Neighborhood deprivation on increasing deficit accumulation in older breast cancer survivors and non-cancer controls

Background Neighborhood characteristics can affect aging and health. We tested effects of neighborhood deprivation on deficit accumulation frailty scores in a prospective cohort of breast cancer survivors vs. controls aged 60-98. Methods Newly diagnosed, non-metastatic breast cancer survivors (477) and frequency-matched controls (434) were enrolled from 2010-2023, with up to 5-year follow-up through 2024. Deficit accumulation was measured with a 48-item index (scores 0-1); a clinically meaningful deficit increase was defined by a 0.06 score increase. Neighborhood deprivation was assessed using area deprivation index (ADI) at enrollment census block group and categorized into tertiles. Cause-specific Cox models tested the association between ADI and risk of deficit accumulation increase. Results Participants living in more deprived areas (2nd and 3rd tertiles of ADI) had higher risks of increased deficit accumulation (adjusted hazard ratios [aHR] 1.38 [1.01-1.89; P = .04] and 1.46 [1.07-1.94; P = .01] vs. 1st tertile, respectively). Independent of ADI, being a survivor (vs. control) was associated with greater risk of increased deficit accumulation (aHR = 1.69 [1.32-2.17, P<.001]). There were different patterns of cumulative incidence rates of increased deficit accumulation by ADI survivors treated with chemotherapy (+/- hormonal therapy) living in more vs. less deprived areas had a 20% higher incidence of increased deficit accumulation within 1 year (P = .004), while survivors receiving hormonal therapy alone and non-cancer controls had their most pronounced differences by 4 years (10%; P = .32 and 10%; P = .05, respectively). Conclusions Neighborhood deprivation may increase deficit accumulation, with an apparent acceleration of effects among older breast cancer survivors treated with chemotherapy.