Practical radiation oncology 2018
Standardization of nodal radiation therapy through changes to a breast cancer clinical pathway throughout a large, integrated cancer center network.
Abstract
Background
Studies demonstrate safety of omitting axillary nodal dissection for early-stage breast cancer with positive sentinel lymph node (+SLN) biopsy, although trial designs differed in radiation therapy (RT) fields. Regional nodal irradiation was separately shown to improve outcomes in high-risk patients. This led to lack of consensus in RT volumes. Clinical pathways (CPs) standardize care where practice varies unnecessarily. We evaluated the impact of changes to a CP guiding postoperative RT in women with +SLNs on practice patterns throughout a network.
Methods and materials
We implemented a CP for management of breast cancer with postoperative RT designed to promote uniform nodal treatment. The CP recommended modified tangents (MTs) including level I/II nodes for women with micrometastases (pN1mi). For women with macrometastases (pN1a), CPs recommended including level I/II LN in MT and a third supraclavicular node (SCN) LN ± internal mammary nodes for women with adverse factors present.
Results
RT fields of 233 women undergoing breast-conserving surgery with +SLN but not axillary nodal dissection were retrospectively reviewed: 25% had pN1mi disease and 75% pN1a. Of 127 women treated before CP changes, 35% with pN1mi and 22% with pN1a were treated with whole-breast irradiation alone. Following CP changes, 106 women were treated: 5% with whole-breast irradiation alone, 58% with MT, and 38% with MT + SCN field. Utilization of MT was associated with CP changes. Utilization of a third SCN field was associated with CP changes, pN stage, extracapsular extension, and total number of adverse factors.
Conclusions
CPs translate published data and institutional experience into management plans that promote evidence-based care and eliminate unnecessary practice variations. Recognizing that postoperative RT treatment volumes were heterogeneous, we modified the CP based upon the latest evidence for regional nodal irradiation, after which we found increased compliance and consistency with quality guidelines, which will also aid in tracking outcomes in future investigations.
Related Questions
Do you recommend axillary dissection for women with ER+ breast cancer and low risk Oncotype or Mammaprint if single node positive with only 1-2 SLN removed, to ensure <4 nodes positive?
No, I see no need to do dissection in this setting. Unless there is clinical or imaging evidence of gross disease, radiation should adequately control microscopic residual disease in the axilla.
How do you decide between high tangents or regional nodal radiation in patients with small, ER+ breast cancers who have a single positive sentinel node?
I tend to look at factors such as age, LVSI as well as number of SLN (1/1 vs. 1/2,3,4). After lumpectomy, for cases like this, my bias is to offer whole breast and RNI. I have also started offering more 40/15 to breast and lymph nodes so this approach doesn't lengthen course of treatment as compared...
If treating a patient with prior breast augmentation with whole breast radiation, would you alter your field setup?
With prior breast augmentation, I think you have a few options. Whole breast irradiation with tangents - I typically cover the entire chest wall and don't move the field edge forward. With respiratory motion (unless using DIBH or other respiratory techniques), I do worry about missing areas at risk...