NCCN VERSION 2 2015

The NCCN Guidelines® and this illustration may not be reproduced in any form without the express written permission of NCCN®.

MS-8

NCCN Guidelines Index

Breast Cancer Table of Contents

Discussion

NCCN Guidelines Version 2.2015

Breast Cancer

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.

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.

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.

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.

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.

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.

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.

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,

< .0000).

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.