Effect of age at diagnosis of breast cancer on the patterns and risk of mortality from all causes: a population-based study in Australia.

AIMS This retrospective, population-based study investigated the patterns and risks of mortality from breast cancer, other cancers and non-cancer causes according to the age at diagnosis of breast cancer. METHODS Mortality was assessed in all Australian women (n = 179,653) aged 30-79 years who were diagnosed with breast cancer between 1982 and 2004 and who survived a minimum of 1 year. The mean follow up was 6.3 years (range 0-23 years). RESULTS Before December 2005, 52,934 women had died (34,459 of breast cancer, 5019 of other cancers and 13,456 of non-cancer causes). There was an inverse age-related relative risk of mortality (calculated as the standardized mortality ratio [SMR]) from breast cancer (linear trend across age P < 0.01). For breast cancer survivors the age-adjusted SMR was 0.99 for other cancers and 0.81(P < 0.01) for non-cancer causes in comparison with the general population. The SMR for other cancers and non-cancer causes was highest in the 30-39-year-old age group (2.13, P < 0.01 and 2.15, P < 0.01, respectively), and progressively decreased with increasing age, with the 70-79-year-old age group having significantly reduced SMR (0.95, P < 0.05, and 0.78, P < 0.01, respectively, compared with the age-matched general population). CONCLUSION There was an inverse age-related relative risk of death from breast cancer, other cancers and non-cancer causes. These findings suggest that younger Australian women require long-term health surveillance and that older women with limited comorbidities require optimal treatment of their breast cancer.