Who should be considered for FOLFOX adjuvant chemotherapy? An analysis of Dukes B colorectal cancer in a Royal Marsden Hospital randomized trial

Abstract

3559 Background: Based on the positive results of adjuvant fluoropyrimidine chemotherapy in Dukes B colorectal cancer in the QUASAR trial it is expected that more patients with this stage of disease will be offered chemotherapy. Furthermore the MOSAIC study has indicated a role for combination chemotherapy with FOLFOX in these patients. Thus we have conducted an analysis of the disease-free and overall survivals (DFS and OS) of the Dukes B patients from our multicentre randomized trial which compared two 5-FU based regimens (Mayo regimen versus protracted venous infusion) to determine the influence of other adverse clinical and histological prognostic factors on outcome. Methods: Patients were considered high risk if ≥1 of the following was present: poorly differentiated or mucinous tumours; T4 stage; extramural venous invasion; presentation with either perforation or obstruction. Results: Between 1993 and 2003, a total of 801 patients received treatment within the study. Of these, there were 277 Dukes B patients from RMH who were high (n=94) or low (n=183) risk. The proportion of patients from both treatment arms in both groups was well matched. The median follow-up at the time of analysis was 6.2 years. There have been 53 relapses and 58 deaths in the patient cohort to date.The 3-year DFS for the high and low risk groups was 70.9% [95% CI: 60.5–79.0%] and 87.9% [95% CI: 82.2–91.9%] respectively (HR=1.85 [95% CI: 1.13–3.04; p=0.0078]).The 5-year OS for the high and low risk groups was 77.6% [95% CI: 67.5–85.0%] and 86.7% [95% CI: 80.6–90.9%] respectively (HR=1.69 [95% CI: 0.97–2.96; p=0.0474]). In comparison, the 5-year OS for the entire group of Dukes C patients entered in the study was 67.3% [95%CI: 62.4–71.7%] respectively. Conclusions: Patients with Dukes B colorectal cancer who had at least one adverse prognostic feature, who received adjuvant chemotherapy with 5-FU alone, had a significantly worse OS (5-year OS 77.6% versus 86.7%) and DFS compared to those who did not have any such factors. This reinforces the case for adjuvant chemotherapy with FOLFOX in this group of patients. No significant financial relationships to disclose.