Association of time since last birth, age at first birth and parity with breast cancer survival among parous women; a register- based study from Norway
International Journal of Cancer, 05/07/2012
Alsaker MDK et al. – Reproductive factors were associated with survival from breast cancer diagnosed before, but not after age 50 years. Young women had a particularly poor prognosis throughout the study period.
We combined information from two population based registries and obtained information on 16 970 parous women with invasive breast cancer.
Cox regression analysis was used to assess breast cancer survival in relation to age at diagnosis, age at first birth, time since last birth and parity.
We stratified the analyses by age at diagnosis (<50 and >/= 50 years) as an approximation for menopausal age.
In women diagnosed before 50 years of age, breast cancer survival was reduced with younger age at diagnosis (p for trend <0.001), whereas in women diagnosed at 50 years or later, survival was reduced with older age at diagnosis (p for trend 0.011).
For breast cancer diagnosed before 50 years, survival was poorer in women with four or more births compared to women with one or two births (HR 1.3, 95 % CI 1.1-1.6).
A short time since last birth was associated with reduced survival (p for trend 0.05), but adjustment for stage and grade attenuated the association.
Among women diagnosed at 50 years or later, we found no association with survival for any of the reproductive factors.
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