Geography of breast cancer incidence according to age & birth cohorts

- Breast cancer incidence varies spatially by age and birth cohorts, as well as by time period.
- We found the global distribution of incidence rates across places to be more heterogeneous for younger women and later birth cohorts.
- Geographic variation by age groups was more pronounced than by birth cohorts.
- The research augments what is known about period effects on breast cancer's geography with findings specific to disease incidence throughout the life course (age effects) and across life experiences (birth effects).

PurposeGeographic variation in breast cancer incidence across Connecticut was examined according to age and birth cohort -specific groups.MethodsWe assigned each of 60,937 incident breast cancer cases diagnosed in Connecticut, 1986-2009, to one of 828 census tracts around the state. Global and local spatial statistics estimated rate variation across the state according to age and birth cohorts.ResultsWe found the global distribution of incidence rates across places to be more heterogeneous for younger women and later birth cohorts. Concurrently, the spatial scan identified more locations with significantly high rates that pertained to larger proportions of at-risk women within these groups. Geographic variation by age groups was more pronounced than by birth cohorts.ConclusionGeographic patterns of cancer incidence exhibit differences within and across age and birth cohorts. With the continued insights from descriptive epidemiology, our capacity to effectively limit spatial disparities in cancer will improve.