Heredity & Genetics
Ovarian cancer is due to a combination of genetic (inherited) and environmental (non-inherited) factors. The risk of developing ovarian cancer is higher among women who have a close relative with ovarian cancer.
In the general population of the United States, the chance of a woman developing ovarian cancer during her lifetime is about 1.8 percent. Among women whose mother or sister had ovarian cancer, the chance rises to 4 to 7 percent.
Although many women have a family history of ovarian or breast cancer, only about 10 to 15 percent of ovarian cancers are the result of inherited cancer susceptibility genes. Clues in the family history that are suggestive of a hereditary susceptibility include:
- Two or more relatives with ovarian or breast cancer, especially if the diagnoses occurred before menopause
- Women who have had both breast and ovarian cancer
- Women who have had breast cancer in both breasts
- Men who have had breast cancer
- Two or more relatives with colon or uterine cancer, especially if the diagnoses occurred at younger ages
To date, BRCA 1 and BRCA 2 are the two main breast and ovarian cancer susceptibility genes that have been identified. If a woman inherits an alternation or "mutation" in a BRCA 1 or BRCA 2 gene from either of her parents, her chances of developing ovarian cancer and breast cancer are significantly higher than average.
In the general population, BRCA 1 and BRCA 2 mutations are uncommon; however, they are found more frequently in families with strong histories of cancer, as described above. Specific mutations in the BRCA 1 and BRCA 2 genes are found more often among families of particular ethnic backgrounds.
For example, approximately 1 in 40 Ashkenazi (Eastern European) Jewish individuals carry BRCA 1 or BRCA 2 mutations. Among Ashkenazi Jewish women who have had breast cancer at a young age or ovarian cancer, the chance is even higher. Different BRCA 1 and BRCA 2 mutations have been found that are more common in other groups, including the Dutch, Icelandic and Swedish populations.
Genetic Counseling & Risk Assessment
Participants in the NOCEDPP clinical program receive a consultation with a genetic counselor during their first visit. The genetic counselor asks detailed questions about the family history of cancer and constructs a family tree. The family tree is useful in assessing the pattern of cancers in the family and estimating the likelihood of a hereditary susceptibility.
In order for the family history evaluation to be as accurate as possible, participants are encouraged to gather as much information as they can about their family history of cancer before their first visit. Upon review of the family history, each participant will be given an estimate of her risk for ovarian cancer. Women who have family histories that are suggestive of a hereditary susceptibility have the option to learn more about genetic testing for hereditary ovarian cancer.
Participants will talk with a genetic counselor about the potential benefits and limitations of genetic testing. They will also discuss:
- The meaning of positive and negative results
- Options for cancer surveillance and prevention available to women who test positive
- Implications for family members
- Psychosocial issues that may arise during and after the genetic testing process.
Whether or not to have genetic testing is ultimately up to the individual, and it is not required for participation in the NOCEDPP. Genetic testing often involves additional charges that will be explained in detail during the genetic counseling appointment.
The blood that may be drawn for genetic testing should not be confused with the blood that will be drawn from study participants for experimental purposes.
To learn more about NOCEDPP or to find out if you qualify for the program, please call 312-695-1651.
If you need more information about ovarian cancer or other ovarian abnormalities or would like to make an appointment with a Northwestern Memorial Hospital gynecologist for the first time, call our Physician Referral Department at 1-877-926-4664 or request an appointment online.
The ovarian cancer section was made possible by a generous grant from Bears Care.