The association between neighborhood socioeconomic status and breast cancer incidence and mortality risk: a large-scale cohort studies systematic review and meta-analysis.

Purpose: Breast cancer (BC) remains one of the leading causes of cancer-related incidence and mortality globally, with growing evidence suggesting that neighborhood socioeconomic status (n-SES) can influence cancer incidence and survival. However, findings across studies remain inconsistent, and the extent to which n-SES impacts BC outcomes has not been comprehensively understood. A thorough systematic review and meta-analysis were conducted to assess the association of neighborhood socioeconomic status n-SES and BC incidence and mortality risk.

Methods: A thorough investigation of existing literature was conducted by applying ISI Web of Science, PubMed/MEDLINE, and Scopus until June 08, 2025. Hazard ratios (HR), along with their respective 95% confidence intervals (CI), were integrated utilizing a random-effects model. A validated approach was utilized for assessing the quality of the studies and identification of publication bias, employing the Newcastle-Ottawa Scale for the assessment of quality, conducting subgroup analyses to identify potential sources of heterogeneity, and applying Egger's regression to detect publication bias and perform sensitivity analyses.

Results: A total of 17 studies with 779,352 adult subjects were found. The results revealed no association of significance among disadvantaged n-SES and BC incidence risk (HR = 1.19; 95% CI 0.86, 1.65; I² = 97.7%; p = 0.300; n = 10). However, the subgroup analysis reveals an association of significance among disadvantaged n-SES status and a decreased BC incidence risk in case-control studies (vs. cohort studies) (HR = 0.81; 95% CI 0.72, 0.92; I² = 0.0%; p = 0.001; n = 2) and for the luminal A cancer sub-type (HR = 0.84; 95% CI 0.73, 0.91; I² = 29.3%; p = 0.012; n = 3). In contrast, the subgroup analysis revealed an significance association between disadvantaged n-SES status and an increased BC incidence for HER2 + (HR = 1.46; 95% CI 1.14, 1.78; I² = 0.0%; p = 0.002; n = 2) or the triple-negative cancer sub-type (HR = 1.39; 95% CI 1.19, 1.69; I² = 41.1%; p < 0.001; n = 4). The results also suggest a significant association between disadvantaged n-SES and a higher BC mortality risk (HR = 1.32; 95% CI 1.16, 1.51; I² = 76.4%; p < 0.001; n = 8). Sensitivity analyses and an evaluation of publication bias revealed no significant association with BC incidence or mortality risk.

Conclusion: Disadvantaged n-SES is identified as a significant element to higher death rates related to BC. By understanding the root causes of inequalities in BC incidence and mortality across different socioeconomic environments, targeted interventions can be tailored to meet the specific needs of vulnerable individuals, ultimately leading toward improved BC outcomes for those at greatest risk.