Do younger female breast cancer patients have a poorer prognosis? Results from a population-based survival analysis

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 a 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. (C) 2003 Wiley-Liss, Inc.