A total of 52 cases of NPC were found in a five-year survey from 1978 to 1982 in Malaysia. The annual rate of occurrence was 3.4, 3.0, 2.4 and 1.8 for Chinese, Malays, Kadazans and Sarawakians, respectively. The age-specific incidence rates per 100 000 were highest for Kadazans (2.34 to 7.59) in comparison to the other races (0.11 to 1.24). The proportion of NPC in young Malaysians formed 1.2% in Chinese, 7.2% in Malays and 6.9% for others. A sexual bias was present in Chinese (male:female = 2.2) and Sarawakians (1.7) but not in Kadazans and Malays (0.9). In most Chinese, the primary tumour histologically is of the poorly differentiated characteristic and this type is the predominant tumour in the country. The Kadazans presented with well differentiated primary tumour and the Malays with all three histological types i.e. well-, poorly- and undifferentiated. At first examination enlarged lymph nodes were found in 95.7% of the patients and 65.2% had epistaxis and growth in the postnasal space. Antibodies to IgA anti-VCA were present in half of the 6 patients serologically studied.
A "registry" of all known cases of nasopharyngeal carcinoma in Malaysia, 1968-72, was established. Attention was focused on the State of Selangor where conditions are best for case finding. Age-adjusted incidence rates among Chinese males and females were 17·3 and 7·3 per 100,000; among Malay males and females, the rates were 2·5 and 0·3 and among Indian males, 1·1. The detailed ethnicity of 192 cases in Selangor was established. Estimated incidence rates for the Chinese sub-groups agreed with the pattern observed elsewhere: highest among the Cantonese, lowest among the Hokkien/Teochiu, with the Khek in between. There was no correlation between histological type and sub-ethnic group among the Chinese cases.
A record of all known cases of nasopharyngeal carcinoma in Malaysia is complete for 10 years from 1968 to 1977. Special efforts in case-finding were made in the State of Selangor where conditions are optimal. Age-adjusted incidence rates among Chinese males and females were 16.5 and 7.2 per 100,000, among Malay males and females 2.3 and 0.7 and among Indian males, 1.0. There were no significant changes in incidence rates over the 10-year period for sex and ethnic groups, or for Chinese subethnic groups. In Chinese subethnic groups, rates were highest among Cantonese, moderate among Khek and lowest among Hokkien and Teochiu. Standardized incidence ratios using Selangor as the standard population indicate considerable under-reporting in the less urban states of Malaysia, particularly among females. In Selangor, incidence rates were similar for urban and rural residents, but the frequency of cases was higher among Chinese working in industry and living in poor neighbourhoods.