Younger women who develop breast cancer are hypothesized to have poorer survival rates than women who develop it at a later stage in life. Several studies have suggested that differences in biologic characteristics of breast cancer in younger (premenopausal) and older (postmenopausal) women may account for the prognostic variation. This population-based cohort study reports on survival rates of breast cancer in Singapore and examines the hypothesis that younger breast cancer patients have a poorer prognosis. A total of 6,397 breast cancer patients diagnosed from 1968 to 1992 were identified from the population-based cancer registry and followed up through 1997. Outcome measures were relative survival rates (RSRs) calculated using Hakulinen's method and excess hazards ratios (HRs) derived from a regression model based on relative survival. The 2-, 5-and 10-year RSRs were worse among those aged > 75 (65%, 48% and 39%, respectively). The best survival rates were seen among those aged 40 -44 (84%, 67% and 56%). Patients younger than 35 years faired reasonably well (79%, 60% and 50%). When the data were stratified according to clinical stage and calendar year, the highest risk of excess deaths was found in women > 75 years old. In patients with localized cancer and/or regional metastases, those in the 35-39 age group had the lowest excess risk. In patients with distant metastases, those younger than 35 years of age had the lowest excess risk of death. At the population level, younger women (< 45 years) with breast cancer in Singapore have higher relative survival rates. © 2003 Wiley-Liss, Inc. Key words: breast cancer; cancer registry; epidemiology, record linkageYounger women who develop breast cancer are hypothesized to have more biologically aggressive cancer and hence poorer survival rates. [1][2][3][4][5][6][7][8][9][10][11] This traditionally held view is of great concern, especially in populations with relatively higher incidences of breast cancer in younger females. In Singapore, for example, the peak age-specific incidence is in the 45-to 49-year age group, 12,13 whereas in the Western Caucasian populations, the peak is in the postmenopausal age groups. 14,15 Breast cancer among younger premenopausal women has higher rates of proliferation, lymphovascular invasion and lower levels of estrogen/progesterone receptors than older patients with cancer of the same stage. Among Caucasian females with lymph nodenegative breast cancer, those who are negative for estrogen (ERϪ) and progesterone receptors (PRϪ) appear to have the worst prognosis, earliest age of onset and worst grade. 2,3,[5][6][7][8][9]16 In the large U.S. study on ER and PR status based on the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) cancer registries, ERϪ/PRϪ cancers have a single peak at a younger age as well as higher proportion of advanced-stage cancer. 17 These differences in biologic characteristics could account for the poorer prognosis in the younger patients. It has also been suggested that young age serv...

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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