Abstract P1-10-16: Standardization of nodal radiation therapy (RT) through changes to a breast cancer clinical pathway (CP) in a large, integrated comprehensive cancer center network
Authors: Gebhardt BJ , Horne ZD , Heron DE , Beriwal S 
Published: March 2017

Abstract
Purpose
The efficacy of adjuvant RT following breast conserving surgery (BCS) in reducing risk of local recurrence is established. The results of Z11, AMAROS and MA-20 studies led to wide variation in RT treatment volume for patients (pts) who have sentinel node biopsy positive disease. CP's are a mechanism of standardizing care when many therapeutic options exist and clinical practice varies unnecessarily. We sought to evaluate the impact of changes to a CP guiding adjuvant RT in sentinel node positive pts for invasive breast cancer (IBC) on practice patterns throughout a large cancer network.
Methods
In 2003, we implemented a CP for management of IBC with adjuvant RT. In 2009, we required entry of management decisions into an online tool integrated with medical records to track CP choices and subject off-pathway selections to peer-review. The CP for treatment of pts with positive sentinel lymph nodes (LN) following BCS was modified in February 2015 to promote uniform treatment of regional LN irradiation (RNI). In summary, the CP recommended modified tangents (MT) including level 1 and 2 nodes for all pts with micrometastases. For pts with macrometastases, CP recommended including level 1 and 2 LN in MT and add additional field to include level 3, supraclavicular LN +/- IM node for pts with any adverse factor present defined as T2 disease, LVSI, high grade, ER negative, ECE or premenopausal pts. Data from treatment decisions entered into the support tool from June 2009 to April 2016 were obtained.
Results
From 2009 until CP modification in 2015, 1089 treatment decisions were entered. Decisions were heterogeneous and included 24 distinct options. Following pathway amendment, 178 decisions were entered. Three pts were enrolled in clinical trials & 9 referred to other providers and excluded. Of the remaining 166 pts, 7 (4.2%) were treated off pathway for poor performance status, patient preference, or gross residual disease. The 159 (95.8%) on-pathway pts were analyzed. Median age was 61 (range 32-90) years. All pts underwent BCS for IBC and had positive sentinel LN. Forty-four (27.7%) pts had micrometastastatic LN disease, and 115 (72.3%) had macrometastases, of which 82 (71.3%) had adverse risk factors. All 44 pts with micrometastases were treated with MT. Six (5.2%) pts with macrometastases were treated with WBT RT, 33 (28.7%) with MT, & 76 (66.1%) with MT and a 3rd field. Seventy-six (92.7%) pts with adverse risk factors were treated with MT and 3rd field (p&lt;0.001).
Conclusions
CP's are useful tools for translating published research, national guidelines, and institutional experience into standardized patient management plans to promote evidence-based care and eliminate unnecessary variations in practice patterns that lead to inefficiency and inferior outcomes. Recognizing that our CP for adjuvant treatment of patients with positive sentinel LNs undergoing BCS allowed heterogeneous treatment selections, we modified the CP in 2015 based upon the latest evidence regarding RNI. We found that following the amendment, patients received RT fields guided by the CP leading to more standardized treatment based upon clinical risk factors and facilitating tracking of patient outcomes.
Citation Format: Gebhardt BJ, Horne ZD, Heron DE, Beriwal S. Standardization of nodal radiation therapy (RT) through changes to a breast cancer clinical pathway (CP) in a large, integrated comprehensive cancer center network [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-10-16.