Poverty in the residential and surrounding counties and its impact on mortality in women with breast cancer.

BACKGROUND

The influence of poverty on cancer outcomes beyond a woman's county of residence remains understudied, despite individuals frequently interacting within a larger ecosocial system.

METHODS

A retrospective cohort study was conducted to investigate whether high poverty in residential and surrounding counties is associated with increased mortality. Women from the National Cancer Institute Surveillance, Epidemiology, and End Results database ≥20 years of age, diagnosed with primary breast cancer between 2005 and 2014, and who survived at least 1 year (N = 36,711) were included. Participants were aggregated by their county of residence and linked to their American Community Survey 5-year poverty estimates. Local Moran's I was used to categorize residential and surrounding county poverty environments as high or low using a mean cutoff. Multivariable-adjusted negative binomial regression was used to evaluate mortality relative risk (MRR) and 95% CIs for the association between residential and surrounding county poverty on all-cause mortality.

RESULTS

Women in high-poverty residential (Hr) counties had a 6% increase in death (MRR = 1.06; 95% CI, 1.01-1.10) compared to women in low-poverty residential counties (Lr). Women surrounded by high-poverty (Hs) counties had a 22% increase in death (MRR = 1.22; 95% CI, 1.13-1.31) compared to women surrounded by low-poverty (Ls) counties. The combined MRR for women in Hr-Hs, Lr-Hs, and Hr-Ls counties was 1.23 (95% CI, 1.13-1.33), 1.25 (95% CI, 1.02-1.51), and 1.08 (95% CI, 0.95-1.21), respectively, when compared to Lr-Ls counties.

CONCLUSION

Poverty in the surrounding counties has a greater impact on mortality among survivors than residential county poverty alone. Incorporating poverty levels from both residential and surrounding counties can improve definitions of high- and low-risk regions after a breast cancer diagnosis.