data concerning the health status of subjects and their parents, with special attention to the occurrence of cancer. 2. To continue reduction and analysis of Precursors Study data by domain in order to discover the most important sources of variance. 3. To derive "profiles" or "patterns" associated with the later development of cancer across the psychological and behavioral data domains already reduced. 4. To further investigate the association between Rorschach content in young adulthood and future cancer, with special reference to a) the use of specific words and to b) the expression of interrelationships between two or more human or animal figures in subject's responses. 5. To make both retrospective and prospective studies of eating habits and diet (in medical school and at successive 5-year follow-ups) of subjects developing future cancer compared with those of classmates remaining healthy, or developing other disorders. These data are on hand. 6. To organize and carry out a psychosocial and medical midlife survey of living subjects. Several appropriate standard as well as experiments psychological measures will be included in the packet; the results would serve both as current status (outcome) measures as well as potential predictors of later health and life events.