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Genetic Testing for Breast & Ovarian Cancer

When the family history is positive for breast and/or ovarian cancer, DNA testing for a mutation in the BRCA1 and BRCA2 genes may be appropriate.

Women who carry one of the BRCA1 mutations have the following lifetime risks:

• Ovarian cancer: 15-45%
• Breast cancer: 50-85%
• Second primary breast cancer: 40-60%

When an individual carries a BRCA2 mutation the lifetime risks are:

• Ovarian cancer: 10-30%
• Breast cancer: 50-85%
• Male breast cancer: 6%

Other cancers such as primary peritoneal and fallopian tube are increased as well. One study showed that prophylactic bilateral oophorectomy reduced the risk of BRCA related gynecological cancers by 96% and decreased the risk of breast cancer by 53%. Another study found that gynecological cancers were reduced by 85% and breast cancer was reduced by 68%. It was also found that when the ovaries were removed prophylactically, in some cases early stage ovarian cancer was present, although not suspected despite careful surveillance. For this reason, it is recommended that oophorectomy be performed as soon as child bearing is completed.

Ovarian, Colon & Endometrial Cancers In Hereditary Nonpolyposis Colorectal Cancer (Hnpcc)

If the family history reveals a pattern of ovarian cancer, colorectal cancer and endometrial cancer in the same individual or close relatives, the family may be carrying a mutation which predisposes individuals to HNPCC. Genetic testing is available for the most common mutations, MLH1 and MSH2. A small number of cases may be caused by other genes that have been identified, including MSH6, PMS1 and PMS2. If a person carries the MSH2 or MLH1 mutation, the risk of colorectal cancer is estimated to be 70-82% by age 70. When a mutation is present, there is an increased risk for cancer at a number of other sites, including the ovary.

There are a number of other adult cancer syndromes which have a genetic basis. For more information on these rare syndromes, see Olopade and Pichert’s review.

The Genetic Testing Protocol

Currently genetic testing for BRCA mutations is offered when the risk is estimated to be 10% or greater. Some individuals may benefit from testing even if the calculated risk is lower. It is always preferable to test an affected relative first, because if the relative with cancer does not carry the BRCA mutation, then testing other family members will be uninformative and a negative result could give false reassurance of lower risk. Other genes will be identified eventually for the familial cases that are BRCA negative.

Prior to presymptomatic testing, thorough genetic education and counseling is necessary. The patient should be made aware of the risks, benefits and limitations of testing. There is a real possibility that the test may identify a genetic alteration of unknown significance. In addition to presenting the factual information, time must be spent exploring the emotional side of testing, exploring the concerns, fears and motivation for testing. If he or she decides to proceed with testing, results should always be given in person, with a support person accompanying the person who has been tested. Getting these results will be a very emotional experience, even when the result is negative and the mutation is not present. If the result is positive, consultation with an oncologist is recommended to review treatment options. Support from the health care team, family and friends is crucial.

It is also necessary to explain to patients the meaning of a positive, negative or uncertain result. For example, a negative result (no mutation identified) is much more meaningful for a relative of someone with a known mutation. If none of the affected relatives has been tested, then a different or unknown mutation may be present in that family. Women who test negative for a mutation will still have the same risk as the general population to develop cancer.

Cost for Counseling & Testing

Some insurance companies cover the costs of genetic counseling/testing and some do not. Because the use of genetic counseling has the potential to benefit the entire family, especially if a gene mutation is found, some families may be motivated to secure funds on their own to pay for the costs of these services.