Background: Studies have demonstrated that patients with stage III colon cancer who receive adjuvant FOLFOX (5-fluorouracil and oxaliplatin) chemotherapy experience an improved disease-free (DFS) and overall survival (OS). However, the magnitude of benefit among patients who discontinue FOLFOX early is not well known. We sought to examine the rate of FOLFOX treatment completion, determine the factors associated with adherence, and explore the relationship between duration of FOLFOX treatment and survival.
Patients and methods: We analyzed patients diagnosed with stage III colon cancer from 2006 to 2010 and initiated at least 1 cycle of adjuvant FOLFOX at any 1 of 5 regional cancer centers in British Columbia. Logistic regression models were constructed to determine the clinical factors associated with treatment completion, which was defined as receipt of ≥ 10 cycles of FOLFOX. Kaplan-Meier methods and Cox regression that accounted for known prognostic factors were used to evaluate the relationship between early FOLFOX discontinuation and DFS and OS.
Results: We identified 616 patients: median age of 62 years (range, 26-80), 321 (52%) men, 536 (87%) with T3/4 tumors, and 245 (40%) with N2 disease. Among them, 183 (30%) received < 10 and 433 (70%) received ≥ 10 cycles. Adjusting for covariates, female sex and the absence of obstruction or perforation were each associated with receiving ≥ 10 cycles of FOLFOX (odds ratio [OR], 1.61; 95% confidence interval [CI], 1.12-2.32; P = .01 and OR, 1.82; 95% CI, 1.08-3.05; P = .02, respectively). In multivariate analyses, early discontinuation of FOLFOX did not affect DFS or OS (hazard ratio [HR], 1.16; 95% CI, 0.82-1.63; P = .40 and HR, 1.07; 95% CI, 0.70-1.61; P = .76, respectively).
Conclusion: Early discontinuation of FOLFOX was not associated with differences in survival outcomes, lending support to clinical trials that are under way to evaluate the efficacy of shorter durations of therapy.
Keywords: Adherence; Adjuvant chemotherapy; Completion; FOLFOX; Treatment duration.
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