Postmastectomy Radiotherapy: An American Society of Clinical Oncology, American Society for Radiation Oncology, and Society of Surgical Oncology Focused Guideline Update

Authors: Recht, A., Comen, E.A., Fine, R.E., et.al.

Source: J Clin Oncol doi/10.1200/JCO.2016.69.1188

jco.ascopubs.org/content/early/2016/09/15/JCO.2016.69.1188.full.

While PMRT is routinely considered for women with T3 or T4 disease as well as 4 or more positive axillary lymph nodes, the benefits for women with T1 or T2 tumors and 1-3 positive lymph nodes remain in question. Recently, the Early Breast Cancer Trialists’ Collaborative Group published updated data about the effects of Postmastectomy Radiation Therapy (PMRT). The three leading cancer care groups in the US convened a panel to look closely at this study. They found that, for women with T1 or T2 cancer and 1-3 positive nodes, PMRT had significant benefits for recurrence and survival rates. They also noted that the data was mostly from the 1970s and 1980s. Since those decades, the surgical and medical treatment of breast cancer has advanced and recurrence and survival rates have improved. Therefore, it was unclear if PMRT would have the same significant role that it appeared to have 30 years ago.

The panel performed a systematic review of the literature to study the topic. They identified four clinical questions and then formulated recommendations for each one.

Question 1: Is PMRT indicated in patients with T1-T2 tumors with 1-3 positive axillary lymph nodes who undergo full axillary lymph node dissection (ALND)?

Answer: Yes. PMRT in this scenario reduces the risks of recurrence and breast cancer-specific survival. However, it is important to make individual considerations for patients, balancing risks of PMRT with its benefits. For instance, patients with multiple medical problems may not have the same benefit as patients with no other diagnoses. The use of PMRT for all patients should be discussed among all members of a patient’s cancer care team, and the decision making process must fully involve the goals and values of the patient.

Question 2: Is PMRT indicated in patients with T1-2 tumors and a positive sentinel node biopsy (SNB) who do not undergo completion ALND?

Answer: This topic is controversial. Some providers believe that an ALND should be performed for women with positive SNB found during mastectomy. Others regard recent data about positive SNB during lumpectomy and do not perform completion ALND for these patients. The panel provides guidance for both of these philosophies. If there is evidence to warrant the use of PMRT for reasons other than nodal involvement, then it may be used instead of ALND. If the disease information does not support the use of PMRT if all remaining lymph nodes are theoretically clear, then ALND should be performed instead.

Question 3: Is PMRT indicated in patients presenting with clinical stage I or II cancers who have received neoadjuvant systemic therapy (NAST)?

Answer: Yes and probably not. Patients with axillary node disease after NAST should receive PMRT. But, patients with no evidence of nodal disease who receive NAST, and patients with a complete absence of nodal disease after NAST, have a low risk of recurrence and do not need PMRT. Patients in these last two groups should be entered in clinical trials to definitively measure the benefits of PMRT for them.

Question 4: Should regional nodal irradiation (RNI) include both the internal mammary nodes (IMNs) and the supraclavicular-axillary apical nodes when PMRT is used in patients with T1-2 tumors with 1-3 positive axillary nodes?

Answer: Yes. The panel recommends that the IMNs and supraclavicular-axillary apical nodes be included in the field for PMRT.