Cancer patients with systemic lupus erythematosus (SLE) may have worse outcomes than those without SLE, given their comorbidities. We examined survival in elderly women with breast cancer (BC) and SLE, and hypothesized that it would be decreased compared to women with BC but without SLE.
We identified BC SLE and BC non-SLE patients in the Texas Cancer Registry, and Surveillance, Epidemiology, and End Results, linked to Medicare claims. Overall survival (OS) was estimated after matching (age and cancer stage), and in multivariable Cox proportional hazards models adjusting for other cancer characteristics, treatment, and comorbidities. Two additional cohorts of women without cancer, with and without SLE, were also studied.
We identified 494 BC SLE cases and 145,517 BC non-SLE, of whom we matched 9708. Women with SLE were less likely to receive radiation, breast-conserving surgery or endocrine therapy. The 8-year OS estimate for women with early BC (stages 0-II) with and without SLE was 52% (95% confidence interval [CI] 45%-59%) and 74% (95% CI 73%-75%) respectively. In the Cox multivariable model, BC SLE had increased risk of death (HR 1.65; 95% CI 1.38 to 1.98). Women with BC SLE also had increased risk of death compared to women with SLE but without cancer (HR 1.42; 95% CI 1.05 to 1.92) after adjusting for SLE severity. Women with SLE and BC received less corticosteroids, antimalarials, and immunosuppressants, after cancer diagnosis than those without cancer.
Systemic lupus is a risk factor for increased mortality in women with early BC.