Survival Outcomes of Different Treatment Methods for the Ipsilateral Breast of Occult Breast Cancer Patients with Axillary Lymph Node Metastasis: A Single Center Experience

PURPOSE This study compared the survival outcomes of different treatment methods for the ipsilateral breast of occult breast cancer (OBC) patients with axillary lymph node metastasis. METHODS A retrospective study was conducted in which forty OBC patients with axillary lymph node metastasis were identified out of 15,029 patients who had been diagnosed with a primary breast cancer at between 1992 and 2010. The patients were categorized into three treatment groups based on ipsilateral breast management: breast-conserving surgery (BCS) (n=17), mastectomy (n=12), and nonsurgical intervention with or without radiation therapy (No surgery with or without radiation therapy [No Op±RT]) (n=11). All patients underwent axillary lymph node dissection. Cases were evaluated based on treatment and potential prognostic factors with respect to overall survival (OS) and disease-free survival (DFS). RESULTS During the follow-up period (median follow-up of 71.5 months), the overall OS and DFS were 76.9% and 74.9%, respectively. The 5-year treatment-specific OS was 72.0% for the BCS group, 74.0% for the mastectomy group, and 87.5% for the No Op±RT group (log-rank p=0.49). The 5-year DFS was 70.6% for the BCS group, 66.7% for the mastectomy group, and 90.9% for the No Op±RT group (log-rank p=0.36). Recurrence rates for the BCS and No Op±RT groups were 5.9% and 18.2%, respectively. Histologic grade and lymph node status were inversely correlated with DFS (log-rank p=0.04 and p<0.01, respectively). CONCLUSION There was no difference in survival outcomes between the three treatment methods for the ipsilateral breast (mastectomy, BCS, and No Op±RT) of OBC patients with axillary lymph node metastasis. A large-scale multicenter study is needed to validate the results from this small retrospective study.