Authors: Mirjam D K Alsaker Signe Opdahl Bjørn Olav Åsvold Pål R Romundstad Lars J Vatten
Publish Date: 2011/05/08
Volume: 130, Issue: 1, Pages: 175-182
Abstract
Reproductive factors that influence breast cancer risk may also have an impact on survival once the disease is diagnosed In this study 2640 women were diagnosed with invasive breast cancer during followup after a breast cancer screening that took place in 1956–1959 Survival was assessed in relation to age at menarche age at first birth parity history of breastfeeding age at menopause and the effect of BMI was assessed in a subset of patients It is a special feature that the patients of this study have not been subjected to organized mammography screening and their use of exogenous hormones has been negligible By the end of followup 2008 2301 87 of the patients had died and 1022 44 of the deaths were caused by breast cancer Breast cancer survival was not associated with age at menarche parity or time since last birth but survival was consistently poorer with increasing age at first birth P for trend 003 comparing a first birth after 35 years with 25–29 years the hazard ratio was 132 95 CI 102–172 There was no evidence for a doserelated effect of breastfeeding but BMI measured many years prior to diagnosis was inversely associated with survival P for trend 001 The main finding was that reproductive factors including breastfeeding appear to have little influence on the survival of breast cancer patients Age at first birth may be an exception to this since we found a gradually poorer survival with increasing age at first birth We also found that overweight and obesity as measured many years prior to diagnosis were associated with poorer survivalMDKA is a research fellow financed by the Norwegian University of Science and Technology NTNU The study was supported by a grant from the Norwegian Research Council We want to thank the Cancer Registry of Norway for providing the data the Norwegian Cancer Society for carrying out the original study and the attending women for participating in the study
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