N Martin

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.

There are five population-based cancer registries in Thailand in different regions of the country. Four of them (Chiang Mai, Khon Kaen, Bangkok, and Songkhla) have been operating since 1988 and the other (Lampang) since the early 1990s. These registries have published regular 3-year cancer incidence reports since the first in 1993 for the period 1989-1991. The objective of this article is to summarize the figures of cancer incidence in Thailand during 1995-1997. The population of Thailand in 1996, at the middle of the period, was 27 million males and 27.5 million females. Information of cancer cases residing in the five provinces was collected and abstracted from different sources. Age-standardized incidence rate (ASR) of cancer in males and females was calculated for each registry and that for the whole country was estimated using the five registries as representatives for the four geographical regions of Thailand. The estimated number of new cancer cases in 1996 for the whole country was 35,539 men and 38,476 women and the ASRs were 149.2 and 125.0 per 10(5) population in men and women respectively. Cancer incidences greatly differed from region to region. Lung cancer was the commonest in Chiang Mai and Lampang in the Northern region in both sexes. The incidence of liver cancer in Khon Kaen in the Northeastern region outnumbered all the others in both sexes; cholangiocarcinoma was the major type of liver cancer. In Bangkok, lung cancer was the most important cancer in males and breast cancer was in females. Though it was lung and cervix uteri cancer that ranked the first in men and women in Songkhla, the rate of oral and pharyngeal cancer was exceptionally higher than in other registries. The geographical variability in cancer patterns in Thailand reflects exposure of the population to different risk factors unique to the different regions. In the study as a whole, there are some methodological weak points in estimating the ASRs and number of cancer cases for the whole country, but the results are the most reliable cancer statistics from Thailand at the moment. In conclusion, both a country-wide and region-specific cancer control programmes are needed for Thailand. The national one would be for the cancers common to all regions, and the provincial-level emphasis should be on cancers which are the major problems in the area.

Incidence rates of cancers of childhood in Thailand are presented for the first time, and compared with results from cancer registries in Asia, Europe and the USA. As elsewhere in the world, leukaemia (principally acute lymphocytic), brain tumours and lymphomas comprise two-thirds of all childhood neoplasms. Carcinomas are rare, but the principal sites (liver, nasopharynx, thyroid and salivary gland) are extremely unusual elsewhere. Several features of the cancer pattern correspond to that in other Asian populations (China, Japan, Philippines), in particular the low incidence of Hodgkin's disease, Wilms' tumour and Ewing's sarcoma. Conversely, Burkitt's lymphoma is more common than elsewhere, although this may represent increasing awareness of this diagnosis amongst clinicians in recent years.