BACKGROUND AND OBJECTIVES: In stage III colonic cancer, time from surgery to start of adjuvant chemotherapy may influence survival. In this study, we evaluated the effect of timing of adjuvant therapy on survival.

METHODS: Database study from the Danish Colorectal Cancer Group's national database. Data on patients with stage III colonic cancer operated between January 1, 2005 and August 31, 2012 were retrieved. Perioperative variables, surgical modality, and time to adjuvant therapy (<4, 4-8, or >8 weeks) were evaluated and Cox regression was performed to identify factors influencing survival.

RESULTS: The final population included 1,827 patients scheduled for adjuvant chemotherapy. Adjuvant therapy started within 4 and 8 weeks improved survival when compared to start later than 8 weeks (HR [95%CI]: 1.7 [1.1-2.6]; P = 0.024 and 1.4 [1.07-1.8]; P = 0.013, respectively), whereas there was no significant difference in survival with start after 4 versus 8 weeks (1.2 [0.8-1.8]; P = 0.37).

CONCLUSIONS: Survival increased when adjuvant therapy was started within 8 weeks after surgery for stage III colonic cancer.