Breast cancer in younger women in Switzerland 1996-2009: a longitudinal population-based study.

Background: Breast cancer (BC) is the most commonly diagnosed cancer and a leading cause of death in younger women.
Methods: We analysed incidence, mortality and relative survival (RS) in women with BC aged 20-49 years at diagnosis, between 1996 and 2009 in Switzerland. Trends are reported as estimated annual percentage changes (EAPC).
Results: Our findings confirm a slight increase in the incidence of BC in younger Swiss women during the period 1996-2009. The increase was largest in women aged 20-39 years (EAPC 1.8%). Mortality decreased in both age groups with similar EAPCs. Survival was lowest among women 20-39 years (10-year RS 73.4%). We observed no notable differences in stage of disease at diagnosis that might explain these differences.
Conclusions: The increased incidence and lower survival in younger women diagnosed with BC in Switzerland indicates possible differences in risk factors, tumour biology and treatment characteristics that require additional examination.
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