Use of postexcision preirradiation mammography in patients with ductal carcinoma in situ of the breast treated with breast-conserving therapy.

PURPOSE: Postexcision preirradiation mammography (PPM) is frequently performed in patients with ductal carcinoma in situ (DCIS) treated with breast-conserving therapy (BCT) to evaluate for residual suspicious calcifications; but no clear evidence supports this practice. The current study was undertaken to investigate the value of PPM in the management of patients with DCIS. METHODS AND MATERIALS: We conducted a retrospective review of patients treated for DCIS with BCT at the University of Pennsylvania. The impact of PPM on surgical management and on local recurrence was evaluated. Factors associated with the use of PPM, the results of PPM, and the likelihood of finding residual malignancy at the time of re-excision in patients with PPM were also examined. RESULTS: One hundred forty-four of 281 patients (51%) underwent PPM. Of the 144 patients who received PPM, 34 (24%; 95% confidence interval, 17%-31%) had residual suspicious calcifications (a positive PPM ). Of the 34 patients with a positive PPM, all underwent a re-excision and 19 (56%; 95% confidence interval, 35%-70%) were found to have residual malignancy. Ten of 34 patients with a positive PPM had negative margins, of which 6 had a residual malignancy. Assuming all patients with close, positive, or indeterminate surgical margins would have undergone re-excision regardless of the findings of PPM, PPM resulted in a change in surgical management in 7% (10/144) of patients and removal of residual DCIS in 4% (6/144). With a median follow-up of 9.5 years, the use of PPM was not associated with an improvement in 10-year local recurrence-free survival (94.8% vs 91.5%, P = .368). CONCLUSIONS: In this study, PPM affected surgical management in only a small percentage of patients and had no impact on local recurrence. The routine use of PPM in women undergoing BCT for DCIS may not be warranted