Abstract PO2-25-08: Role of social isolation and support on all-cause and breast cancer specific mortality among women with breast cancer: The Western New York Exposures and Breast Cancer (WEB) Study

Abstract Background: Studies of associations of social support with mortality among women diagnosed with breast cancer have been inconclusive. Further, there have been little study of related factors such as marital status, housing, and income, nor of differential impact by treatment received (chemotherapy, radiation, or hormonal therapy). Methods: Women with incident, pathologically confirmed invasive breast cancer, stage I-IV, answered a social support questionnaire data (n=1015) in a population-based study, the Western New York Exposures and Breast Cancer (WEB) Study. Patients were queried regarding the number of their close friends, the number of people with whom they lived with, their income, education, and marital status. Hazard ratios (HR) and 95% confidence intervals (CI) for all-cause and breast cancer-specific mortality were estimated with Cox proportional hazards models. Associations were also examined within strata of treatment type received. Results: Median follow up time was 18.5 yrs, 449 died of which 279 deaths were from breast cancer. Out of 1015 patients, 98 patients reported 0-1 friends while 917 reported 2 or more friends. The crude association of social isolation, defined as reporting no or one close friend, was significantly associated with higher all-cause mortality with HR 1.57 (95% CI 1.19-2.07) (p=0.0014). Older age (62 yrs vs. 57 yrs), fewer years of education (12.5 yrs vs. 13.5 yrs), longer smoking history (17 pack years vs. 10.7 pack years), higher percentage of non-white population (15.3% vs. 7.52%), lower income (20.7% vs. 7.2%), living alone (45.9% vs. 21.9%), post-menopausal status (83.7% vs. 70.7%), lower receipt of chemotherapy (32.3% vs. 44.8%), higher receipt of hormone replacement therapy (43.9% vs. 37.0%), high blood pressure (53.6% vs. 33.8%), high blood cholesterol (45.8% vs. 34.1%), more likelihood of being divorced/separated, widowed, never married (20.8% v. 12.8%, 19.8% vs. 15.2%, 13.5% vs. 7.8%) were significantly associated with social isolation. After controlling for these variables, there was no association between social isolation and all-cause mortality, HR 1.14 (95% CI, 0.78-1.66). Being widowed (HR 1.53, 95% CI 1.19-1.95), divorced/separated (HR 1.5, 95% CI 1.14-1.99), having lower income (HR 3.58, 95% CI, 1.89-6.77) and lower education (HR 1.07, 95% CI 1.03-1.12) were associated with higher all-cause mortality. In multivariable analyses, only lower income was associated with higher all-cause mortality (HR 2.44, 95% CI 1.16-5.14). There was no association of social isolation, marital status, income, education, or housing with breast cancer specific mortality. There were also no significant associations of marital status, income, social support, or housing with mortality within strata of treatment received. Conclusions: In this population-based study of women who had been diagnosed with breast cancer, social support, measured as the number of friends the breast cancer patient could call on for assistance, was not associated with either all cause or breast cancer mortality. Higher income was associated with lower mortality. Our study focused on social networks; future studies should also analyze emotional domain of social support, that is, perceived social support: feeling encouraged, shared problem-solving etc., which have higher clinical relevance than structural support. Citation Format: Shipra Gandhi, Jing Nie, Archit Patel, Maurizio Trevisan, Kristopher Attwood, Jo L. Freudenheeim. Role of social isolation and support on all-cause and breast cancer specific mortality among women with breast cancer: The Western New York Exposures and Breast Cancer (WEB) Study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-25-08.