BRCA mutations up risk of non-breast cancers too

It's now well known that people who carry mutations in the BRCA 1 and 2 genes are prone to ovarian and breast cancer, but new findings show that these genes also increase risk of certain other cancers as well.

"However, the risks of cancer at sites other than the ovary and the breast are only moderate, and the major concerns in families eligible for BRCA1/2 mutation testing remain breast and ovarian cancer," Dr. Justo Lorenzo Bermejo told AMN Health.

Bermejo and Dr. Kari Hemminki from the German Cancer Research Center in Heidelberg conducted what is believed to be the largest population-based study on the risk of cancer at sites other than the breast in families with suspected BRCA1/2 mutations.

The team analyzed information on a total of 944,723 families in the Swedish Family-Cancer Database covering at least three generations.

In families with two cases of breast cancer occurring before age 50 - probably because of BRCA mutations - there is a moderately higher-than-normal risk of early pancreatic, prostate, and ovarian cancer, the investigators report in the Annals of Oncology.

The data also show an increased rate of eye cancer in families with ovarian and breast cancers, and increased risks of prostate and primary liver cancer in families with two breast cancer cases, at least one of them occurring before age 50.

Stomach cancer before age 70 was "twice as frequent" in ovarian and breast cancer families as in the general population, Bermejo and Hemminki report.

Summing up, the researchers say this study confirms "at a population level" the association of BRCA1/2 mutations with ovarian, pancreatic, prostate and stomach cancers.

However, the way early pancreatic cancer clustered in families with two breast cancers under age 50 years, as well as the pattern of occurrence of early prostate cancer, "seem to be due to other effects unrelated to BRCA1/2 mutations," they note.

This is "an important finding," Bermejo told Reuters Health, adding that studies are needed to pinpoint the additional factors that account for this increased risk.

SOURCE: Annals of Oncology, November 15, 2004.