Understanding variations in survival for colorectal cancer in Europe: a EUROCARE high resolution study

Background-Marked differences in population based survival across Europe we re found for colorectal cancers diagnosed in 1985-1989. Aims-To understand the reasons for these differences in survival in a new a nalysis of colorectal cancers diagnosed between 1988 and 1991. Subjects-A total of 2720 patients with adenocarcinoma of the large bowel fr om 11 European cancer registries (CRs). Methods-We obtained information on stage at diagnosis, diagnostic determina nts, and surgical treatment (not routinely collected by CRs) and analysed t he data in relation to three year observed survival, calculating relative r isks (RRs) of death and adjusting for age, sex, site, stage, and determinan ts of stage. Results-Three year observed survival rates ranged from 25% (Cracow) to 59% (Modena), and were low in the Thames area (UK) (38%). Survival rates betwee n registries for "resected" patients varied less than those for all patient s. When age, sex, and site were considered, RRs ranged from 0.7 (95% confid ence intervals (CI) 0.6-0.9) (Modena) to 2.3 (95% CI 1.9-2.9) (Cracow). Aft er further adjustment by stage, between registry RR variation was between 0 .8 (95% CI 0.6-0.9) and 1.8 (95% CI 1.5-2.2). Inter-registry RR differences were slightly reduced when the determinants of stage (number of nodes exam ined and liver imaging) were included in the model. The reduction was marke d for the UK registries. Conclusions-The wide differences across Europe in colorectal cancer surviva l depend to a large extent on differences in stage at diagnosis. There are wide variations in diagnostic and surgical practices. There was a twofold r ange in the risk of death front colorectal cancer even after adjustment for surgery and disease stage.