Timing of Adjuvant Chemotherapy and Survival in Patients with Stage II/III Rectal Cancer

Background: Treatment guidelines in the 1990s established surgery followed by chemoradiotherapy as the standard treatment for stage II/III rectal cancer. Our aim was to investigate the association between the timing of adjuvant treatment and patient survival in practice and identify demographic/clinical factors associated with treatment patterns. Methods: All residents of Alberta diagnosed with stage II/III rectal adenocarcinoma in 2000-2005 who had surgery were included in the study. Demographic and clinical data were obtained from the Alberta Cancer Registry and linked to hospital data and socioeconomic data from the 2001 Canadian Census. Overall and cancer-specific hazard ratios of death were estimated using Cox proportional hazards models. Results: 1243 patients were included in the study; 636 (51%) patients received treatment consistent with guidelines. Patients who received adjuvant chemotherapy 12 16 weeks after surgery or more than 16 weeks/ did not receive it had a 43% and 58% higher risk of rectal cancer death, respectively, compared to those who received it within 8 weeks of surgery. Conclusion: Adjuvant chemotherapy for stage II/III rectal cancer should be initiated within 12 weeks after surgery to maximize treatment benefits. Efforts to increase the proportion of patients treated within 12 weeks after surgery are needed.