Malcolm A. Moore

South-West Asia, stretching from Lebanon and Syria in the north, through to Yemen in the south and Iraq in the east, is the home of more than 250 million people. Cancer is already a major problem and the markedly increasing rates for diabetes suggest that the burden of adenocarcinomas will only become heavier over time, especially with increasing obesity and aging of what are now still youthful populations. The age-distributions of the affected patients in fact might also indicate cohort effects in many cases. There are a number of active registries in the region and population-based data are now available for a considerable number of countries. Scientists from the region are also contributing to epidemiological research into the causes of cancer and how to develop effective control programs. The present review covers the relevant PubMed literature and cancer incidence data from various sources, highlighting similarities and variation in the different cancer types, with attempts to explain disparities with reference to environmental factors. In males, the most prevalent cancers vary, with lung urinary bladder or liver in first place, while for females throughout the region breast cancer is the major problem. In both sexes, non-Hodgkins lymphomas and leukemias are relatively prevalent, along with lung in males and thyroid in certain female populations. Coordination of activities within the Arab world, as well as Israel, could bring major benefits to cancer control in the eastern Mediterranean region.

China, Mongolia, Korea and Japan constitute North-East Asia. For reasons of largely shared ethnicity and culture, with various degress of mixed Chinese and Altaic elements, as well as geographical contiguity, they can be usefully grouped together for studies of chronic disease prevalence and particularly cancer. The fact of problems shared in common, with increasing disease rates, underlines the necessity for a coordinated approach to research and development of control measures. To provide a knowledge base, the present review of cancer registration and epidemiology data was conducted. The most frequent cancers in males of North-East Asia are in the lung, liver and stomach, with considerable geographical and temporal variation in their respective prevalences. However, colorectal cancer is also of increasing importance. In females the breast, together with the lung in China, the liver in Mongolia and the stomach in Korea and Japan, are most frequent. Variation in risk factors depends to a large extent on the local level of economic development but overall the countries of the region face similar challenges in achieving effective cancer control.

Since the establishment of the Japanese Foundation for Cancer Research in 1908, Japan has experienced a long history of physicians and researchers playing very active roles in both national and international efforts for cancer control. With the opening of the Japanese Foundation for Cancer Research Cancer Institute and Hospital in 1934 and the National Cancer Center in 1962, followed by Aichi Cancer Center in 1964 and then gradually Prefectural Centers across the country, the populace is well endowed with specialist research and clinical facilities. Under the Cancer Control Act, implemented in 2007, these are now being complemented by a network of specialist hospitals also involved in efforts to improve training and cancer registration as well as standardization of cancer treatment. Regional cancer registries have been active since the 1960's and national programs for cervical and stomach cancer screening were introduced in 1984. Subsequently, such early detection efforts have been added for the lung, colorectal, endometrial and breast cancers. There are a large number of academic scientific societies holding regular research meetings and focusing on all the different aspects of cancer control. In addition, there are non-government organizations like the Foundation for Promotion of Cancer Research, the Princess Takamatsu Cancer Research Foundation, the Sapporo Cancer Seminar Foundation and the Hiroshima Cancer Seminar Foundation, all sponsoring international research meetings and other efforts. Other foundations have been established, for example by patient support groups, and policy research and strategic planning are now high priorities of the Government. Japan also continues to contribute to international efforts though its membership in the WHO and the International Agency for Research on Cancer (IARC), as well as through individual memberships in the International Union Against Cancer (UICC).

The Arab world, stretching from Lebanon and Syria in the north, through to Morocco in the west, Yemen in the south and Iraq in the east, is the home of more than 300 million people. Cancer is already a major problem and the lifestyle changes underlying the markedly increasing rates for diabetes mean that the burden of neoplasia will only become heavier over time, especially with increasing obesity and aging of what are now still youthful populations. The age-distributions of the affected patients in fact might also indicate cohort effects in many cases. There are a number of active registries in the region and population-based data are now available for a considerable number of countries. A body of Arab scientists is also contributing to epidemiological research into the causes of cancer and how to develop effective control programs. The present review covers the relevant PubMed literature and cancer incidence data from various sources, highlighting similarities and variation in the different cancer types, with attempts to explain disparities with reference to possible environmental factors. In males, the most prevalent cancers vary, with lung, urinary bladder or liver in first place, while for females throughout the region breast cancer is the greatest problem. In both sexes, non-Hodgkins lymphomas and leukemias are relatively frequent, along with thyroid cancer in certain female populations. Adenocarcinomas of the breast, prostate and colorectum appear to be increasing. Coordination of activities within the Arab world could bring major benefits to cancer control in the eastern Mediterranean region.

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.

The great variability in gastric cancer rates across Asia, with very high incidences in Japan and Korea, and exceedingly low incidences in ethnic Malays, whether in Malaysia or Indonesia, appears largely due to variation in Helicobacter pylori infection rates. While between 2% and 10.6% of gastric cancers in a recent Japanese survey were considered to be negative for bacterial infection on the basis of seropositivity and H. pylori-dependent mucosal atrophy, it is notoriously difficult to preclude past infection. The situation is greatly complicated by reported differences in the etiology of gastric cardia and non-cardia cancers. In the Western world there do appear to be tumours arising close to the esophageal-gastric junction which are not related to H. pylori and associated inflammation, but in most Asian populations these appear to be very rare. Therefore preventive efforts, and particularly screening, should be focused on markers of bacterial infection, with avoidance of unnecessary exposure to X-ray radiation.

C-reactive protein (CRP) is one of the acute-phase proteins in inflammation and CRP serum concentrations are therefore of interest. Data for high-sensitivity CRP (hs-CRP) with a low detection limit of approximately 0.04 mg/L have become available over the past decade and research has shown a link between high concentrations of hs-CRP and obesity as well as smoking. Expanded adipose tissue is in fact known to secrete proinflammatory cytokines which enhance hepatic synthesis of CRP. Moderate alcohol consumption and high physical activity have been associated with low levels of hs-CRP, but the evidence in these cases is not conclusive. It has been suggested that hs-CRP is an independent marker of the risk of cardiovascular disease, but the predictive capacity remains controversial. However, many prospective studies have observed increased risk of type 2 diabetes mellitus associated with high concentrations of hs-CRP, independent of obesity and other cardiovascular risk factors. On the other hand, no measurable increase in the risk associated with high levels of hs-CRP was observed with multivariate adjustment in several studies. A number of authors have reported that high concentrations of hs-CRP are associated with increased risks of colorectal and other cancers, but the findings again are inconsistent. Diet and hs-CRP are also of increasing research interest. High intakes of carotenoids and vitamin C, but not of vitamin E, seem to decrease the level of circulating hs-CRP. In addition, high consumption of vegetables and fruit are associated with lower levels of circulating hs-CRP, perhaps by exerting anti-inflammatory effects. Both mechanistic and epidemiologic studies regarding dietary factors and low-grade inflammation are necessary to add to our knowledge of dietary influence on chronic disease development.

Tobacco smoking is an unequivocal risk factor for cancers of the larynx, lung, pancreas and urinary bladder. Whereas African-Americans demonstrate higher laryngeal, lung and pancreatic cancer rates than their Caucasian-American counterparts, they paradoxically have only approximately half of the urinary bladder incidences. One possible explanation is their N-acetyltransferase (NAT) status, since this enzyme is responsible for metabolism of arylamines in smoke and blacks are reported to have a higher rate for rapid acetylation than whites. However, other tobacco-related cancers are also linked to slow acetylation so that African-Americans might therefore also be expected to have lower incidences of other tobacco-related cancers. The present investigation was conducted with data from Cancer Incidence in Five Continents Vol VIII to assess whether there might be correlations between incidence rates for four major cancers across registries in the United States. Cluster analysis demonstrated clear separation of the white and black populations for all states, and significant correlations were observed between bladder and laryngeal cancers, and also for lung and laryngeal cancers, for both Blacks and Whites. Striking similarities in the plots for urinary bladder incidence against all three of the other cancers suggests the existence of a factor specific to the bladder. A review of black-white ratios for cancer incidences in all major body sites in both sexes and the published literature for NAT polymorphisms provided evidence that this might indeed be arylamine exposure, although other factors could also be involved.