ovarian cancer : BRCA1 and BRCA2 Mutations and Cancer Risk

Although the BRCA1 and BRCA2 genes appear to be similar in function, they are located on different chromosomes, and each, when mutated, confers varying degrees of risk, not only for inherited breast and ovarian cancer but for other types of cancer as well. The types of cancer associated with mutations in the BRCA1 and BRCA2 genes are as follows:

BRCA1. Mutations in the BRCA1 gene appear to increase an individual's risk for breast, ovarian, prostate, and possibly colon cancer.
BRCA2. Mutations in the BRCA2 gene appear to increase an individual's risk for breast (male and female), ovarian, prostate, and pancreatic cancers. In addition, researchers suspect that defects in this gene carry with them an increased risk for cancer of the lung, larynx (voice box), and skin; however, more studies are needed to confirm these associations.

Researchers are still trying to determine the exact risk of cancer that is conferred by carrying a mutation in the BRCA1 or BRCA2 gene.

Early studies indicated that 80 percent of women who had inherited mutations in either of these genes would one day develop breast cancer, and that 60 percent would eventually develop ovarian cancer. However, these numbers were based on data collected from women in high-risk families (that is, those in which several cases of cancer had already been diagnosed). As researchers have expanded their studies to include members of the general population, they are discovering that risk associated with having a mutation in BRCA1 or BRCA2 may actually be lower than initial studies indicated. For this reason, the degree of risk associated with these mutations is now most commonly expressed as a range of numbers rather than an absolute — at least until enough data exists to make better estimates.

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