Evaluation of urban-rural difference in breast cancer mortality among Chinese women during 1987-2021: A hierarchical age-period-cohort analysis

Background: Breast cancer mortality varies in urban and rural areas in China. Studies have reported urban-rural difference across time period, however, the evaluation on urban-rural differences in age and birth cohort effects is limited. Our aim was to quantitatively assess urban-rural disparities in age, period and cohort effects in breast cancer mortality in China. Methods: We collected age-specific breast cancer mortality rates for urban and rural females aged 20-84 years from 1987 to 2021. Hierarchical age-period-cohort (HAPC) models were used to evaluate the effect of area (urban, rural) on breast cancer mortality and investigate urban-rural differences in age, time period and birth cohort effects. Results: We found a significant area (urban, rural) effect on breast cancer mortality in that rural females had a lower mortality risk than urban females [-0.25 (95 % confidence interval (CI):-0.32,-0.17)]. Age trajectories of mortality based on the HAPC model showed nonlinear trends with adjustment for area variable. The urban-rural difference in age effect appeared to be divergent with age, and urban women had higher mortality risk in the senior age group. The urban-rural difference in birth cohort effect indicated a reversal around the birth cohort group of 1962-1966, after which rural females had a higher mortality risk than urban females. Conclusion: The area (urban, rural) could affect breast cancer mortality among women, and the effect of urban-rural difference varies with age and birth cohort. To promote the health of urban and rural females, the gap between urban and rural areas should be shorten.