BACKGROUND: Non-Hodgkin's lymphoma has increased in incidence in many countries, particularly in the West. Advances in diagnostic methods and the understanding of the disease over time pose a challenge to the interpretation of these trends. The aim of this study was to determine if the disease has increased in Singapore, a newly industrialized Asian country, and to examine the possible factors that may account for any observed changes.
METHODS: Data from the population-based Singapore Cancer Registry for the period 1968 to 1992 were reviewed to determine time trends based on sex and ethnic group. The Poisson regression model was fitted to the cross-tabulated data to obtain the adjusted incidence density ratios.
RESULTS: A total of 1988 cases of non-Hodgkin's lymphoma were included in the analysis. There was an overall increase in incidence among both Chinese and Malaysians. However, the rate of increase was greater in females (age-standardized rate from 1.8 per 100,000 in 1968-1972 to 4.5 per 100,000 in 1988-1992) than in males (3.2 per 100,000 to 5.9 per 100,000 in the same time periods). Between ethnic groups, Malay females were at higher overall risk compared with their Chinese counterparts (incidence density ratio 1.32; 95% confidence interval, 1.08-1.61). Although a substantial proportion of patients diagnosed with Hodgkin's disease between 1968 and 1972 were reclassified on review, using present criteria, as having non-Hodgkin's lymphoma, it is unlikely that this, and other recent changes in histologic interpretation, could have accounted for an increase of this magnitude.
CONCLUSIONS: Non-Hodgkin's lymphoma has increased in incidence among the Chinese and Malay populations in Singapore. The pattern of increase differs from that of the common cancer sites, and suggests the need to look for environmental and genetic factors that have not yet been elucidated.
The close epidemiological relationships between specific genital human papillomavirus (HPV) types and neoplasia of the cervix uteri have been extensively documented worldwide, including Singapore. Cervical cancer incidence rates in Singapore show variations between the major ethnic groups. To ascertain the corresponding HPV infection rates among the various races in Singapore, we analysed the cervical smears of 225 women by filter in situ DNA hybridization, and compared the data with a previous similar study. Fourteen (6.2%) individuals were HPV-positive, with HPV 16 and HPV 31 being the commonest types. No significant difference between HPV positivity rates in Chinese (5.0%) and in Malays (6.7%) was found, even though Chinese have a higher cervical cancer incidence than Malays. Furthermore, the cervical HPV carriage rate among women with normal cytology was 5.9%. In the light of reports of high genital HPV prevalence rates detected by DNA amplification, these data support the notion that HPV infection is commonly latent and requires the cooperation of other factors for cervical carcinogenesis.