Neoadjuvant Therapy in Rectal Cancer Patients with Clinical Stage II to III Across European Countries: Variations and Outcomes.

BACKGROUND:Neoadjuvant therapy improves survival of patients with clinical stage II and III rectal cancer in clinical trials. In this study, we investigated the administration of neoadjuvant radiotherapy (neo-RT) and neoadjuvant chemoradiotherapy (neo-CRT) and its association with survival in resected patients in 2 European countries (The Netherlands and Sweden) and at 3 specialist centers.MATERIALS AND METHODS:Administration of neoadjuvant treatment (all registries) and overall survival after surgery in The Netherlands and Sweden were assessed. Hazard ratios (HRs) were obtained using Cox regression adjusted for potential confounders.RESULTS:A total of 16,095 rectal cancer patients with clinical stage II and III were eligible for analyses. Large variations in administration of neo-RT and neo-CRT were observed. Elderly patients less often received neo-RT and neo-CRT. Patients with stage III disease received neo-CRT more frequently than neo-RT. Administration of neo-RT versus surgery without neoadjuvant treatment was significantly associated with improved survival in The Netherlands (HR, 0.62; 95% confidence interval [CI], 0.53-0.73) as well as in Sweden (HR, 0.79; 95% CI, 0.69-0.90). Administration of neo-CRT was associated with enhanced survival in The Netherlands (HR, 0.62; 95% CI, 0.50-0.78) but not in Sweden (HR, 0.97; 95% CI, 0.80-1.18). The mortality of patients treated with neo-CRT compared with neo-RT showed inconsistent results in population-based centers.CONCLUSIONS:Our results support an association of neo-RT with enhanced survival among stage II and III rectal cancer patients. Comparing neo-CRT with neo-RT, larger variations and inconsistent results with respect to survival were observed across centers.