Effects of reduced dose intensity of modified FOLFOX6 in patients with metastatic or recurrent colorectal cancer

The current study was conducted to retrospectively investigate the effects of reducing average relative dose intensity (ARDI) in response to adverse events on time to treatment failure (TTF) and overall survival (OS) in patients with metastatic or recurrent colorectal cancer receiving modified FOLFOX6 (mFOLFOX6) therapy between January 2006 and May 2010. Patients were divided into two groups based on ARDI: those with an ARDI of 85% or more (ARDI maintained; n = 12) and those with an ARDI of less than 85% (ARDI reduced; n = 37). In the ARDI-reduced group, out of a total of 402 treatment courses conducted, 25.9% involved treatment delays and 8.2% involved dose reductions, and the incidence rate of treatment delay was significantly higher than that of dose reduction (p < 0.001). Hematological toxicity was the main reason for both treatment delays and dose reductions. Reduced ARDI by dose reduction effectively prevented any increase in the severity of neutropenia and the treatment delays in the next courses, suggesting that the dose reductions were appropriately performed. Median TTF in the ARDI-maintained and ARDI-reduced groups was 5.2 and 5.8 months, respectively (p = 0.225). Median OS was 15.5 months and 33.9 months in the ARDI-maintained and ARDI-reduced groups, respectively (p = 0.347). These findings suggested that reductions in ARDI of mFOLFOX6 therapy for metastatic or recurrent colorectal cancer due to treatment delays and dose reductions in response to adverse events do not necessarily lead to shortened TTF and OS.