NCCN VERSION 2 2015

NCCN Guidelines Version 2.2015 Breast Cancer

NCCN Guidelines Index Breast Cancer Table of Contents Discussion

and 82.9% of patients in the low-/intermediate-risk and high-risk arms, respectively, with margin widths of ≥10 mm or no tumor on re-excision observed in 48.5% and 53.3% of patients in the respective groups. 60 Although an acceptably low ipsilateral recurrence rate was observed in the low-/intermediate-grade arm of the study at 5 years, the 7-year ipsilateral recurrence rate in this group of patients was considerably higher (10.5%; 95% CI, 7.5%–13.6%), suggesting that these events may be delayed but not prevented in this population. Ipsilateral breast recurrences were approximately equally divided between invasive breast cancer and DCIS in the low-/intermediate-risk group but only about one-third of patients with an in-breast recurrence in the high-risk group had invasive disease. Prospective randomized trials have not been carried out to analyze whether wider margins can replace the need for radiation therapy for DCIS. A retrospective series demonstrated that for margin width of 10 mm, radiation had no additional benefit in reducing the already low local recurrence rate of 4% at the end of 8 years. 59 Also, if margin width was between 1 mm and <10 mm, the addition of radiation therapy led to a non-statistically significant reduction in local recurrence. However, when margins were <1 mm a significant benefit was seen. 59 Another retrospective study reviewed 220 patients with DCIS treated with breast conservation surgery and radiation. Thirty-six percent received a radiation boost. At 46 months, none of the 79 patients who received a radiation boost experienced a local recurrence, whereas 8 of 141 patients who did not receive a boost experienced a local recurrence. 61 Many factors impact on recurrence risk, including patient age, tumor size, tumor grade, and margin width. The definition of a negative margin has not been firmly established in DCIS. There appears to be a

consensus that margins >10 mm are adequate and margins <1 mm are inadequate, but no uniform consensus exists for margin status between these values. Results from a retrospective study of 445 patients with pure DCIS treated by excision alone indicated that margin width was the most important independent predictor of local recurrence, although the trend for decreasing local recurrence risk with increasing margin width was most apparent with margins <1 mm and ≥10 mm. 62 In a meta-analysis of 4660 patients with DCIS treated with breast-conserving surgery and radiation, a surgical margin of <2 mm was associated with increased rates of ipsilateral breast tumor recurrence (IBTR) compared with margins of 2 mm, although no significant differences were observed when margins of >2 mm to 5 mm or >5 mm were compared with 2-mm margins. 63 The results of this study suggest that wide margins (≥2 mm), which can compromise cosmetic outcome, do not provide additional benefit in the population of patients with DCIS receiving radiation therapy following breast-conserving therapy. A large, retrospective study found that narrow surgical resection margin (≤2 mm) does not increase local recurrence compared to a surgical resection margin of 2 mm. 64 Further complicating the issue of margin width is the impact of the fibroglandular boundary–the pectoral fascia and the superficial skin where narrower tumor-free margins may provide adequate local control. A meta-analyses of four large multicentre randomized trials confirmed the results of the individual trials that adding radiation therapy to breast conserving surgery for DCIS provides a statistically and clinical significant reduction in ipsilateral breast events (HR [hazard ratio],0.49; 95%CI; 0.41-0.58, P < .0000). 65 The choice of local treatment does not impact overall disease-related survival; therefore, the individual patient’s acceptance of the potential for an increased risk of local recurrence must be considered.

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