Radiation therapy as an adjunct to primary surgery in early stage breast cancer: biological and clinical rationale.

Abstract

In spite of the widespread use of adjuvant endocrine and cytotoxic chemotherapy, a substantial proportion of patients with early-stage breast cancer eventually develop a distant disease recurrence. Local control also remains a clinically significant problem in subsets of patients. Whether improved local control through the use of postoperative radiation therapy would prevent distant dissemination has been much debated for several decades. Studies on the long-term outcome of systemically untreated breast cancer patients indicate that breast cancer in many patients is a local disease that can be cured by surgery or radiotherapy. Randomized trials of breast screening have also shown that a delay in effective local treatment is associated with an increased incidence of distant dissemination and death from to the disease. Data from individual randomized trials and overviews of postoperative radiation therapy have indicated that radiation therapy as an adjunct to primary surgery is associated with a decrease in distant dissemination and breast cancer death. This benefit may be translated into a substantial overall survival benefit, provided that the treatment technique avoids long-term cardiac side effects. In many of the older radiation therapy trials, such effects appear to have balanced the benefit in terms of a reduced incidence of distant disease among the patients allocated to radiotherapy.