Establishment of an Asian Cancer Registry Network - problems and perspectives.

Cancer registration is the base for our understanding of the burden of neoplastic disease in our populations at the local, regional and national levels. Comparability of data is essential for interpretation and this in turn depends on standardization of methodology and the diagnostic and other criteria applied. If this is to be achieved across Asia, some form of international organization is clearly necessary. The question therefore should be whether the existing arrangement is adequate, and if this is not the case how a network in Asia might be established with due consideration of aims and attainable objectives. The present commentary focuses on the contributions made by the International Association of Cancer Registries (IACR) and individual country-based or region-based associations already active in Asia. Building on an analysis of the present status in Asia, as well as experience of the European Network of Cancer Registries (ENCR) and the North American Association of Central Cancer Registries (NAACCR), potential problems and possible solutions are here reviewed, with coverage of both organizational and financial constraints. An argument is presented here that there is a rationale for some form of an Asian Network of Cancer Registries, supported by the International Agency for Research on Cancer (IARC) and the UICC-Asian Regional Office, working alongside the IACR and existing national organizations and research institutes.

What do cancer registry and household expenditure data in Japan tell us about variation in tumour burden ?

Data from the total of six Japanese Cancer Registries presently reporting to Cancer Incidence in Five Continents demonstrate marked variation in relative prevalence of cancers at particular sites, despite the genetic homogeneity of the Japanese population. Thus either major differences in registry procedures or local environment must be playing an important role and since the variation is clearly changing with time, the former must be considered likely. Over the last 25 year period, incidence rates for the esophagus have been generally increasing in Japan, except in Miyagi where they have been persistently high. Stomach cancer rates are on the decrease, although the trend is not so clear in Yamagata and Hiroshima, while colon and rectal cancers have both demonstrated consistent increment throughout the period surveyed, with a remarkable correlation between the two sites evident on cross-registry comparisons. Continued increases have also been apparent in lung, kidney, urinary bladder and prostate cancers in males and in breast, endometrium and thyroid neoplasms in females. Cervical cancer, in contrast, is decreasing, although a plateau may now have been reached in Miyagi. In the hepatopancreatic axis, patterns have generally showed elevation followed by a recent reduction, although without correlations among liver, gallbladder and pancreas rates at the cross-registry level. Common lifestyle factors may to some extent underly the increases seen in colon, breast, urinary bladder and thyroid incidence rates, given the significant relations apparent for these in the latest data across registries. Whether analysis of variation in dietary intake and exposure to other risk factors, for example using data for household expenditure, may provide clues to explaining the variation apparent across Japan is a question warranting further consideration. If so an expanded role for the cancer registry could well be envisaged.

Comparison of Japanese, American-Whites and African-Americans--pointers to risk factors to underlying distribution of tumours in the colorectum.

Relative incidence rates for colon and rectal cancer vary greatly between populations in the world. While Japanese have historically had low prevalence, immigration to the United States has now resulted in equal if not higher rates than in Caucasian- or African-Americans. Furthermore, recent data from some population-based registries in Japan itself are also pointing to particularly high susceptibility. Of particular interest is the fact that Japanese in both the home country and the US in fact have far higher rates for rectal cancer than the other two ethnic groups. An intriguing question is whether they might also demonstrate variation from Caucasian- and African-Americans in the relative incidence rates for proximal and distal colon cancers, given the clear differences in risk factors like diabetes, physical exercise, smoking, alcohol consumption, meat and fish intake and calcium exposure which have been shown to operate in these two sites. A comprehensive epidemiological research exercise is here proposed to elucidate ethnic variation in colorectal cancer development, based on cross-cancer registry descriptive and case control approaches. It is envisaged that additional emphasis on screened populations should further provide important insights into causal factors and how primary and secondary prevention efforts can be optimized.