LUMPECTOMY AND RADIATION-THERAPY FOR THE TREATMENT OF INTRADUCTAL BREAST-CANCER - FINDINGS FROM NATIONAL SURGICAL ADJUVANT BREAST AND BOWELPROJECT B-17

Purpose: In 1993, findings from a National Surgical Adjuvant Breast an d Bowel Project (NSABP) trial to evaluate the worth of radiation thera py after lumpectomy concluded that the combination was more beneficial than lumpectomy alone for localized intraductal carcinoma-in-situ (DC IS). This report extends those findings. Patients and Methods: Women ( N = 818) with localized DCIS were randomly assigned to lumpectomy or l umpectomy plus radiation (50 Gy). Tissue was removed so that resected specimen margins were histologically tumor-free. Mean follow-up time w as 90 months (range, 67 to 130). Size and method of tumor detection we re determined by central clinical, mammographic, and pathologic assess ment. Life-table estimates of event-free survival and survival, averag e annual rates of occurrence for specific events, relative risks for e vent-specific end points, and cumulative probability of specific event s comprising event-free survival are presented. Results: The benefit o f lumpectomy plus radiation was virtually unchanged between 5 and 8 ye ars of follow-up and was due to a reduction in invasive and noninvasiv e ipsilateral breast tumors (IBTs). Incidence of locoregional and dist ant events remained similar in both treatment groups; deaths were only infrequently related to breast cancer. Incidence of noninvasive IBT w as reduced from 13.4% to 8.2% (P = .007), and of invasive IBT, from 13 .4% to 3.9% (P < .0001). All cohorts benefited from radiation regardle ss of clinical or mammographic tumor characteristics. Conclusion: Thro ugh 8 years of follow-up, our findings continue to indicate that lumpe ctomy plus radiation is more beneficial than lumpectomy alone for wome n with localized, mammographically detected DCIS. When evaluated accor ding to the mammographic characteristics of their DCIS, all groups ben efited from radiation. (C) 1998 by American Society of Clinical Oncolo gy.