Neutropenia and relative dose intensity on adjuvant FOLFOX chemotherapy are not associated with survival for resected colon cancer.

Purpose: Adjuvant folinic acid, fluorouracil, and oxaliplatin (FOLFOX) chemotherapy for resected high-risk colon cancer is associated with a low risk of febrile neutropenia (FN). Neutropenia, however, is a common cause of dose modification or delay with unknown consequences on outcomes. We examined the effect of neutropenia-related and other dose-limiting toxicities and relative dose intensity of oxaliplatin and 5-FU, on relapse-free and overall survival in patients treated with FOLFOX chemotherapy for resected high-risk colon cancer.

Methods: A chart review was conducted on patients treated at the British Columbia Cancer Agency receiving ≥1 cycle of mFOLFOX6 chemotherapy for resected stage II or III colon cancer between January 1, 2006, and December 31, 2007. Relapse-free survival (RFS) and overall survival (OS) were analyzed by the Kaplan-Meier method.

Results: One hundred fourteen patients (median age 59 years, 44 % male, 98 % stage III, median follow-up 5.2 years) were included. Ninety percent of the patients experienced any dose-limiting toxicity (DLT), while 58 % of the patients had a neutropenia-related DLT. There were no documented episodes of FN. Granulocyte colony-stimulating factor (GCSF) was used in 10 % of the patients. Median relative dose intensity (RDI) was 81 and 85 % for oxaliplatin and 5-FU, respectively. Oxaliplatin and 5-FU RDI were not associated with RFS or OS when analyzed as continuous variables or categorically. Grade II or grade III/IV neutropenia compared to no neutropenia was not associated with RFS or OS.

Conclusions: DLTs affect the majority of patients on adjuvant FOLFOX for high-risk colon cancer, but RFS and OS do not appear to be affected by the associated lower RDI of oxaliplatin and 5-FU.