Menarche, menopause, and breast cancer risk: individual participant meta-analysis, including 118 964 women with breast cancer from 117 epidemiological studies.

ABSTRACT:

Background

Menarche and menopause mark the onset and cessation, respectively, of ovarian activity associated with reproduction, and affect breast cancer risk. Our aim was to assess the strengths of their effects and determine whether they depend on characteristics of the tumours or the affected women.

Methods

Individual data from 117 epidemiological studies, including 118 964 women with invasive breast cancer and 306 091 without the disease, none of whom had used menopausal hormone therapy, were included in the analyses. We calculated adjusted relative risks (RRs) associated with menarche and menopause for breast cancer overall, and by tumour histology and by oestrogen receptor expression.

Findings

Breast cancer risk increased by a factor of 1·050 (95% CI 1·044-1·057;

SUBMITTER: Collaborative Group on Hormonal Factors in Breast Cancer 

PROVIDER: S-EPMC3488186 | biostudies-literature | 2012 Nov

REPOSITORIES: biostudies-literature