Intrinsic Subtypes of Breast Cancer among Atomic-bomb Survivors (Addendum to RP 5-08)

Summary

‘Intrinsic’ subtypes of breast cancer defined by gene expression profiling studies are thought to be associated with pathogenesis and prognosis (biological properties) of breast cancer, and seem to be related to some etiologic factors. This molecular classification can be approximated by immunohistochemical (IHC) staining of key markers. As part of the special cancer incidence study (RERF RP 5-08: Breast cancer incidence among atomic-bomb survivors, 1950-2005), we propose to investigate the intrinsic subtypes of breast cancer cases to add new insights into biological properties of breast cancer in relation to atomic-bomb radiation exposure. Collaborating with pathologists and hospitals in Hiroshima and Nagasaki, we will collect paraffin-embedded tissues of breast cancers that occurred in the members of the Life Span Study (LSS) population, and perform IHC staining of targeted receptor markers to study associations of specific subtypes and radiation exposure with consideration of patient’s age and calendar year at diagnosis, birth cohort of the subjects, age at exposure to radiation, and also anthropometric indices, reproductive histories, and other individual factors. The results will provide insights into biological mechanisms of radiation-induced breast carcinogenesis and provide important information for future molecular studies of radiation-related subgroups to elucidate possible molecular changes associated with radiation-induced breast cancer.

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