The role of reexcision for positive margins in optimizing local disease control after breast-conserving surgery for cancer.

One of the most important factors associated with local recurrence after lumpectomy in breast cancer patients is the status of the surgical margin. Standard surgical practice is to obtain clear margins even if this requires a second surgical procedure. It is assumed that reexcision to achieve clear margins when positive margins are present at initial excision is as effective as complete tumor removal at a single procedure; however, the efficacy of reexcision in this context has not been well studied. A retrospective search of the Henrietta Banting Breast Centre database from 1987 to 1997 identified 1430 patients who underwent lumpectomy for invasive breast cancer: 1225 patients (group A) had negative margins at the initial surgery and 152 patients (group B) underwent one or more reexcisions to achieve negative margins. Fifty-three patients had positive margins at final surgery, but no reexcision was done (group C). Logistic regression was used to identify factors that were predictive of a positive margin; predictors of local recurrence in women whose tumors were completely resected were determined using Cox's proportional hazards model. Patients in groups A, B, and C differed with respect to mean age at diagnosis (58 years, 51 versus, and 56 years, respectively, p < 0.0001), mean tumor size (19 mm, 16 mm, and 26 mm, respectively, p < 0.0001), node positivity (30%, 22%, and 41%, respectively, p = 0.004), and the presence of a ductal carcinoma in situ (DCIS) component (60%, 64%, and 79%, respectively, p = 0.007). The mean follow-up period was similar for the three groups (8 years, 8 years, and 9 years, respectively, p = 0.17). Young age was the only variable predictive of positive margins. Among patients undergoing complete tumor excision, there was a suggestion of a higher 10 year local recurrence rate in reexcision group B, but the difference did not reach statistical significance (11.6% versus 16.6%, p = 0.11). Cox's multivariate regression analyses identified older age, smaller tumor size, receiving radiation therapy, and tamoxifen use as significantly decreasing the rate of local recurrence in patients with negative margins at initial surgery or after reexcision. Our data confirm the results of previous studies indicating that young age is an independent predictor of positive margins after lumpectomy for invasive breast cancer. The only independent predictor of local recurrence in our study cohort was large tumor size. There was a trend toward a higher local recurrence rate if more than one procedure was required to secure clear margins, although this effect was not independent of other factors. Reexcision to clear involved margins is an important surgical intervention for both younger and older women.