Cancer in the Contralateral Breast after Radiotherapy for Breast Cancer

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Abstract
In the March 19 issue, Boice et al.1 present data to indicate that radiotherapy for breast cancer contributes little to the already high risk of a second cancer in the opposite breast. They note, however, that the risk was significantly increased among women who underwent irradiation at a relatively young age (2 and may reflect technical factors such as the orientation of the anterior internal mammary field and the use of orthovoltage or cobalt-treatment machines. With current techniques, such as those used in randomized trials comparing conservative surgery and radiation therapy with mastectomy in early-stage disease, a higher incidence of cancer in the contralateral breast has not been identified among patients who undergo irradiation.3 4 5 Nonetheless, since the risk of carcinogenesis may increase with the dose of radiation absorbed by the contralateral breast, we think it worthwhile to emphasize that techniques have been described by Fraass et al.2 that can further reduce the dose to approximately 0.50 Gy. Their recommendations include avoiding half-blocking on tangential fields, angling tangential fields to make the deep edges coplanar, using wedges when necessary only in the lateral tangential field, and limiting the collimator opening during port films.