Survival effect of implementing national treatment strategies for curatively resected colonic and rectal cancer

Background: The surgical management of rectal cancer has changed substantially over the past decade. There are limited data on the long-term outcome of implementing systematic management strategies. Methods: Survival of a national cohort of patients treated surgically for colonic and rectal cancer over a 10-year interval was analysed. All 31 158 patients in Norway diagnosed with adenocarcinoma of the colon and rectum between 1994 and 2003 were identified from the Cancer Registry of Norway and the Norwegian Rectal Cancer Registry. Changes in 5-year relative survival were compared by age, stage and tumour location during the early and late years. Results: The study population included 19 053 patients who had a curative resection. The relative 5-year survival rate significantly improved for both colonic cancer (73.8 versus 78.0 per cent; P < 0.001) and rectal cancer (72.1 versus 79.6 per cent; P < 0.001). The 5-year relative survival was significantly better for rectal than colonic cancer during the late period (P = 0.030). Improved 5-year relative survival was related to better outcomes in patients with positive lymph nodes (67.2 and 62.1 per cent for rectal and colonic cancer respectively; each P < 0.001 versus early period), but not for the subgroup aged over 75 years with lymph node-positive colonic cancer. Conclusion: In this national cohort, survival after curative surgery for colorectal cancer increased significantly after implementation of national management strategies. Improvements were most evident for rectal cancer and in lymph node-positive disease; they were less substantial for colonic cancer and elderly patients (over 75 years). Strategic treatment changes may be warranted for the latter group.