The history of efforts to establish a cancer registry in Malaysia since 1961 is reviewed. In 1980, the staff of the Institute for Medical Research in Kuala Lumpur was authorized to develop an official registry that would combine the resources of the various university faculties, the hospitals, research institutes, and the Cancer Society. Special registries operate for oral precancerous conditions and for nasopharyngeal carcinoma (NPC). The topics of recent epidemiological studies include: a review of all cancers diagnosed at the University Hospital during 1972-74, the association of Epstein-Barr virus and NPC, social and environmental factors associated with NPC, oral cancers, and childhood cancers.
Data from 100 Chinese, 50 Malay, and 50 Indian adults resident in 1980 in the greater urban area of Kuala Lumpur, Malaysia, indicate a heavy use of cigarettes among males of all ethnic groups, light use among female Chinese, and none among female Malay and Indian. Consumption of other tobacco products was important only among Indian males; chewing betal quid among Indian males and also among Malay and Indian females. Alcohol use is increasing among both sexes and all ethnic groups, but Chinese and Indian groups use alcoholic drinks more frequently and in larger quantity than Malay. Beer and liquor are the most common drinks.
Malaysia and Hawaii have several advantages for epidemiologic and laboratory studies on nasopharyngeal carcinoma. Both have multiethnic populations with different incidence rates of nasopharyngeal carcinoma and different life-styles. Malaysia has large populations of Chinese, Malaya, and Indians, and the number of cases of nasopharyngeal carcinoma at any one time is comparatively large. Incidence rates for 1968--72, age-standardized to the World population, for Guangdong hua (Cantonese Chinese) in Malaysia were 24.3/100,000 for males and 12.0/100,000 for females. In Hawaii, the ratio was 12.9/100,000 for males and 6.7/100,000 for females. The small number of cases in Hawaii would require that research in that State be conducted in collaboration with research elsewhere with larger case numbers.
The evidence for a hypothesis that eating salted fish is associated with nasopharyngeal carcinoma (NPC) is reviewed. The hypothesis was tested among Malaysian Chinese using a matched case-control design. The kinds of salted fish and patterns of use were also investigated in a control group comprising 100 Chinese, 50 Malay and 50 Indian households. During 1980, in Selangor, Malaysia, interviews with 100 Chinese cases of NPC and 100 non-disease controls indicated that salted fish consumption during childhood was a significant risk (relative risk = 3.0, P = 0.04), with an elevated risk for daily as opposed to less frequent consumption. Salted fish consumption during adolescence was a less significant risk, and current consumption not at all. There were 19 kinds of fishes reported as being eaten as salted fish by the 200 control households. There were marked differences between ethnic groups in preference for different kinds: Chinese preferred red snapper (74% of households), Malay jewfish (54%) and Indian red snapper (28%). Salted fish was hardly ever eaten daily by any household; weekly was a moderate frequency in all ethnic groups; less than weekly most common. There were no statistically significant differences between Chinese NPC case and non-disease control participants in kind of salted fish eaten. Results were the same when the data were analyzed by sex, subethnic group and income.
No population-based cancer registry exists in Malaysia; thus our main sources of incidence data were biopsy series. We determined the frequency of cancers by body site, sex, and ethnic group from biopsy records of the Division of Pathology of the Institute for Medical Research in Kuala Lumpur for the years 1969-71. We then made comparisons of leading sites with data from the Singapore Cancer Registry. Relative risk values for 21 sites indicated significant differences among ethnic groups for cancers of the nasopharynx, larynx, lung, bone, skin, cervix, ovary, prostate, and penis and for lymphomas.
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.
With a five-year survival rate of 20% in 1970 and 40-45% in 1990, and highest incidence and mortality in early and middle adult years, nasopharyngeal carcinoma (NPC) may have a severe social impact on families and households. The aim of this study was to measure the social impact of NPC in the Chinese population of Selangor, Malaysia.
We conducted a case-control study of nasopharyngeal carcinoma among Malaysian Chinese to test inhalants, salted fish consumption, and use of tobacco, alcohol, and nasal ointments as risk factors for the disease. Interviews with 100 cases and 100 controls indicated that salted fish consumption during childhood was a significant risk factor (relative risk, 3.0; p = 0.04); childhood daily consumption of this food item compared to nonconsumption carried a relative risk of 17.4 [95% confidence interval = (2.7, 111.1)]. Occupational exposure to smokes (relative risk, 6.0; p = 0.006) and to dusts (relative risk, 4.0; p less than 0.001) was also significantly associated with nasopharyngeal carcinoma. The two risk factors (consumption of salted fish and exposure to smoke and/or dust) were independent of each other. There was no association between nasopharyngeal carcinoma and tobacco, alcohol, or nasal ointments.
We conducted 2 case-control studies with Malaysian and Hong Kong Chinese and investigated the association between salted fish intake and nasopharyngeal carcinoma (NPC). Both studies show a highly significant association between salted fish intake, especially during childhood, and NPC. Furthermore, from our results we estimate that the majority of NPC cases occurring in the southern Chinese can be attributed to their consumption of this food early in life.
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.
BACKGROUND: During 1990-1992, 282 Chinese residents of Selangor and the Federal Territory, Malaysia with histologically confirmed nasopharyngeal carcinoma (NPC) were interviewed about occupational history, diet, alcohol consumption, and tobacco use, as were an equal number of Malaysian Chinese population controls, pair-matched to cases by age and sex.
METHODS: Exposures to 20 kinds of workplace substances, solar and industrial heat, and cigarette smoke, were analysed by univariate and multivariate methods.
RESULTS: Nasopharyngeal carcinoma was associated with occupational exposures to construction, metal and wood dusts; motor fuel and oil; paints and varnishes; certain other chemicals; industrial heat; solar heat from outdoor occupations; certain smokes; cigarette smoking; and childhood exposure to parental smoking. After adjustment for risk from diet and cigarette smoke, only wood dust (OR = 2.36; 95% CI : 1.33- 4.19), and industrial heat (OR = 2.21; 95% CI : 1.12-4.33) remained clearly associated. Wood dust remained statistically significant after further adjustment for social class. No significant crude or adjusted association was found between NPC and formaldehyde (adjusted OR = 0.71; 95% CI : 0.34-1.43).
CONCLUSIONS: This study supports previous findings that some occupational inhalants are risk factors for NPC. The statistical effect of wood dust remained substantial after adjustment for diet, cigarette smoke, and social class. Intense industrial heat emerged as a previously unreported risk factor, statistically significant even after adjustment for diet and cigarette smoke. No association was found between NPC and formaldehyde.
We interviewed 282 histologically confirmed cases of nasopharyngeal carcinoma (NPC) in Chinese residents of Selangor and the Federal Territory, Malaysia, and an equal number of Chinese age-, sex-, and length-of-residence-matched controls sampled from the general population. Consumption of 55 dietary items during childhood, and 5 years pre-diagnosis of NPC, was analyzed by univariate and multivariate methods. Four salted preserved foods (fish, leafy vegetables, egg and root), fresh pork/beef organ meats and beer and liquor consumption exhibited strong positive associations, and 4 vegetable/fruit combinations strong negative associations with NPC. Factor analysis and multivariable modeling using estimated factor scores strongly supported separate effects on NPC of vegetables/fruits, salted preserved foods, pork/beef organ meats and beer/liquor consumption. Multivariable modeling associated NPC most clearly with high consumption of salted fish, salted eggs, pork/beef liver and beer and low consumption of Chinese flowering cabbage, oranges/tangerines and shrimp. A strong residual association of social class with NPC remained after adjustment for diet, which is consistent with a substantial role for non-dietary environmental factors.
The objective of this study was to establish baseline data about air pollutants potentially related to nasopharyngeal carcinoma (NPC) in the Federal Territory and Selangor, Malaysia. During 1991-1993, ambient air quality was monitored at 42 work sites representing ten industrial sectors: adhesive manufacturing, foundries, latex processing, metalworking, plywood/veneer milling, ricemilling, rubber tire manufacturing, sawmilling, shoemaking, and textile related industries. At each work site, aerosol particle size distributions and concentrations of formaldehyde, benzene, toluene, isopropyl alcohol, and furfural were measured. Mean aerosol particle concentrations ranged from 61 micrograms/m3 in foundries to 5,578 micrograms/m3 in ricemills, with five industries (adhesives, metalworking, ricemilling, sawmilling, and shoemaking) exceeding the US EPA 24-hr ambient air standard for PM-10. Formaldehyde concentrations exceeded the threshold limit value (TLV) in adhesives factories. Other vapours and elements measured were well below TLVs.