No abstract

Introduction Phytoestrogens are a group of compounds found in plants that structurally resemble the hormone oestradiol, and thus have the potential to act as oestrogen agonists or antagonists. Their potential effects may alter the risk of breast cancer, but only a limited range of phytoestrogens has been examined in prospective cohort studies.

Germline loss-of-function mutations in BRCA1 are associated with a high lifetime risk of breast and ovarian cancer. Most mutations in the gene are 'truncating': in the main these induce premature termination codons, resulting in nonsense-mediated decay, loss of the transcript and/or the entire protein. The improved screening methods now in use across the UK will identify many carriers of unclassified BRCA1 variants. These are chiefly missense mutations, introducing an amino acid change in the context of an expressed protein. Indeed more than one-quarter of entries recorded in the Breast Cancer Information Core dataset of BRCA1 sequence variants collected from patients worldwide are unclassified missense alterations (http://research.nhgri.nih.gov/bic/). Currently, discovery of the majority of missense variants leaves both variant carriers and their families in an ambiguous position.