Background: Breast conserving surgery (BCS) is common practice for unifocal ductal carcinoma in situ (DCIS) less than 4 cm in size, but the extent of tumor free margin width around DCIS necessary to minimize recurrence is unclear.
Methods: Clinical and pathologic details were recorded from all patients with pure DCIS < 4 cm in size, treated with BCS between 1978 and 1997. Histologic margins were measured by using an ocular micrometer. Patients with clear margins (> 1 mm) were divided up into 3 groups for analysis based on margin of normal tissue excised: 1.1-5 mm, 5.1-10 mm, and 10.1-40 mm.
Results: There were 66 patients with close margins (< or = 1 mm), of which 25 cases (37.9%) recurred. The recurrence rates for the 3 clear margin groups ranged from 4.5-7.1%. Median followup was 47 months (range 12-197 mos). Risk of recurrence in the group with close margins was greater than the subgroups with clear margins (P < 0.001); no differences in recurrence was seen between the individual subgroups with clear margins. Nuclear Grade 3 was predictive of recurrence (P = 0.03). Following excision alone, the recurrence rate was 18.6%, compared with 11.1% when radiotherapy was given as adjuvant therapy. Women with clear margins following excision had a recurrence rate of only 8.1%.
Conclusion: After BCS for DCIS, close margins were associated with a high risk of local recurrence. Radiotherapy did not compensate for inadequate surgical clearance.
Copyright 2001 American Cancer Society.