620 - Impact of the Interval Between Surgery and Adjuvant MFOLFOX6 on Survival of Colon Cancer Patients

Abstract

ABSTRACT Background Adjuvant chemotherapy with the association of Oxaliplatin and Fluoropyrimidines has shown to reduce recurrence risk and improve survival in stage III colon cancer patients in comparison to Fluoropyrimidines alone. The ideal timing for the start of adjuvant chemotherapy has not been defined. Our aim was to determine the impact of the interval between surgery and the start of adjuvant chemotherapy on survival of colon cancer patients. Material and methods Retrospective cohort study, in a Portuguese cancer centre, of colon cancer (CC) patients treated with mFOLFOX6 in the adjuvant setting, from September 2004 till November 2009. Two groups of patients were defined according to the timing of adjuvant chemotherapy (CT): ≤ 8weeks or >8 weeks after surgery. Efficacy was evaluated by overall survival (OS) and disease-free survival (DFS). Hazard ratios and 95% confidence intervals were calculated with the use of the Cox proportional hazards model. Results Two hundred and seventy seven patients were treated with adjuvant mFOLFOX6 and followed for a median time of 45 months. Median age was 62 years (28-79); 57% were male and 77% had stage III CC. Median time to the start of CT was 8 weeks (P25 = 7, P75 = 10). The group of patients that started CT > 8 weeks after surgery was older (mean age: 62 vs 59 years, p = 0.001) and tended to accomplish lower relative dose-intensity of Oxaliplatin and 5-Fluorouracil (69,5% vs 72% and 73% vs 76%, respectively; p > 0.05). There was a tendency to lower OS and DFS in the group that started CT >8 weeks after surgery. At 3 years, the probability of OS was 83% vs 90% (p = 0.118), and DFS: 75% vs 77% (p = 0.751). Multivariate analysis showed that the interval between surgery and the start of adjuvant CT had no impact in OS nor DFS. Conclusions Our data point to a tendency to better survival when CT is started within 8 weeks of surgery, strengthening the need for a timely referral of patients to adjuvant treatment. The small sample size and the short follow-up might explain why we were unable to find statistical significance in this association. Disclosure All authors have declared no conflicts of interest.