Abstract
PURPOSE: To look at how the absolute neutrophil count (ANC) is used by community oncologists as the main factor in ordering adjuvant mFOLFOX6 for colorectal cancer. This study reports on how this decision impacts chemotherapy delays, effects received dose intensity (RDI), and increases the use of granulocyte-colony-stimulating factor (G-CSF). METHODS: A retrospective chart review was conducted for all patients receiving adjuvant mFOLFOX6 for colorectal cancer at a two-site community hospital in Toronto, Ontario, Canada, between July 2013 and March 2019. Seven physicians treated 140 patients, who made 1636 clinic visits to receive 1461 cycles of prescribed chemotherapy. RESULTS: The mean ANC per physician associated with a decision to give chemotherapy ranged from 1.05×10(9)/L (95% CI 0.98-1.13×10(9)/L) to 1.5x10(9)/L with a decision to delay if the ANC was lower. Subsequent cycles were then supported by G-CSF with very similar ANC decision levels for dose delay. Physicians were more likely to prescribe chemotherapy with higher pretreatment ANC, r=0.3 (p<0.000). G-CSF was used in 24.6% of cycles and usage had grown to 44.2% by the 12th cycle; physician use ranged from 0.36% to 54.2% of cycles. Secondary prophylaxis was the indication in 94.7% of cases. There was an inverse relationship between the frequency of G-CSF use and the RDI of continuous infusion 5FU, r=-0.26 (p<0.001). There were delays for 8.8% of visits for cycles not supported by G-CSF and, surprisingly, 15.9% of visits for cycles supported by G-CSF. Neutropenia caused 61.6% of delays for chemotherapy cycles not supported by G-CSF and 44.1% for cycles supported by G-CSF. CONCLUSION: Physicians required a pretreatment ANC of 1.05-1.5×10(9)/L before prescribing mFOLFOX6 chemotherapy. When ANC was low, a dose delay and secondary prophylaxis with G-CSF failed to consistently achieve the much sought after ANC. This then caused more delay, reduced RDI and increased expense for both patients and the system. Fewer delays, less G-CSF and increased RDI would have resulted with reduced reliance on ANC and adoption of chemotherapy dose reduction.