Purpose: Neither hormone-related nor genetics risk factors have been associated with the development of highly proliferative HER2-positive breast carcinomas. Because the majority of HER2-positive tumors present the amplification of the oncogene, we asked whether genomic instability triggered by irradiation might be involved in the induction of HER2-overexpressing breast carcinomas.
Experimental Design: Sixty-six infiltrating breast carcinomas from patients treated with radiation therapy for Hodgkin's lymphoma or other pediatric solid tumors and a control series of 61 consecutive sporadic breast tumors were analyzed by immunohistochemistry for HER2 expression with HercepTest.