[Role of population-based cancer registry in cancer epidemiology--epidemiological studies in the Cancer Registration Scheme in Osaka, Japan].

A population-based cancer registration scheme started in three areas in Japan in the 1950s solely for studying cancer incidence in their respective areas. Soon thereafter, several prefectural governments started their own schemes as part of their cancer control programs, effectively expanding the aims of cancer registration: to clarify cancer facts, to elevate the medical care for cancer patients, and to plan and evaluate cancer control programs. The Osaka Cancer Registry (OCR) started in 1962, and has been using epidemiological methods as a tool in constructing its registration scheme, as well as analyzing and utilizing registry data. This report deals with the results obtained in the OCR, classifying these results into four activities of epidemiology. 1. Clarifying cancer facts (descriptive epidemiology): The OCR has been observing incidence, medical care for cancer patients, distribution of cases by clinical stage, and the 5-year relative survival rate, and has estimated the prevalence rate, cured-case rate, and future incidence into the 21st century. Population-based data on histology and multiple cancers collected at the OCR have also contributed to the new approaches in cancer epidemiology. 2. Research on risk factors (analytical epidemiology): The OCR developed a computerized record-linkage system in 1970. This not only made registry work more effective and reliable, but many cohort studies were able to be conducted with relatively little effort and highly reliable results. The cancer case file in the OCR has been linked with the newly prepared data file of the study group, and cancer incidence among the study group has been observed. Finally, cancer risks of possible causal factors in that group have been estimated quantitatively. 3. Evaluation of control programs: Secondary prevention programs (early detection) have been conducted in Japan as major cancer control programs, because effective risk factors were not previously defined. OCR data have been used for estimating sensitivity and specificity of screening tests for various cancers, as well as for evaluating the effect of clinical work on improving survival and on decreasing cancer deaths. 4. Planning future cancer control programs: The OCR has reported on the probable rapid increase of cancer incidence in the 21st century, especially of elderly cancer cases, and cancer cases with poor survival. To control these difficult problems, new cancer programs should be urgently designed and implemented. The authors have recommended that programs be prepared by cancer site, and have already presented a detailed program for lung cancer control.