Locoregional relapse is a strong prognostic indicator of distant metastatic progression in breast cancer patients after negative sentinel lymph node biopsy

PURPOSE Sentinel lymph node biopsy is routinely used in breast cancer patients with clinically negative axillary lymph nodes. Locoregional relapses after negative sentinel lymph node biopsy are infrequent, occurring in up to 3% of patients. METHODS Six thousand and eight patients underwent breast cancer surgery in our center between 2006 and 2015. We analyzed 1466 patients with negative sentinel lymph node biopsy and no prior systemic treatment. Mastectomy without irradiation was used in 25.4% of these patients and breast-conserving surgery with adjuvant radiotherapy in 74.6%. Forty-seven (3.21%) locoregional relapses were identified within a median of 51 months (10-138 months). The molecular type was analyzed as a risk factor for locoregional relapses and distant metastases. The locoregional relapse location was then analyzed as a risk factor for distant metastases. RESULTS Triple-negative breast cancer (P = .003), age <40 year (P = .007), multifocality (P = .011), and mastectomy (P < .0001) were risk factors for locoregional relapses. Patients who developed locoregional relapses more frequently developed distant metastases (P < .0001). The distribution of molecular types did not differ significantly in patients with locoregional relapses and distant metastases, concentrating in triple-negative and Luminal B tumor cases with distant metastases in almost 58% of cases, while not occurring in Luminal A patients. The locoregional-to-distant metastasis interval was shorter in cases of chest wall and lymph nodes relapse compared with breast-only relapse locations(P = .028). CONCLUSION Molecular type, especially triple-negative, young age, mastectomy without adjuvant irradiation, and multifocality are risk factors for locoregional relapse in sentinel lymph node biopsy negative breast cancer patients. Locoregional relapse is an important risk factor for developing distant metastasis, except in Luminal A breast cancer patients and those who suffer from breast-only relapse.