Histopathological study of local residual carcinoma after simulated lumpectomy.

From 1989 to 1991, 24 patients with invasive ductal carcinoma underwent simulated lumpectomy at Tokyo Women's Medical College Daini Hospital. The mastectomy specimens were then examined histopathologically in serial sections for the presence of residual tumors or multicentricity. Lumpectomy specimens from cancer foci at resected margins were also examined. In this study, 23 of 24 patients demonstrated positive resection margins (95.8%). Residual tumors were found in mastectomy specimens from 16 patients (66.7%); unilateral multifocal carcinomas were found in 2 of these patients (8.3%). The incidence and severity of residual tumors did not correlate with primary tumor size or the distance between the nipple and the primary tumor but directly correlated with the severity of intraductal spread of the primary tumor. Tumors with central necrosis were associated with a higher incidence of residual tumors. Our study thus indicates that there is a high risk that some residual tumor will be left in the conserved breast when lumpectomy is performed. Multifocal carcinoma and tumors showing severe intraductal spread and central necrosis are thus associated with extensive residual tumors and are likely to cause local recurrence.