Cancer risks in women with 2 breast or ovarian cancers: clues to genetic cancer susceptibility.

Women diagnosed with 2 cancers of the breast and/or ovary are at higher risk of developing subsequent cancers. Using registrations from the Thames Cancer Registry, we quantified the risks at different cancer sites. Increased risks were found for cancers that are part of the BRCA1 and BRCA2 tumour spectrum: oropharyngeal cancer, malignant melanoma of the skin (BRCA2) and colon cancer (BRCA1). We also found significantly increased risks of myeloid leukaemia (probably due to radiotherapy) and of cancer of the corpus uteri (which may be due to hormonal factors).