A Pilot Study of Extended Adjuvant Therapy with Metronomic Docetaxel for Patients with Operable Triple-Negative Breast Cancer

BACKGROUND: Triple-negative breast(TNBC) cancer is a molecular subtype of breast cancer with poor prognosis and did not get approved targeted therapy till now. In the last years, metronomic chemotherapy (mCTH) was investigated to improve treatment outcomes in TNBC patients both in early and metastatic setting due to its anti-angiogenic and immune-stimulatory mechanisms. The aim of this study is to evaluate the efficacy and safety of extended adjuvant chemotherapy with metronomic docetaxel for patients with operable TNBC. METHODS: 31 women with clinically and pathologically proved operable TNBC, either node-negative or node-positive with tumor size ≥ 0,5 cm were enrolled after finishing the primary standard of care treatment. The patients were subjected to extended adjuvant therapy for 6 months with metronomic low dose docetaxel with starting dose of 15mg/m(2) in weekly bases for 4 weeks then the dose was escalated to 20 mg/m(2 )once per week if there were no side effects. RESULTS: After a median follow up of 36 months (range 6-52), 24 patients (77.4%) were still alive. During the period of follow-up, 12 patients (38.7%) showed disease relapse and 19(61.3%) cases remain free of the disease. The estimated mean of DFS in our study was 38.26 months (95%CI; 31.87 – 44.65) with 2 and 3 years DFS rate of 70.5 % and 56.4% respectively while the estimated mean of OS was 43.75 months (95% CI; 38.35 – 49.16) with 2 and 3 years OS rates 83.3% and 78.1% respectively, Generally the treatment was tolerated with mild to moderate hematological and non hematological adverse events, all are grade 1,2 and treatment-related deaths were not observed. CONCLUSION: Extended adjuvant treatment for 6 months with metronomic docetaxel after the primary standard of care therapy was tolerated and has an encouraging survival benefit in patients with operable TNBC and these results need further evaluation in randomized control studies.