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Sep 6, 2016 09:40PM
Oct 26, 2016 04:33PM
Thanks Annette47. I would be concerned that it might not be appropriate to extrapolate from different settings with potentially different risk profiles.
I note that the featured document in the link you posted is a guideline pertaining to margins for breast-conserving surgery ("lumpectomy") with whole-breast irradiation in stages I and II invasive breast cancer.
SSO / ASTRO (2014): Society of Surgical Oncology American Society for Radiation Oncology Consensus Guideline on Margins for Breast-Conserving Surgery With Whole-Breast Irradiation in Stages I and II Invasive Breast Cancer
ASCO endorsed this guideline with some qualifications here:
ASCO (2014): Margins for Breast-Conserving Surgery With Whole-Breast Irradiation in Stage I and II Invasive Breast Cancer: American Society of Clinical Oncology Endorsement of the Society of Surgical Oncology/American Society for Radiation Oncology Consensus Guideline
Denise-G recently posted a link to a guideline pertinent to margin sizes for those receiving breast-conserving surgery ("lumpectomy") and whole breast irradiation ("WBRT") for DCIS:
ASCO (2016): http://jco.ascopubs.org/content/early/2016/08/10/JCO.2016.68.3573.full
(A pdf version is available there also)
[EDIT 10/26/2016: A PDF version was also published here: http://www.practicalradonc.org/article/S1879-8500(16)30109-6/pdf ]
"There are limitations to this guideline. It applies to patients with DCIS and DCIS-M treated with WBRT. The findings should not be extrapolated to DCIS patients treated with APBI or those with invasive carcinoma for whom a separate guideline has been developed.(33) While studies including patients treated with and without WBRT were included in the meta-analysis, a meta-analysis of studies of treatment with excision alone was not conducted. Additionally, all of the studies included in the meta-analysis were retrospective. However, in the absence of any planned prospective randomized trials addressing the question of margin width and local recurrence, these studies represent the best available evidence for clinical decision making."
Thus, with breast conserving therapy ("BCT"), those with DCIS should look to the BCT / DCIS guideline, while those with invasive disease should in general look to the BCT / invasive guidelines. There is overlap between the DCIS Margin Guideline and the Invasive Cancer Margin Guideline for DCIS with micro-invasion (DCIS-M or DCIS-MI), a point to discuss with one's Radiation Oncologist perhaps.
NCCN guidelines (Version 2.2016) include a completely separate algorithm for post-mastectomy radiation in the setting of invasive disease (Stage I, IIA, or IIB disease OR T3, N1, M0), which takes into account nodal status, tumor size, and margin status. [EDIT (Sept 19, 2016): See also, this recent ASCO–ASTRO–SSO guideline update regarding post-mastectomy radiotherapy in invasive T1-T2 size tumors:
ASCO–ASTRO–SSO (2016): http://jco.ascopubs.org/content/early/2016/09/15/JCO.2016.69.1188.full#ref-3
ASCO–ASTRO–SSO(2016): PDF version
[EDIT 10/26/2016): A PDF version is also available here (upper right): http://link.springer.com/article/10.1245/s10434-016-5558-8 ]
T1 Tumor ≤ 20 mm in greatest dimension;
T2 Tumor > 20 mm but ≤ 50 mm in greatest dimension. ]
For DCIS with mastectomy, the adequacy of margins is based on different studies done in a different patient population. The clinical studies of the adequacy of margins in patients with DCIS treated by mastectomy do not appear to be entirely consistent, including recent publications in 2015 and 2013. Thus, if there is a question about the adequacy of mastectomy margins and whether post-mastectomy radiation should be considered or not, consultation with a Radiation Oncologist is the probably the best approach to ensure receipt of up-to-date, accurate, case-specific advice, based on expert interpretation of the relevant clinical studies in the DCIS mastectomy setting.
Stage IA IDC, 9/2013 BMX. Right: IDC (1.5 mm, grade 2) with DCIS (5+ cm), 0/4 nodes, pN0. Left: DCIS (5+ cm), 0/1 node, pN0(i+).