Social Integration, Marital Status, and Ovarian Cancer Risk: A 20-Year Prospective Cohort Study

Objective Low social integration and divorce/widowhood are chronic psychosocial stressors that may affect health. When assessed after cancer diagnosis, they have been associated with poorer survival, but their role in cancer development, particularly ovarian cancer (OvCA), is less understood. We investigated whether social integration and marital status were related to OvCA risk in a large population-based study. Methods Women from the Nurses' Health Study completed the Berkman-Syme Social Network Index and reported their marital status every 4 years starting in 1992 (N = 72,206), and were followed up until 2012 (20-year follow-up period). Multivariate Cox regression models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) of OvCA risk, considering relevant potential confounders, in lagged analyses whereby psychosocial indicators were assessed 4 to 8 years (n = 436 cases) and 8 to 12 years (n = 306 cases) before diagnosis to account for the effects of prediagnostic symptoms on social measures. Secondary analyses evaluated the stability of and cumulative exposure to these social factors on OvCA risk. Results Being socially isolated versus integrated was related to an increased OvCA risk 8 to 12 years later (HR = 1.51, 95% CI = 1.07-2.13), but not 4 to 8 years later. Compared with married women, OvCA risk was significantly higher in widowed but not in separated/divorced individuals, with both time periods (e.g., 8-12 years later: HR^widowed = 1.57 [95% CI = 1.15-2.14] versus HR^{separated/divorced} = 1.13 [95% CI = 0.74-1.72]). Estimates were comparable or stronger when investigating stability in and cumulative effects of social indicators. Conclusions Results suggest higher OvCA risk among socially isolated and widowed women, particularly when such psychosocial stressors were experienced a decade before diagnosis or were sustained over time.