PRIMARY PROPHYLAXIS WITH G-CSF OF FEBRILE NEUTROPENIA IN BREAST CANCER PATIENTS TREATED WITH ADJUVANT DOCETAXEL AND CYCLOPHOSPHAMIDE

Background: Neutropenia is a common and potentially harmful event in oncological patients exposed to cytotoxic chemotherapy. The primary prophylaxis with Recombinant Human Granulocyte Colony Stimulating Factor (G-CSF) is recommended by international guidelines when the anticipated incidence of febrile neutropenia (FN) is ≥ 20%. Yet data of FN of docetaxel more cyclophosphamide (TC) varies significantly in the literature. Objective: To compare the incidence of ≥ grade 3 (G3) neutropenia and FN with and without G-CSF primary prophylaxis in breast cancer patients treated with adjuvant TC. Methods: Preliminary analysis of a retrospective multicenter cohort of luminal HER2 negative or triple negative stage I-III breast cancer patients treated with adjuvant TC. Neutropenia was graded according do Common Terminology Criteria for Adverse Events version 5.0 and FN was defined as ≥ G3 neutropenia more fever (axillary temperature ≥ 37.8oC). Comparison between the incidence of ≥ G3 neutropenia and FN in the study groups was performed by χ2 and Fisher’s tests (when appropriate). Results: From September 2011 to February 2022 150 patients were included. The median follow-up was 31 months (95%CI 28.6-33.4). The median age was 54 years old (23-99) and the majority were postmenopausal woman (51,3%) with luminal breast cancer (82.6%). The incidence of ≥ G3 neutropenia was 6.6% for the entire population: 13.0% and 1.2% for non-G-CSF and G-CSF groups, respectively (p=0.004). Only one (1,2%) patient presented FN in the G-CSF group versus 7 (10.1%) in non-G-CSF (p=0.024). In this cohort, primary prophylaxis with G-CSF was associated with 9% risk reduction of FN (Odds ratio: 0.91; 95%CI: 0.83-0.98). 80% of patients with ≥ G3 neutropenia were hospitalized, and three (30%) required intensive unit care. Neutropenia/FN led to a delay of adjuvant treatment in 40% cases and to interruption in 30%. Conclusions: Primary prophylaxis with G-CSF in adjuvant treatment of breast cancer with TC was associated with lower rates of ≥ G3 neutropenia and FN. Also, the prevalence of hospitalization within those with neutropenia/FN could justify further studies to evaluate the cost-effectiveness of adopting prophylaxis.