SUMMARY: Breast cancer is the most common cancer among women in the US and about 1 in 8 women (12%) will develop invasive breast cancer during their lifetime. Approximately, 246,660 new cases of invasive breast cancer will be diagnosed in 2016 and 40,450 women will die of the disease. The update of the American Society of Clinical Oncology guideline concerning use of PostMastectomy RadioTherapy (PMRT) published in 2001, was developed by an expert panel following review of relevant literature published between January 2001 and July 2015 and further included a meta-analysis of 22 clinical trials published in 2014. Even though the use of PMRT has been widely accepted for patients with four or more positive lymph nodes, the role of PMRT for those with one to three positive nodes still remains controversial. This update addresses the issues at large and provides guidelines to help Health Care Providers and patients make informed decisions.
Clinical Question 1
Is PMRT indicated in patients with T1-2 tumors with one to three positive axillary lymph nodes who undergo Axillary Lymph Node Dissection (ALND)?
Recommendation 1a: The panel unanimously agreed that the available evidence shows that PMRT reduces the risks of locoregional failure, any recurrence, and breast cancer mortality for patients with T1-2 breast cancer and one to three positive lymph nodes. However, one has to weigh the risk and benefit with PMRT and individualize therapy. Patients with low tumor burden, favorable tumor characteristics, comorbidities, or coexisting conditions and limited life expectancy, may not be appropriate candidates for PMRT, as its potential toxicities outweigh the absolute benefit of PMRT.
Recommendation 1b: The decision to use PMRT should be made in a multidisciplinary fashion through discussion among providers from all treating disciplines, early in a patient’s treatment course, soon after surgery or before or soon after the initiation of systemic therapy.
Recommendation 1c: Decision making must fully involve the patients, so that they are able to weigh the risk/benefits of PMRT, with the best information provided by the treating Health Care Provider.
Clinical Question 2
Is PMRT indicated in patients with T1-2 tumors and a positive Sentinel Node Biopsy (SNB) who do not undergo completion ALND?
Recommendation: Patients with T1-2 tumors with positive sentinel lymph node biopsy, who choose not to have Axillary Lymph Node Disection, should receive PMRT only if there is already sufficient information to justify its use, without needing to know that additional axillary nodes are involved. SNB is generally performed at the time of mastectomy for this patient group, with omission of ALND if the nodes are negative. If the sentinel nodes are positive, ALND is performed. There is increasing controversy about whether ALND is always necessary, if there is limited disease in the affected sentinel nodes. This practice is based on extrapolation of data from randomized trials of patients treated exclusively or predominantly with breast-conserving surgery and whole-breast irradiation or breast plus axillary irradiation.
Clinical Question 3
Is PMRT indicated in patients presenting with clinical stage I or II cancers who have received NeoAdjuvant Systemic Therapy (NAST)?
Recommendation: Patients with axillary nodal involvement that persists after NAST, such as less than a complete pathologic response, should receive PMRT. Observational data suggest a low risk of locoregional recurrence for patients who have clinically negative nodes and receive NAST or who have a complete pathologic response in the lymph nodes with NAST.
Clinical Question 4
Should Regional Nodal Irradiation (RNI) include both the Internal Mammary (IMNs) and supraclavicular-axillary apical nodes when PMRT is used in patients with T1-2 tumors with one to three positive axillary nodes?
Recommendation: Radiation Therapy should generally be administered to both the IMNs and the supraclavicular-axillary apical nodes in addition to the chest wall or reconstructed breast, when PMRT is used for patients with positive axillary lymph nodes.
Postmastectomy Radiotherapy: An American Society of Clinical Oncology, American Society for Radiation Oncology, and Society of Surgical Oncology Focused Guideline Update. Recht A, Comen EA, Fine RE, et al. Published online before print September 19, 2016, doi:10.1200/JCO.2016.69.1188