The Impact of Fertility Rate Changes on Breast Cancer Incidence at the Subnational Level

An inverse association between fertility rates and breast cancer incidence has been observed at the national and global levels. However, few studies have examined this relationship using subnational data. We aimed to determine the correlation between total fertility rates (TFR) and breast cancer incidence across cities in Iran's Razavi Khorasan province between ۲۰۱۴ and ۲۰۱۹. This ecological study utilized age-standardized breast cancer incidence rates and TFRs for ۲۸ regions of Razavi Khorasan province from ۲۰۱۴ to ۲۰۱۹. Pearson correlation coefficients assessed the TFR-incidence correlation annually. Annual percent changes (APCs) in incidence rates were estimated using linear mixed models, unadjusted and adjusted for region-level TFRs. TFR declined province-wide, with the steepest decreases in Bakharz (-۴۵%), Torbat Jaam (-۳۹%), and Torghab & Shandiz (-۳۵%). Breast cancer incidence patterns were heterogeneous across cities, with significantly declining APCs in ۷ regions, including Bajestan (-۹.۸%), Gonabad (-۸.۱%), and Torghab & Shandiz (-۸.۳%). Fertility adjustment had minimal impact on APCs. No significant correlation was observed between TFRs and incidence rates from ۲۰۱۴ to ۲۰۱۹ (correlation coefficients -۰.۱۹۳ to ۰.۱۹۳, p>۰.۰۵). In contrast to national and global trends, declining fertility rates did not correlate with increasing breast cancer incidence across Razavi Khorasan cities from ۲۰۱۴ to ۲۰۱۹. Regional differences may modify the impacts of changing fertility patterns on breast cancer occurrence. Further investigations into this relationship are warranted using robust analytical methods.

کلیدواژه ها:

Breast cancer ، Fertility rates ، Ecological study