Cardiac mortality and morbidity after breast cancer treatment.

BACKGROUND Breast conservation treatment for early-stage breast cancer has been demonstrated to be equivalent to mastectomy in a large number of randomized trials. A number of earlier studies of surgery with or without radiation did not show an improvement in overall survival despite large reductions in local recurrence rates. Numerous randomized trials have demonstrated that postmastectomy radiation to the chest wall and regional nodes in high-risk early-stage patients provides improvements in local-regional control and overall survival. METHODS This article reviews the medical literature pertaining to long-term cardiac toxicity in early-stage breast cancer patients treated with either breast conservation or postmastectomy radiation. RESULTS A decrease in breast cancer deaths associated with postoperative irradiation was offset by an increase in cardiovascular deaths in early studies. Cardiac toxicity of breast irradiation is a late event, manifesting clinically 10 or more years after breast cancer treatment. The excess deaths were directly related to radiation techniques that exposed excessive volumes of the heart, leading to the development of new techniques designed to shield the heart and reduce the risk of cardiac toxicity. CONCLUSIONS This review examines the original and contemporary studies of radiation for postmastectomy and breast conservation treatment for early-stage breast cancer, discusses the long-term cardiac mortality and morbidity data from these studies, and reviews the known risk factors associated with cardiac toxicity after irradiation for breast cancer.