Extent, distribution, and mammographic/histological correlations of breast ductal carcinoma in situ.

To assess the potential of breast-conserving treatment for ductal carcinoma in situ (DCIS), 82 mastectomy specimens were studied by Egan's serial subgross method. 42 (51%) of the tumours were larger than 50 mm and only 12 (15%) were smaller than 20 mm; the size distribution was not affected by the mode of detection (mammography 52 cases, clinical examination 30). All but 1 case showed only 1 region of tumour. 66% of tumours involved one breast quadrant, 23% extended over more than one quadrant, and 11% were centrally located. Mammographic estimates, based on the extent of microcalcifications, frequently underestimated the histological size of tumours, the extent of the discrepancy being related to the histological type--8/50 predominantly micropapillary/cribriform. In view of the frequently large size, adequate excision of many DCIS will require a wide excision involving up to a whole quadrant.