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Risk Factors & Prevention
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Although it is not known exactly what causes ovarian cancer, certain traits make some women more likely than others to develop epithelial ovarian cancer. Each trait varies in significance for the individual.
The following risk factors may increase a woman's risk of developing ovarian cancer:
- the presence of a mutation in either the BRCA1, BRCA2, MLH1, MSH2, or MSH6 genes (see below for more information about Hereditary & Genetic Risk Factors)
- a first degree relative (mother, sister, or daughter) with ovarian cancer
- a personal history of breast cancer prior to age 40
- a personal history of breast cancer prior to age 50, and one or more close relatives with breast or ovarian cancer at any age
- two or more close relatives with breast cancer prior to age 50 or with ovarian cancer diagnosed at any age
- Ashkenazi Jewish heritage and a personal history of breast cancer prior to age 50
- Ashkenazi Jewish heritage and a first- or second-degree relative with breast cancer prior to age 50 or with ovarian cancer at any age
Lesser risk factors include any of the following:
- a history of infertility and/or use of assisted reproductive therapies, such as in vitro fertilization (IVF)
- a history of endometriosis (a condition in which tissue from the lining of the uterus grows outside of the uterus)
- a history of hormone replacement use for the management of symptoms related to menopause
- a personal history of breast cancer diagnosed after age 40 with no family history of breast or ovarian cancer
Hereditary & Genetic Risk Factors
The most important known risk factor is an inherited mutation of BRCA1 or BRCA2. Mutations in these genes are associated with up to 60 percent lifetime risk of ovarian cancer. A woman with one affected first-degree relative (mother, sister, or daughter) has a 5 percent lifetime risk of ovarian cancer. A woman with no affected relatives has a 1.4 percent lifetime risk of ovarian cancer.
The two genetic syndromes associated with an increased risk are hereditary breast-ovarian cancer (HBOC) syndrome and hereditary nonpolyposis colorectal cancer (HNPCC) syndrome. The breast-ovarian cancer syndrome occurs in families with inherited mutations in the BRCA1 or BRCA2 genes. The lifetime ovarian cancer risk for BRCA1 mutation carriers is 35 to 60 percent, and the risk for BRCA2 mutation carriers is between 10 to 27 percent. The HNPCC syndrome is associated with a 9 to 12 percent increased lifetime risk of ovarian cancer, and also a 40 to 60 percent lifetime risk of both uterine and colon cancer.
If a member of your family has had ovarian cancer at any age or breast cancer prior to age 50, you might want to consider having genetic counseling and possibly testing. Our Clinical Genetics Service offers counseling and testing to help you understand your risk and put together a plan, if necessary, to help you protect yourself. As part of Memorial Sloan-Kettering's goal to develop accurate methods to reduce risk of ovarian cancer, the Gynecologic Disease Management Team has introduced an extensive research program for women at high risk of developing ovarian cancer.
Risk-Reducing Salpingo-Oophorectomy
Memorial Sloan-Kettering researchers have established the value of risk-reducing, or "prophylactic," salpingo-oophorectomy -- removal of the ovaries and fallopian tubes before ovarian cancer has been diagnosed -- as a way to prevent breast and ovarian cancers in women who are at high risk of this disease because of mutations in the BRCA genes. Women who opt for this surgery will no longer be able to have children. Such therapy has been shown to decrease the risk of breast and ovarian cancers by 75 percent.1
Most salpingo-oophorectomy operations can be performed on an outpatient basis, using a minimally invasive procedure known as laparoscopy. During this procedure, a thin, tube-like instrument with a camera on its tip (a laparoscope) is inserted through the abdominal wall. Guided by the camera's highly magnified image, surgery is performed through surgical "ports" using tiny instruments.
One study has shown that the prophylactic removal of the ovaries and fallopian tubes may provide a different benefit for women who carry a genetic mutation in the BRCA2 gene than for those who have a BRCA1 genetic mutation. In the study, none of the women carrying the BRCA2 mutation who had the surgery developed ovarian cancer, while women carrying the BRCA1 mutation who had the surgery decreased their risk of developing ovarian or related cancers by 89 percent.2
This study also showed that women with BRCA2 mutations who chose prophylactic surgery also reduced their risk of developing breast cancer by 72 percent, while those with BRCA1 mutations reduced their risk of breast cancer by 45 percent. Additional research is underway to better understand why the results of the procedure differ in BRCA1 and BRCA2 carriers.
The decision to have a risk-reducing salpingo-oophorectomy is usually made after genetic counseling and possibly testing for mutations that may put a woman at risk for ovarian cancer. Because a woman cannot have children after this procedure, our investigators have initiated a study to learn more about the decision process leading up to surgery. Our researchers also want to find out more about the feelings associated with being at risk for ovarian cancer, and why or why not a woman opts for risk-reducing surgery.
Risk-Reducing Factors
The following factors have also been shown to decrease the risk of ovarian cancer by varying degrees:
- use of oral contraceptives for an extended period of time; when used for three years or longer, a woman's risk of developing ovarian cancer is decreased by 50 percent
- tubal ligation, or having one's tubes tied, appears to lower a woman's risk of ovarian cancer slightly; however, the surgery should not be done exclusively for this reason (it is most often performed to prevent pregnancy)
- hysterectomy (removal of the uterus); but as with tubal ligation, this surgery should not be done exclusively for this reason unless genetic abnormalities that increase the risk of ovarian cancer are present
- having one or more children, especially before age 30
- breast-feeding, especially for one year or more
1 N. D. Kauff, J. M. Satagopan, M. E. Robson, L. Scheuer, M. Hensley, C. A. Hudis, N. A. Ellis, J. Boyd, P. I. Borgen, R. R. Barakat, L. Norton, M. Castiel, K. Nafa, and K. Offit, Risk-reducing salpingo-oophorectomy in women with a BRCA1 or BRCA2 mutation, New England Journal of Medicine 346(21), 2002: 1609-15. [PubMed Abstract]
2 N. D. Kauff, S. M. Domchek, T. M. Friebel, J. B. Lee, R. Roth, M. E. Robson, R. R. Barakat, L. Norton, K. Offit, T. R. Rebbeck, and the PROSE Study Group, Multi-center prospective analysis of risk-reducing salpingo-oophorectomy to prevent BRCA-associated breast and ovarian cancer, Journal of Clinical Oncology, 2006 ASCO Annual Meeting Proceedings Part I. 24 (18S), 2006: 1003. [2006 ASCO abstract]
Last Updated: Jan. 2, 2008
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