Estimated Excess Mortality from Breast Cancer Among Women in Southeastern Iran, 2014 - 2020

Abstract

Background: Breast cancer poses a critical global and Iranian public health challenge, with pronounced regional and socioeconomic disparities affecting patient outcomes. Quantifying cancer-related survival and characterizing inequalities in survival are key objectives of population-based epidemiology. Objectives: This study aimed to estimate breast cancer-associated excess mortality among women in southeastern Iran using an excess mortality framework that compares observed survival in patients with expected survival derived from general population life tables. Methods: We analyzed registered breast cancer cases at Kerman University of Medical Sciences from 2014 to 2020. Survival probabilities and mean survival times were estimated, and the log-rank test was used to compare survival distributions across groups. The excess mortality rate was estimated by comparing observed and expected deaths. All statistical analyses were performed using R, and P < 0.05 was considered statistically significant. Results: Among the 3,431 women with breast cancer included in the analysis, survival outcomes were significantly better among patients residing in non-provincial-center cities and among those diagnosed with grade 1 tumors. The estimated excess mortality rates at 3, 4, and 5 years of follow-up were 5% (95% CI, -0.409 to 0.522), 6% (95% CI, -0.440 to 0.573), and 7% (95% CI, -0.459 to 0.607), respectively. However, the wide confidence intervals included the null value, indicating that these excess mortality estimates were not statistically significant. Conclusions: Over 6 years of follow-up, women with breast cancer in southeastern Iran experienced lower survival and measurable excess mortality than the general population. Although survival differed by place of residence and tumor grade, the wide confidence intervals around the excess mortality estimates indicate substantial uncertainty. Larger multicenter studies with more comprehensive clinical data are needed to validate these findings and better characterize the determinants of excess mortality in this population.