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Summary International differences and trends in cancer survival withinEurope are larger than can reasonably be accounted for by arte-fact, bias or chance. The geographical patterns and trends in sur-vival are often broadly consistent with geographical differences ortrends in the type of cancer, diagnostic investigations or overallinvestment in health care, and for several major cancers, support-ing evidence is available from population-based studies of clinicalinformation. Incomplete ascertainment of cancer cases, particu-larly of long-term survivors, may contribute to some regional andinternational differences in survival, however, and more system-atic information on completeness is required. We may concludethat large international differences in survival do exist for manycancers, but we should be cautious in drawing quantitative orcausal conclusions from observational survival data.We do not yet have a fully satisfactory interpretation of thesedifferences, but we have few alternatives to this type of study if weare to understand the determinants of improved outcome for allcancer patients, and to enable better planning of their health care.The EUROCARE Working Group has developed several strategiesto disentangle the various possible explanations [73]. These includefurther development of high-resolution studies to examine theimpact on survival differences of disease stage, staging techniquesand treatment; and further development of mathematical modelsof cure. Extension of systematic international survival compari-sons to other regions of the world, such as Australia, Canada, Japanand the USA, is also in progress (the CONCORD study) [22].Oncologists and epidemiologists may provide insight into thegeographic differences and trends in survival reported by thisstudy, and may suggest further lines of enquiry. Do we need morerefined studies of survival to monitor progress against cancer andto plan future cancer care? Will such analyses help us quantify theeffect of new treatments arising from recent progress in the basicsciences and genomics on population cancer survival rates? Sub-stantial human and financial resources are required to improve theoutcome of cancer treatment. Will future investments in cancerservices include matching investment to monitor their impact onsurvival and mortality?Earlier diagnosis and prompt, universal access to optimal treat-ment would be expected to reduce international differences incancer survival in Europe. To achieve this, oncologists and healthcare planners will need better information on the comparativeperformance of their health systems. Population-based cancer reg-istries provide some of the information for such comparisons, buttheir traditional output may no longer be sufficient to evaluate theeffectiveness of health systems, and especially to explain geo-graphical differences in survival. In some countries, their role isalso under threat. Confidentiality constraints recently inhibitedthe collection of cancer registration data in the UK [90], and thelinkage of cancer registrations and deaths is currently illegal inEstonia [91]. Both activities are essential for internationally com-parable survival rates. Legal protection for cancer registrationacross Europe will be required.The mission of cancer registries should be reconsidered, and thepriority shifted from classical descriptive epidemiology and geo-graphical pathology toward more analytical monitoring ofprogress against cancer, including the probability of survival andcure, the burden of cancer prevalence, and the late effects oftherapy. Several European studies of this type have been reportedrecently [3, 36, 9294] and others are in progress. Many cancer–registries are developing closer relationships with cancer clini-cians and general practitioners, and some now systematicallycollect detailed clinical information that was collected eitherirregularly or not at all in the past. These developments willimprove the power of population-based cancer data to explain dif-ferences in cancer survival, and should enhance their relevance toclinical practice.European average survival rates are useful for comparativepurposes, but they should not become the goal for cancer controlprogrammes: the benchmark should always be the highest achiev-able survival rates.The aim of exploring geographic differences in cancer survivalis not to establish international league tables or to excite nationalrivalries, but to estimate the range of survival rates, and to identifyregions or countries in which survival could be improved.