Margin width as the sole determinant of local recurrence after breast conservation in patients with ductal carcinoma in situ of the breast.

BACKGROUND: A previous study showed a 3% local recurrence risk at 8 years in ductal carcinoma in situ (DCIS) patients treated with excision alone with surgical margins of 10 mm or greater. This study updates those data.
METHODS: A total of 272 DCIS patients treated conservatively with 10 mm or greater margins were reviewed in a prospective database.
RESULTS: Among 212 excision-alone patients, there were 9 DCIS and 3 invasive recurrences. The 12-year probability of any local recurrence was 13.9%; of invasive recurrence it was 3.4%. Among 60 excision plus radiation patients, there was 1 local (invasive) recurrence (P = .06). The 12-year probability of local recurrence was 2.5%.
CONCLUSIONS: Local recurrence in DCIS patients treated with excision alone with margins of 10 mm or greater compares favorably with local recurrence in DCIS patients with nontransected margins and treated with postoperative radiation. The risk of invasive recurrence among widely excised DCIS patients is extremely low.