Population-based cancer survival in Singapore, 1968 to 1992: An overview

Abstract

The Singapore Cancer Registry has provided comprehensive population-based incidence data since 1968. This paper describes the population-based survival analysis of the registry data. All invasive primary cancers diagnosed from January 1, 1968 to December 31, 1992 were passively followed up until December 31, 1997. Only 5.8% were lost to follow-up. Cumulative and observed survival rates were calculated using Hakulinen's method. Overall 5-year relative survival rates have increased dramatically over the 25-year period in both genders. Significant increases are seen with nasopharynx, stomach and colo-rectum cancers, non-Hodgkin's lymphoma, leukemias and cancers of the testis, cervix, ovaries and breast. When compared with the Surveillance, Epidemiology and End Results (SEER) rates in the United States, the 5-year relative survival rates in Singapore are generally lower. However, the rate of change between the two countries is fairly similar. On the average, the rates are 10 to 15 years behind the SEER rates and 5 to 10 years behind Finland, Switzerland and Japan, but they are close to the UK rates. Key words: relative survival; observed survival; developing countries; cancer registry; epidemiologyPopulation-based cancer survival data are useful in evaluating the effectiveness of the overall cancer control strategy in a region. For a small country like Singapore, population-based survival data will be especially useful for health planners and clinicians. Singapore has made rapid socio-economic progress since independence in 1963. The health services have also developed and expanded considerably with equitable access in the general population to a well-developed and modern health care infrastructure.The Singapore Cancer Registry has provided comprehensive population-based incidence data since 1968. 1 For the first time, a systematic study examining cancer survival for the period 1968 to 1992 was conducted in collaboration with the International Agency for Research on Cancer (IARC) of the World Health Organization. MATERIAL AND METHODSA total of 90,158 residents of Singapore were diagnosed with a single invasive primary cancer from January 1, 1968 to December 31, 1992. Of these, 4,845 (5.4%) were diagnosed on the basis of death certificates only (DCOs) and were excluded from analyses. A further 1,061 (1.2%) were autopsy cases, and these were also excluded from analysis. Follow-up was done passively until December 31, 1997 by matching with the death register. The vital status of the unmatched cases was assessed by matching with the electoral register of 1997; only 4,949 (5.8%) were lost to follow-up and excluded from survival analysis.The resident population for 1970 was 2,013,563; for 1980 it was 2,282,125 and for 1990 it was 2,705,115. These numbers were used to interpolate and extrapolate the population at risk by 5-year age groups and gender. 2 Cumulative observed and relative survival probabilities were calculated using Hakulinen's method. 3,4 Observed survival was based on deaths from all causes. Competing cause...

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