Radiotherapeutic considerations in the treatment of primary breast cancer.

Abstract

Patients who are candidates for conservative surgery and radiation include those with a primary tumor size of less than 4-5 cm, without evidence of gross multicentricity or diffuse microcalcifications. Patients with an extensive intraductal component may be appropriate candidates, provided that margins of resection are negative. Focally positive margins of resection in patients without an extensive intraductal component are not a contraindication, provided that a boost dose of radiation is employed; young age is also not a contraindication to conservative treatment. The optimal radiotherapy technique includes a total dose to the breast of 4500-5000 cGy with a daily fraction size of less than 250 cGy and a weekly dose of more than 800 cGy. The role of boost treatment in patients with negative margins of resection is currently under investigation. Boost treatment is essential in patients with positive margins. A direct photon-beam field to treat the internal mammary nodes should be avoided, especially in patients receiving chemotherapy. The subset of patients for whom the addition of radiation following an excisional biopsy does not result in a decreased risk of breast cancer recurrence remains to be defined and is currently being evaluated in several prospective randomized trials. The optimal sequencing of adjuvant chemotherapy and primary radiotherapy has not been determined.