Adjuvant chemotherapy and survival outcome in node-negative breast cancer with a 21-gene recurrence score of 26-30.

Aim: To investigate the benefit of chemotherapy among early-stage breast cancer patients with 21-gene recurrence scores of 26-30. Methods: We identified 3754 patients in the Surveillance, Epidemiology, and End Results database. Results: 57.6% of the patients received adjuvant chemotherapy. Patients with higher tumor grade, larger tumors and younger age were more likely to receive chemotherapy. The receipt of chemotherapy was independently associated with better breast cancer-specific survival than in patients without chemotherapy before (p = 0.016) and after (p = 0.043) propensity score matching. The sensitivity analyses showed that survival gain was pronounced in patients with poorly differentiated or undifferentiated disease. Conclusions: Adjuvant chemotherapy improves the outcome for early-stage breast cancer with 21-gene recurrence score of 26-30, especially for patients with high-grade tumors.