Existing management of ductal carcinoma in situ of the breast is surgical removal of the tumor by lumpectomy or by modified radical mastectomy. Microscopic examination during and after the procedure defines the surgical margin as negative if there are no visible tumor cells or positive if there are tumor cells.

Currently, the combination of re-excision for positive margins and radiation therapy is standard management of ductal carcinoma in situ. Recent studies have shown that wide local excision (namely, lumpectomy) alone without radiation therapy may be appropriate for some patients; studies have tried to stratify these patients according to multiple prognostic factors such as patient age, tumor grade, tumor size, margin width, and specimen processing.

In the current, retrospective study, Dr. Neuschatz and colleagues examined clinical and pathological characteristics of ductal carcinoma in situ treated with initial lumpectomy followed by subsequent re-excision to determine factors that significantly predict successful and complete removal of tumor from the breast.

They reviewed 253 cases of ductal carcinoma in situ treated from 1987 to 2000 with lumpectomy and re-excision. Prognostic factors evaluated included lesion or specimen size, margin width, margin status and degree of positivity, nuclear grade, presence of necrosis, patient age, and the extent of specimen processing. The amount of residual tumor was categorized as microscopic, small, medium or large. Univariate and multivariate analysis by logistic regression models were used to determine statistical significance of the various factors.

Initial excision margin width was the most significant factor for presence of residual tumor. None of the specimens with margin widths greater than 2 mm contained residual tumor, whereas 31% of margin widths between 1 and 2 mm and 41% of margin widths between 0 and 1 mm contained residual tumor.

As the degree of positive margin increased, the presence of residual tumor in the breast became more likely. About 85% of extensively positive margins and 68% of moderately positive margins contained residual tumor on re-excision (with 23% and 26% of specimens containing medium to large amounts of residual tumor, respectively). In contrast, 46% of minimally positive and 30% of focally positive margins contained residual tumor on re-excision (with 0 to 9% containing medium to large amounts of residual tumor).

Univariate and multivariate analyses showed that initial excision margin (P<0.0001) and initial tumor size (P=0.02) were both found to be significant predictors of finding tumor on re-excision and finding a medium-to-large residual tumor. Nuclear grade, age, specimen processing, and tumor necrosis were not significant predictors.

The authors conclude, "margin width on initial excision is the dominant factor in predicting the presence of residual tumor," and "more extensively positive margins are more likely to contain residual tumor on re-excision than those specimens with less extensively positive margins." The authors add, "this study should serve to help identify those women unlikely to have residual tumor in the breast who may not need further treatment, and those women likely to have a significant volume of residual tumor in the breast who may require further aggressive treatment."