Association of allostatic load (AL) and residential segregation with breast biopsy outcomes after screening mammography.

1620 Background: Allostatic Load (AL) and residential segregation have been associated with the risk of breast cancer (BC). However, the independent effects of AL and measures of residential segregation (MRSs) on cancer detection and the false positive (FP) biopsy rate in a screening mammography population have not yet been assessed. Methods: We retrospectively identified women aged ³40 who underwent screening mammography between 1/1/2021-12/31/2021 and subsequent breast biopsy from the Mass General Brigham Biobank. We collected age and self-reported race/ethnicity. Each participant's zip code was geocoded to the corresponding census tract. We computed five MRS indices: Dissimilarity (DD), Isolation (BI), Delta (D), Absolute Centralization (AC), Spatial Proximity (SP). We collected the following biomarkers obtained within two years before the index screen: cardiovascular, metabolic, immunologic, renal lab values. AL was assigned one point for each lab value in the worst quartile and summed (continuous). We collected diagnostic breast imaging and biopsy encounters within 12 months after the index screen. Multiple imputation accounted for missing data. Multivariable logistic regression assessed age, race, AL and each of our MRSs association with cancer detection and FP rates. We applied Rubin's rules to estimate overall odds ratios (OR), confidence intervals (CI), and p-values for all covariates. Results: Of the 418 eligible women, 59.6% (N=249) had an FP biopsy, and 66.3% (N=277) had breast cancer, including cases of ductal carcinoma in situ. On average, women were 62 years old (SD=13); 85.6% White. DD was associated with a reduced risk of benign high-risk lesions (OR=0.69, 95% CI:[0.49-0.95]; p=0.025), and homogeneous, affluent census tracts—whether predominantly Black or White—were similarly protective (OR=0.85, 95% Cl:[0.72, 0.99]; p=0.041). MRS indices were linked to lower benign high-risk outcomes (e.g. SP, OR=0.53, 95% CI:[0.31, 0.91]; p=0.021). Age and race significantly predicted adverse events (AEs). Older age was consistently associated with increased AEs across all models (OR = 1.09, 95% CI:[1.00, 1.18]). Cancer detection also increased with age (OR = 1.20, 95% CI: [1.10, 1.30]; p < 0.001). AL was significantly linked to cancer detection (OR = 1.13, 95% CI:[1.00, 1.28]). Conclusions: Some MRSs are associated with cancer detection and high-risk FP. AL remains associated with these cancer and high-risk FP, even accounting for these segregation measures. These factors may contribute to an increased risk of cancer, highlighting the significance of spatial and socioeconomic influences on screening outcomes. Clinical Relevance Statement: AL may serve as a biomarker to enhance biopsy selection following screen-detected mammographic abnormalities, potentially improving cancer detection rates.