Cancer Incidence in Thailand, 1988_19911

Results from three cancer registries (Chiang Mai, Khon Kaen, and Songkhla) in different regions of Thailand and from a cancer survey in the population of Bangkok during the years 1988-1991 are presented, together with an estimate of the incidence of cancer for the country as a whole. Overall, liver cancer is the most frequent malignancy, but there are large regional differences in incidence and in histological type, with very high rates of cholangiocarcinoma in the northeast (associated with endemic opisthorchiasis) but a more even distribution of hepatocellular carcinoma. Lung cancer is second in frequency, with the highest rates in northern Thailand, where the incidence in women (Age Standardized Rate, 37.4 per 100,000) is among the highest in the world. A link with tobacco smoking is suggested by similarly raised rates, especially in women, for cancers of the larynx and pancreas. Cervical cancer is the most common malignancy in women, with relatively little regional variation in risk, while the incidence of breast cancer is low. Other cancer sites showing moderately increased rates include the lip and oral cavity, particularly in females from the north and northeast, where the chewing of betel nut remains common among older generations, nasopharyngeal cancer, carcinoma of the esophagus in the southern region, and penile cancer, especially in the north and northeast. Previous studies which have investigated the etiological factors underlying these patterns are reviewed, and the implications for future research and for national cancer control policies are discussed. Introduction In Thailand, as in several other countries in Asia, rapid socioeconomic development and the control of noncommunicable disease have resulted in the emergence of cancer as the third most common cause of death after “heart disease” and accidents and poisoning (1). Although in the past some information on cancer patterns was available from hospital statistics, it was not Received I ))/ I 9/94: revised I /5/95; accepted I /6/95. I Financial support for this project was provided by the Cancer Research Foundation for the National Cancer Institute and the Oncological Society of Thailand. 2 To whom requests for reprints should be addressed. until 1986 that the first population-based cancer registry was founded at Chiang Mai, in the northern region (2). This was followed in 1988 by the registry in Khon Kaen in the northeast (3), and in 1990 in Songkhla in the south. In 1991, it was decided that these three registries would produce a combined analysis of their results, including estimates for the country as a whole. Because there was no registry present in the densely populated central region, a population-based cancer survey was planned and carried out in Bangkok in 1992, with the objective of collecting data on residents of the metropolitan area diagnosed with cancer between 1988 and 1990. This study is a summary of the full report on the project (4), which presents an overview of the cancer profile in the country as a whole, a comparison of regional differences, and a review of previous epidemiological studies. It thus provides a guide to future priorities for research into cancer cause and control. Materials and Methods Geography and Peoples The Thai people almost certainly originated in southern China and migrated southwards to occupy what is now modern Thailand, Laos, and eastern Myanmar up to the 13th century AD. This population is culturally and religiously (almost entirely Buddhist) quite homogeneous, with regional differences but variations in the basic pattern. Subsequent migrations brought large numbers of Chinese. These were estimated to be 2.5 million in 1958, but migration virtually ceased in 1948; individuals of Chinese origin have taken Thai names and are now assimilated to varying degrees, making up about 10-14% of the population. Most Thais of Chinese origin live in central Thailand (especially Bangkok) or other urban centers. About 10% of the population is comprised of other ethnic groups, including some 500,000 hill tribe peoples of northern Thailand, most originating in southern China and migrating in the last 200 years, and the peoples of the southernmost seven provinces, who are of Malay origin and predominantly Muslim in religion. Thailand is divided into 72 provinces grouped within 4 geographical regions: the northern, northeastern, southern, and central regions (Fig. 1). The northern region is mountainous with relatively cool winter temperatures and is the home of several minority tribes, some indigenous and others are more recent migrants. The northeast is a semi-arid plateau which, because it is the poorest part of the country, is attracting increasing industrial development. The population is culturally similar to that of neighboring Laos and speaks a distinct language (Isan) related to modern Lao. The central region is one of the most fertile rice-growing areas on earth and contains the densely populated Bangkok Metropolis (population, 5.8 million). The south is physically quite heterogeneous, with its long coastline and hilly interior given over to agriculture (fruit and rubber plantations), fishing, and tin mining. on August 27, 2017. © 1995 American Association for Cancer Research. cebp.aacrjournals.org Downloaded from