Pathologic findings from the National Surgical Adjuvant Breast Project(NSABP) Protocol B-17: Intraductal carcinoma (ductal carcinoma in situ).

BACKGROUND. Controversy exists concerning the natural history of ductal carcinoma in situ (DCIS) of the breast, including its pathologicexpression and treatment. This controversy has been fostered largely bythe retrospective nature and limited sample sizes of extant studies. 

METHOD. Resolution of some of these issues was attempted by analyzing the pathologicfeatures of 573 examples of DCIS obtained from a larger cohort of 790 womenwith DCIS enrolled in Protocol B-17 of the National Surgical Adjuvant Breast Project. This prospective randomized clinical trial was performed to assess the efficacy of local breast irradiation to reduce the incidence of secondipsilateral breast tumors (IBT) after lumpectomy. 

RESULTS. Tumor and patient characteristics, including significantlyless IBT for those treated by lumpectomy and irradiation than lumpectomy alone, were almost identical for the subset comprising this analysis andthe total B-17 cohort reported previously. The presence of moderate/marked comedo necrosis, which was evaluated as an independent parameter ratherthan as a specific histologic type of DCIS and uncertain/involved lumpectomymargins were the only statistically significant independent predictorsof IBT for patients treated by lumpectomy as well as irradiation. The latter markedly reduced the annual hazard rates for the IBT associated with theseindicators. 

CONCLUSIONS. Although not an endpoint of this study, the authors' findings suggest that the beneficial effect of irradiation in reducing IBT after lumpectomy for DCIS occurs with small (< 1.0 cm.) and larger lesions. Moderate/marked comedo necrosis and uncertain/involved lumpectomy margins represent independent predictors of IBT. 
 
National Surgical Adjuvant Breast and Bowel Project Headquarters, Shadyside Hospital, Pittsburgh, PA 15232. 
Medline ID: 95188112