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Thursday, July 24, 2014
I am a carrier of the BRCA2 gene. What types of cancer am I at a higher risk for, besides breast and ovarian?
Other cancers that have been reported in families with BRCA2 mutations include melanoma of the skin and melanoma of the eye, pancreatic cancer, and stomach cancer. Cancers of the larynx, esophagus, gallbladder, bile duct, and leukemias and lymphomas have also been reported.
There are few good estimates for how likely a woman or man will develop one of these other cancers, however the chance is low. The risk for women with BRCA2 mutations to develop pancreatic cancer is reported to be 1-2% and the risk for men with BRCA2 mutations is up to 4%.
In some of the early reports on families with BRCA2 mutations, it was thought that colon cancer risk might also be more common in BRCA2 families, but this hasn't been seen in subsequent studies. Men with BRCA2 mutations are also at somewhat increased risk for prostate cancer, especially prior to age 60, and male breast cancer. It seems that there may be other genes that influence whether BRCA2 carriers develop the rarer cancers; there seem to be particular families where pancreatic cancer or stomach cancer are more common.
At this time, some medical groups recommend pancreatic cancer screening for people with BRCA2 mutations, but there is no data proving pancreatic screening to be effective in increasing survival. For families with an unusually high numbers of rarer cancers, screening recommendations may be altered to reflect the cancers in these families.
For a bit of background for other readers, the BRCA2 gene is one of two somewhat common genes that cause a substantially increased risk for breast and ovarian cancer in women. Mutations in these genes are found in about 1 out 300 to 1 out of 500 individuals of European ancestry. They are more common in individuals of Ashkenazi Jewish ancestry (about 1 out of 40 individuals), but there are reports of people of all nationalities and ethnic backgrounds with BRCA1 and BRCA2 mutations.
Mutations in these genes increase a woman's risk for breast cancer from a population average of about 12% lifetime risk to 50-85% lifetime risk. The average woman has a 1-2% lifetime risk for ovarian cancer, while woman with BRCA1 and BRCA2 mutations have on the order of 14-45% lifetime risk for ovarian cancer.
Duane D Culler, PhD, MS
Clinical Instructor of Genetics
School of Medicine
Case Western Reserve University