Mastectomy is still an appropriate treatment for many patients with primary breast cancer. In countries without radiotherapy units or with inadequate facilities for QA, it remains the standard surgical treatment, even for patients who are diagnosed at an early stage. PMRT generally includes radiation of the chest wall and regional lymphatics, and it has been demonstrated that PMRT drastically reduces locoregional recurrences and improves overall survival in patients with high-risk breast cancer. The major risk factors for locoregional recurrence are axillary lymph node metastases and the number of involved lymph nodes, although there is no consensus on the number or percentage of involved lymph nodes needed to apply PMRT.
It is widely accepted that all patients with an adequate axillary dissection and lymph nodes should receive postoperative chest wall and supraclavicular field radiation, because the majority of recurrences are observed in those locations. Randomized trials and a meta-analyses have reported improved overall survival rates as well as improved local control for patients who have 1 to 3 positive lymph nodes. These patients should be considered for chest wall and supraclavicular field irradiation, and priority should be given to patients who have 4 positive lymph nodes for limited resource settings. Routine axillary irradiation is used only for patients who have not undergone adequate axillary dissection. Irradiation of the axilla, in general, is not recommended because of the low incidence of axillary recurrence and the increased risk of arm edema for patients who have <10 involved lymph nodes.
Internal mammary lymphatics are relatively uncommon sites for recurrences; and, if cardiac toxicity is a concern, then irradiation of the internal mammary chain is not recommended. The results from randomized trials are needed. Internal mammary chain irradiation is recommended for patients with clinically or pathologically positive internal mammary lymph nodes. Radiation therapy of internal mammary lymphatics should be considered if the primary tumor is located in the inner quadrant and if other adverse risk factors are present. Irradiation of the chest wall is recommended for patients with lymph node-negative breast cancer who have a primary tumor >5 cm in greatest dimension and/or positive surgical margins despite the contradictory
results from retrospective series.
This applies especially to patients in limited-resource settings, who usually present with larger tumors, who may not receive sufficient systemic treatment, and whose local recurrences may be incurable. Chest wall irradiation also is considered for patients with negative axillary lymph nodes who have multiple adverse factors (ie, primary tumor >2 cm, close surgical margins, lymphovascular invasion, grade disease, premenopausal status, or unavailability of systemic treatment).