MO3-8-3 Revisit the risk factors of recurrence in node involved HER2-positive breast cancer.

While pertuzumab was added to adjuvant therapy for high-risk HER2-positive breast cancer according to APHINY trial, definition of "high risk of recurrence" is still unclear. Because neoadjuvant chemotherapy (NAC) including anti-HER2 drugs showed potent efficacy to achieve pCR and better survival, one lymph node metastases may show survival outcomes equivalent to node-negative cases. Hence, we examined the risk factors of recurrence in HER2-positive breast cancer and determined whether one lymph node metastasis after NAC is true predictor of recurrence. From May 1993 to March 2017, patients who underwent radical mastectomy/partial mastectomy after NAC for breast cancer in our institution were retrospectively examined. Among those patients, HER2-positive patients were 253, 23% of all patients. Breast cancer recurrence occurred in 46 (18.2%) of HER2-positive patients who underwent NAC and radical mastectomy. Multivariate analysis was performed on tumor size, lymph node metastasis, hormone receptor, Ki-67, preoperative chemotherapy regimen for recurrence risk factor. The risk of recurrence was significantly higher in one lymph node metastasis group than in the node-negative group (HR 6.157, p=.0006, 95%CI 2.175-17.435). Likewise, the risk of recurrence was significantly higher in the group with two or more lymph node metastases than in the node-negative group (HR 3.877, p=.0107, 95%CI 1.370-10.972). The presence of even one lymph node metastasis was suggested as a risk factor of recurrence, likely representing metastatic potential of the disease. [ABSTRACT FROM AUTHOR]