Gynecologic Cancer: What Every Woman Should Know
The Connection Between Breast and Ovarian Cancer
Updated on: June 20, 2003
Beth Y. Karlan, M.D., Director, Women’s Cancer Research Institute and Division of Gynecologic Oncology Cedars-Sinai Medical Center, Los Angeles, California
Do you have a personal or family history of breast cancer? If so, that puts you at higher than average risk for ovarian cancer.
All cancers are genetic, in the sense that cancers result from genes that go awry and cause the cells to grow unchecked. Only a minority of cancers, however, are hereditary, that is, they run in families and the cancer-causing genes are inherited from one or both parents.
Approximately 7-10 % of all ovarian and breast cancers are due to a genetic alteration that has been inherited from either the mother's or the father's side of the family. The genes responsible for the vast majority of hereditary breast and ovarian cases are called BRCA1 and BRCA2.
While all men and women have BRCA1 and BRCA2 genes, in some families a mistake or "mutation" in one of these genes may be passed down from generation to generation. In some populations, such as Jews from Eastern European backgrounds (called Ashkenazi Jews), mutations in BRCA1 and BRCA2 that occurred many generations ago have been widely dispersed, resulting in a higher percentage of people in this ethnic group carrying BRCA gene mutations. BRCA mutations, however, occur in women from many countries and cultures.
Female offspring who inherit a BRCA1 and/or BRCA2 gene mutation have an increased susceptibility to developing breast and ovarian cancer. In fact, women carrying these mutations have a lifetime risk of breast cancer between 60-85 %, and a 40-60 % risk of a second breast cancer after the first. That compares with the lifetime risk of just 8-11 % for in the general population. The breast cancers associated with BRCA mutations often occur at a much younger age than those occurring in the general population, frequently occurring before menopause or age 50.
The lifetime risk for ovarian cancer of BRCA1 mutation carriers is 15- 45 % and slightly lower, 15-30 %, for BRCA2 mutation carriers. This is in contrast to a 1.7% lifetime risk for women in the general population.
The ovarian cancers associated with these gene mutations, however, do not have any age predilection and may occur before or after a diagnosis of breast cancer in a given individual.
Even when breast cancer survivors are not BRCA1 or BRCA2 mutation carriers, their lifetime risk for ovarian cancer is three times that of the general population, 1 in 20 versus 1 in 55 women in the general population.
How Do You Know?
How do you determine if you or the women in your family are at elevated risk for breast or ovarian cancer?
Constructing your "pedigree" or cancer family tree is an important first step. Take the opportunity at your next family gathering to begin sleuthing out your family's cancer history.
Next, discuss your "pedigree" with your physician to decide whether or not you should be referred for genetic counseling and testing. Using about a tablespoon of your blood, genetic testing can determine whether there is an error or mutation in your BRCA1 or BRCA2 genes.
While the testing itself may cause minimal discomfort, the medical implications of the results may not be clear and may cause psychological stress. What's more, the testing may be costly, without assistance by your health insurance plan, and may have implications for your future insurability.
That's why genetic testing is generally recommended only for women with a higher than average likelihood of being BRCA1 or BRCA2 carriers. A woman with two or more family members who had breast cancer before the age of 50 or ovarian cancer fits this profile and should consider testing for the BRCA1 and BRCA2 gene mutations. Women diagnosed with breast cancer at an early age or with ovarian cancer at any age are also more likely to have mutations in these genes and are at higher risk for developing second breast or ovarian cancers. They, too, should consider BRCA testing.
Additional cancers in your family that may increase the chances of finding a mutation in one of these high-risk genes include breast cancer in a man, pancreatic cancer, stomach cancer, fallopian tube cancer, melanoma and sometimes prostate cancer.
Whether you undergo genetic testing and are found to carry a BRCA mutation or simply determine that you are at high risk for breast and ovarian cancer based on your family's cancer history, there are steps you may want to take in an attempt to reduce your risk. Some of the recommendations that have been put forth to reduce the risk of breast cancer include "chemoprevention" with tamoxifen, surgery such as "risk reduction" or prophylactic bilateral mastectomy, and increased surveillance with biannual mammogram and/or MRI.
For ovarian cancer, risk reduction strategies include chemoprevention with birth control pills, prophylactic bilateral oophorectomy (surgical removal of the ovaries), and increased surveillance with transvaginal ultrasound and CA125 testing.
Removal of the ovaries prior to menopause may also reduce your breast cancer risk.
Since none of these screening and prevention modalities are 100% effective, specific recommendations must be individualized and discussed at length with your physician.
Whenever possible, participation in clinical trials or high-risk clinics should be considered.
This article by the Gynecologic Cancer Foundation originally appeared in an advertising supplement to the New York Times on Sunday, June 22, 2003.
GCF gratefully acknowledges Aventis Oncology for its generous support of this educational supplement. The content of this supplement is the work of many individuals and does not reflect commercial interests.
Aventis Pharmaceuticals
www.AventisOncology.com