Age as a prognostic factor in breast cancer.

Long-term survival was evaluated in a total of 12,319 women with first breast cancer, comprising 94.9% of virtually all women with first breast cancers diagnosed in Sweden in 1959 through 1963. After correction for the expected mortality, it was found that age at diagnosis was an important predictor of the probability of escaping the risk of dying of breast cancer (relative survival), with a regular trend toward a more favorable course in younger women. This difference between the age groups is apparent as early as 5 years after diagnosis and increases throughout the period of observation. Thus the relative 20-year survival rates +/- 95% confidence limits were 51.3 +/- 3.8%, 41.2 +/- 3.4%, 34.2 +/- 3.8%, and 16.6 +/- 6.3% at ages 40 through 44, 50 through 54, 60 through 69, and 70 through 79 years, respectively. Patients younger than 40 years diverged from the general trend, with a survival rate of 44.1 +/- 4.6% at 20 years.