Long-term mortality of women with a diagnosis of breast cancer.

Survival from breast cancer has improved over the last few years, but scanty information is available on the long-term follow-up. We therefore considered data on 1,095 women with breast cancer diagnosed between 1974 and 1984 in the Swiss Cancer Registry of Vaud (population 616,000 inhabitants) who had survived for at least 10 years. Overall, 129 deaths from breast cancer were observed 10-19 years after the original diagnosis, corresponding to a standardized mortality ratio (SMR) of 20.3 (95% confidence interval (CI) 17.0-24.2). An excess mortality from breast cancer was observed 10-14 (SMR = 22.6) and 15-19 (SMR = 13.4) years after the original diagnosis. The SMR was 25.2 for women diagnosed with breast cancer at age <60 years. Consequently, total mortality was also elevated (SMR = 2.0, based on 294 deaths). None of the other causes of death was significantly elevated, but mortality from cardiovascular disease was 1.4 (95% CI 0.9-2.0) 15-19 years after breast cancer diagnosis. A second primary breast cancer was observed in 89 women. Of these, 19 (21%) died of breast cancer. Therefore in women diagnosed with breast cancer, there remains a substantial excess of breast cancer mortality up to 20 years after the original diagnosis.