Second malignancies after treatment of early-stage breast cancer: Lumpectomy and radiation therapy versus mastectomy

Purpose: To determine the risk of second malignancies after lumpectomy and radiation therapy (LRT), and to compare it with that in a similar cohort of early-stage breast cancer patients undergoing mastectomy without radiation (MAST). Patients and Methods: Between January 1970 and December 1990, 1,029 breast cancer patients at our institution underwent LRT. A cohort of 1,387 breast cancer patients who underwent surgical treatment by mastectomy (MAST), and who did not receive postoperative radiation during the same rime period, se rved as a comparison group. Second malignancies were categorized as contral ateral breast versus nonbreast. In the cohort of patients undergoing LRT, a detailed analysis was carried out with respect to age, disease stage, smok ing history, radiation therapy technique, dose, the use of chemotherapy ar hormone therapy and other clinical and/or pathologic characteristics. Results: As of March 1999, the median follow-up was 14.6 years for the LRT group and 16 years for the MAST group. The 15-year risk of any second malig nancy was nearly identical for both cohorts (17.5% v 19%, respectively). Th e second breast malignancy rate at 15 years was 10% for both the MAST and L RT groups. The 15-year risk of a second nonbreast malignancy wets 11% for t he LRT and 10% for the MAST group. In the subset of patients 45 years of ag e or younger at the time of treatment, the second breast and nonbreast mali gnancy rates at 15 years were 10% and 5% for patients undergoing LRT versus 7% and 4% for patients undergoing mastectomy (P, not statistically signifi cant). In the detailed analysis of LRT patients, second lung malignancies w ere associated with a history of tobacco use. There were fewer contralatera l breast rumors in patients undergoing adjuvant hormone therapy, although t his did not reach statistical significance. The adjuvant use of chemotherap y did nat significantly affect the risk of second malignancies. Conclusion: There seems to be no increased risk of second malignancies in p atients undergoing LRT using modern techniques, compared with MAST. Continu ed monitoring of these patient cohorts will be required in order to documen t that these findings are maintained with even longer follow-up periods. Wi th nearly 15 years median follow-vp periods, however, these data should be reassuring to women who are considering LRT as a treatment option. J Clin O ncol 18:2406-2412. (C) 2000 by American Society of Clinical Oncology.