Studies have shown that a number of factors can increase or decrease ovarian cancer risk. Women who have never had children, have never breast fed and those with endometriosis have an increased risk. Women who have used oral contraceptive pills or have had a tubal ligation are at decreased risk. However, any combination of these factors can only change a woman’s risk of ovarian cancer from a baseline of approximately 1.5% to somewhere between 1% and 5%. At these levels of risk, neither screening with ultrasound or CA125 nor preventive surgery is recommended.
In contrast, some families carry inherited mutations (changes) in genes that dramatically increase the risk of ovarian, tubal, and peritoneal cancers. The most common of these are in the BRCA1 and BRCA2 genes. For women with a mutation in one of these genes, the lifetime risk of having ovarian, tubal or peritoneal cancer is 39-46% in BRCA1 mutation carriers and 12-20% in BRCA2 mutation carriers. Mutations in these genes also markedly increase breast cancer risk, raising a woman’s lifetime risk of breast cancer to 65-74% compared to 12% in the general population. BRCA1 and BRCA2 associated breast cancers often occur at much earlier ages than non-inherited breast cancers. While it is common to find multiple women affected with cancer in these families, approximately one-third of women with a BRCA1 or BRCA2 mutation who are diagnosed with breast or ovarian cancer have no known family members with breast or ovarian cancer.
For women with mutations in BRCA1 and BRCA2, there are proven methods to reduce the risk of ovarian and breast cancer. Genetic counseling (sometimes with genetic testing) is generally the best way to determine if you may be at risk of hereditary breast or ovarian cancer. If you have a personal or family history of any of the following, speak to your doctor about referral for genetic risk assessment.
- You had breast cancer before age 45 or ovarian cancer at any age.
- You had breast cancer before age 50 and have at least one close blood relation (i.e. parent, child, sibling, grandparent, grandchild, aunt, uncle, niece or nephew), on either your mother’s or father’s side of the family, who has had breast cancer prior to age 50, ovarian cancer at any age, or male breast cancer at any age.
- You have a close blood relation, on either your mother’s or father’s side of the family, who has had ovarian cancer at any age.
- You have two or more close relatives on the same side of the family (either your mother’s or father’s) that have had breast cancer before age 50.
- You are of Eastern European (Ashkenazi) Jewish ancestry and you or a close relative, on either side of your family, has had breast cancer before age 50, ovarian cancer at any age, or male breast cancer at any age.
Preventive surgery to remove the ovaries and fallopian tubes (after childbearing is complete) is the most effective method for preventing ovarian cancer in women with BRCA1 or BRCA2 mutations.
Annual breast MRIs in addition to annual mammograms are also recommended starting no later than age 30 to reduce the risk of breast cancer mortality through early detection. Removal of the ovaries and fallopian tubes can reduce the risk of breast cancer in women with BRCA1 and BRCA2 mutations by 40–70% if done prior to menopause.
Although not of proven benefit, for women with BRCA1 or BRCA2 mutations, screening for ovarian cancer with the CA125 blood test and transvaginal ultrasound is advocated by many experts during the reproductive years prior to preventive surgery. Use of oral contraceptives, which reduce the risk of ovarian cancer, can also be considered.
- Buys SS, Partridge E, Black A, Johnson CC, Lamerato L, Isaacs C, et al. Effect of screening on ovarian cancer mortality: the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Randomized Controlled Trial. JAMA. 2011;305:2295-303.
- Lancaster JM, Powell CB, Kauff ND, Cass I, Chen LM, Lu KH, Mutch DG, Berchuck A, Karlan BY, Herzog TJ for the Society of Gynecologic Oncologists Education Committee Statement on Risk Assessment for Inherited Gynecologic Cancer Predispositions. Gynecol Oncol 2007;107:159-62.
- Lu K, Kauff N, Powell CB, Chen LM, Cass I, Lancaster JM, Karlan B, Berchuck A, Mutch D. Hereditary Breast and Ovarian Cancer Syndrome. ACOG PRACTICE BULLETIN, Gynecol Oncol 2009;113:6-11 and Obstet Gynecol. 2009;113:957-66.
- Berek JS, Chalas E, Edelson M, Moore DH, Burke WM, Cliby WA, Berchuck A. for the Society of Gynecologic Oncologists Clinical Practice Committee. Prophylactic and risk-reducing bilateral salpingo-oophorectomy: Recommendations based on risk of ovarian cancer. Obstet Gynecol. 2010;116:733-43.
- National Comprehensive Cancer Network: NCCN Clinical Practice Guidelines in Oncology – Genetic/Familial High-Risk Assessment: Breast and Ovarian. Version 1.2012. http://www.nccn.org. 2012.
- Foundation for Women’s Cancer – November 26, 2012
- Society of Gynecologic Oncology – November 26, 2012
- CONVERSATIONS! – November 27, 2013
- Ovarian Cancer National Alliance – November 27, 2012
- Ovarian Cancer Research Fund – November 27, 2012
- Childhood Gynecologic Cancer Association – November 30, 2012
- National Ovarian Cancer Coalition – December 17, 2012
- SHARE: Self-help for Women with Breast or Ovarian Cancer – December 18, 2012
- FORCE Facing Our Risk of Cancer Empowered – January 3, 2013
- CCare Lynch Syndrome – January 29, 2013
- Ovarian Cancer Canada – February 11, 2013
- Society for Women’s Health Research – February 26, 2013
- National Cervical Cancer Coalition – May 1, 2013
- American Sexual Health Association - May 1, 2013