Locoregional recurrence risk factors in breast cancer patients with positive axillary lymph nodes and the impact of postmastectomy radiotherapy

Background Locoregional recurrence (LRR) after mastectomy reduces the patient’s quality of life and survival. There is a consensus that postmastectomy radiotherapy (PMRT) helps establish locoregional control and reduces LRR in patients with ≥4 metastatic nodes. However, in patients with 1–3 metastatic nodes, the incidence of LRR and the role of PMRT have been the subject of substantial controversy. This study assessed the risk factors for LRR and the efficacy of PMRT in Japanese breast cancer patients with metastatic nodes. Methods This study analyzed 789 cases of invasive breast carcinoma with metastatic nodes from 1998 to 2008. We divided the study population into 4 groups: 1–3 positive nodes with/without chemotherapy and ≥4 positive nodes with/without chemotherapy. Risk factors for LRR were identified and the relationship between LRR and PMRT was analyzed. Results During the median follow-up of 59.6 months, 61 (7.7%) patients experienced LRR. In patients who received chemotherapy, independent LRR risk factors were high nuclear grade, severe lymphatic invasion, vascular invasion, and progesterone receptor-negative status in patients with 1–3 positive nodes, and severe lymphatic invasion and estrogen receptor-negative status in patients with ≥4 nodes. Although patients treated with PMRT had good outcomes, there was no significant difference, and PMRT did not significantly improve the outcome of the patients with all risk factors. Conclusions With systemic therapy and adequate dissection, PMRT by itself was of limited value in establishing locoregional control. The indication for PMRT in patients with 1–3 positive nodes remains controversial.