Pathologic findings from the National Surgical Adjuvant Breast Project (NSABP) eight-year update of Protocol B-17 - Intraductal carcinoma

BACKGROUND. This report is an 8-year update of the authors' previous findin gs from National Surgical Adjuvant Breast Project (NSABP) Protocol B-17, wh ich relates to the influence of pathologic characteristics on the natural h istory and treatment of intraductal carcinoma (DCIS). METHODS. Nine pathologic features observed in a pathologic subset of 623 of 814 evaluable women enrolled in this randomized clinical trial were assess ed for their role in the prediction of second ipsilateral breast tumors (IB T), other events, and selection of breast irradiation (XRT) following lumpe ctomy. RESULTS. The frequency of subsequent IBT was reduced from 31% to 13% (P = 0 .0001) by XRT. The average annual hazard rates for IBT were reduced by XRT for all pathologic features examined. Four characteristics were individuall y noted to be significantly related to IBT, but only moderate-to-marked and absent-to-slight comedo necrosis were found to be independent high and low risk predictors, respectively, for such an event in patients of both treat ment groups. XRT effected a 7% absolute reduction at. 8 years in the low ri sk group. Despite a relatively high incidence (approximate to 40%) of BET c onsisting of invasive cancer, mortality due to breast carcinoma after DCIS for the entire cohort was found to be only 1.6% at 8 years. CONCLUSIONS. The degree of comedo necrosis in patients with DCIS appears to be sufficient for discriminating between high and low risks for IBT follow ing lumpectomy for DCIS. Although margin status, unlike in our previous rep ort, was found to have only a slight or borderline influence on the frequen cy of IBT at 8 years, excision of DCIS with free margins is advised. The lo w risk group exhibits a statistically significant reduction of IBT from XRT . The decision to forgo XRT in the treatment of this singular subset of pat ients would appear to depend on clinical considerations and the input of in formed patients rather than being standard practice. (C) 1999 American Canc er Society.