Comparing long-term local recurrence rates of surgical and non-surgical management of close anterior margins in breast conserving surgery

While it is known that histologically involved margins lead to a higher local recurrence rate, re-excision of anterior margins is less common than that of radial margins. However, there are minimal long-term data on the oncological safety of non-surgical management of anterior margins. A retrospective study was performed of all patients who underwent breast conserving surgery for breast cancer between 2000 and 2008 at two tertiary referral centres. A close margin was defined as disease within two mm of the resection margin (including disease at the margin). 6922 patients underwent surgery for invasive or in situ breast cancer of whom 277 patients had a close anterior margin alone after breast conserving surgery. Two hundred and twenty patients had non-surgical management of their margins, while 57 had re-excision surgery. Overall, there were 4/57 local recurrences in the surgical management group and 12/220 in the non-surgical management group. The local recurrence-free survival rate at 5 years was 98.2% (1 recurrence, 95% CI 87.8–99.7) in the surgical management group and 97.2% (6 recurrences, 95% CI 93.8–98.7) in the non-surgical management group. At 10 years, the rates were 92.2% (4 recurrences, 95% CI 80.3–97.0) in the surgical management group and 93.9% (12 recurrences, 95% CI 89.4–96.5) in the non-surgical management group. There was no significant difference found in the local recurrence rate between management groups (HR 1.24, 95% CI 0.40, 3.85; p = 0.71). Local recurrence rates are acceptable and similar in both the surgically and non-surgically managed groups. Non-surgical management of close anterior margins appears oncologically safe when combined with appropriate adjuvant therapy.