Breast Cancer Genes Linked to Other Cancers
Researchers Find Moderate Rise in Risk for Pancreatic, Prostate, Stomach Cancers
Nov. 16, 2004 -- Family members of those who carry the inherited genetic mutations BRCA1 and BRCA2, which are involved in hereditary breast and ovarian cancer, are at moderate risk for developing other types of cancer, scientists in Sweden report.
The largest population study ever conducted regarding BRCA1 and BRCA2 mutations has revealed that people with these mutations may also have an increased risk of pancreatic, prostate, and stomach cancers.
Testing for the BRCA mutation is recommended only for families with a strong history of breast cancer. Adults may be eligible for such testing if they have a personal or significant family history of breast cancer.
The BRCA1 and BRCA2 genes make proteins that keep cells from growing abnormally. According to the National Cancer Institute, a woman who inherits a mutation in her BRCA1 or BRCA2 gene is three to seven times more likely to develop breast cancer than one who does not. These mutations also increase the risk of ovarian cancer.
But until now, there have been no long-term studies of the rate of cancers in families who have a BRCA1 or BRCA2 mutation compared with the rates of cancers in the general population.
Researchers Justo Lorenzon Bermejo, MD, and Kari Hemminski compared the rate of cancers between genetic testing-eligible patients and the Swedish population.
Their study, which evaluated data from 10.2 million people, concluded that families with hereditary breast and ovarian cancers have higher rates of pancreatic, prostate, and stomach cancers.
They found that family members with two or more cases of breast cancer before the age of 50 (a criteria for BRCA testing) showed significant increases in risks for ovarian and prostate cancer, as well as an increase in pancreatic cancer before the age of 50.
But most ovarian cancers in these family members were not due to the BRCA1 or BRCA2 mutation, the researchers found.
They found that stomach cancer before the age of 70 was twice as frequent in families with breast and ovarian cancer as in the general population.
"The main message from our study for families which fulfill the criteria for mutation testing is that their risk for cancers other than breast and ovarian cancer is only moderate. The message for those involved in clinical counseling is that most ovarian cancers in families eligible for mutation testing are not related to BRCA1/2 mutations."
The findings are published in the latest issue of the Annals of Oncology.