Does delay of adjuvant chemotherapy affect the clinical outcome in patients with colon cancer?

Abstract

4046 Background: Adjuvant chemotherapy (AC) in patients with stage III colon adenocarcinoma prevents recurrences and improves survival. Although most trials mandate initiation of AC within 8 weeks of resection, the impact of timing of AC is still not clear with few studies reporting conflicting results. We hypothesized that AC commenced within 60 days of resection would increase survival in patients with stage II and III colon cancer. Methods: Patients with newly diagnosed stage II or III colon adenocarcinoma who received fluoropyrimidine based AC in two centers (a private cancer center and a large community hospital) between 2000 and 2007 were included into analysis. Time to adjuvant chemotherapy (TTC), overall survival (OS), and relapse-free survival (RFS) were calculated from the surgery date. Patients were dichotomized into early- (group 1) and late-treatment (group 2) groups using the TTC of 60 days. The demographic, clinical, and laboratory characteristics of patients in two groups were compared using chi-square and t-test. Kaplan-Meier survival curves were constructed employing univariate log-rank test to assess the effects of demographic and clinical characteristics on OS. Then the impact of TTC on OS and RFS was analyzed using a Cox proportional hazard model incorporating the significant factors found in the univariate analysis. Results: 190 patients were eligible for the study (median age: 57 yrs [range 14–84]). 116 patients (61%) were female and 35 patients (18%) had stage II disease. Median TTC was 49 days (range 24–196) and median follow-up was 143 weeks (range 9–451). 134 patients (70%) received AC within 60 days of surgery (group 1) and 56 (30%) received after (group 2). The only difference between the two groups was the higher N stage in group 1. The treating hospital and the N stage were found to be the factors affecting the OS in univariate analysis. Five-year OS for group I was 75.2% as compared to 61.3% for group II (HR 2.11, CI: 1.00–4.45, p=0.049). Five-year RFS for group I was 65.7% as compared to 59.0% for group II (HR: 1.19, CI: 0.65–2.20, p=0.570). Conclusions: Delay of AC more than 60 days after resection is associated with inferior survival in stage II/III colon cancer. No significant financial relationships to disclose.