BACKGROUND: The risk of female breast cancer in association with radiation dose is well established, on the basis of follow-up studies of the atomic bomb survivors and other exposed populations. This association is especially strong for women exposed before 20 years of age and appears to be much weaker among women exposed after 40 years of age. METHODS: Breast tissue samples from 88 high-dose and 225 low-dose autopsy cases from the Radiation Effects Research Foundation Life Span Study sample were examined in detail to determine whether nonproliferative and proliferative breast lesions are associated with radiation dose. RESULTS: Prevalence of proliferative disease in general and atypical hyperplasia in particular were positively associated with radiation dose. The associations were strongest for subjects who were between 40 and 49 years of age at the time of the bombing. CONCLUSIONS: It is hypothesized that the strongest association in women 40 to 49 years of age may be related to the age dependence of radiation-induced breast cancer, in that potential cancers induced in this age group by radiation exposure may receive too little hormonal promotion to progress to frank cancers.
BACKGROUND: The risk of female breast cancer in association with radiation dose is well established, on the basis of follow-up studies of the atomic bomb survivors and other exposed populations. This association is especially strong for women exposed before 20 years of age and appears to be much weaker among women exposed after 40 years of age. METHODS: Breast tissue samples from 88 high-dose and 225 low-dose autopsy cases from the Radiation Effects Research Foundation Life Span Study sample were examined in detail to determine whether nonproliferative and proliferative breast lesions are associated with radiation dose. RESULTS: Prevalence of proliferative disease in general and atypical hyperplasia in particular were positively associated with radiation dose. The associations were strongest for subjects who were between 40 and 49 years of age at the time of the bombing. CONCLUSIONS: It is hypothesized that the strongest association in women 40 to 49 years of age may be related to the age dependence of radiation-induced breast cancer, in that potential cancers induced in this age group by radiation exposure may receive too little hormonal promotion to progress to frank cancers.