Ovarian cancer is the ninth most common cancer in women, but is the fifth most common cause of cancer deaths in women in the United States. It is the most common cause of gynecologic cancer death. The American Cancer Society estimates that about 21,880 women will be diagnosed with ovarian cancer in 2011, and over 13,850 women will die of ovarian cancer this year. The lifetime risk of developing ovarian cancer is 1 in 70 for women at average risk. The average age at diagnosis is 63. Caucasian women have the highest incidence. Most women (about 70%) are diagnosed with advanced stage ovarian cancer (stage 3 or 4). When ovarian cancer is found early (stage I), the five-year survival is greater than 90%.
There are three main types of ovarian cancer: epithelial, germ cell, and sex-cord stromal tumors. Epithelial ovarian cancer is the most common, accounting for about 90% of all ovarian cancer. In this article, I will focus on epithelial ovarian cancer.
Risk Factors and Genetic Predisposition
Risk factors for ovarian cancer include early age at menarche (when menses start, before age 12), late menopause (after age 50), never being pregnant, infertility, endometriosis and polycystic ovarian syndrome. Family history of breast or ovarian cancer is also a risk, and about 10% of all ovarian cancer is hereditary.
There are two main inherited genetic predispositions for ovarian cancer: a BRCA 1 or 2 mutation and hereditary nonpolyposis colorectal cancer (HNPCC). Women with a BRCA 1 mutation have a 20 to 45% lifetime chance of developing ovarian cancer, while women with a BRCA2 mutation have a 10 to 20% lifetime chance. Women with a BRCA mutation are also at increased risk of developing breast cancer. Women with HNPCC have a 9 to 12% lifetime risk of developing ovarian cancer. Other cancers associated with HNPCC include colon cancer, uterine cancer, stomach cancer, small bowel cancer and kidney cancer. Any woman diagnosed with ovarian cancer should consider seeing a genetics counselor for BRCA testing.
A woman can reduce her risk of ovarian cancer in several ways. Taking birth control pills for five years can reduce a woman’s risk of ovarian cancer by 50%. Breastfeeding, tubal ligation and hysterectomy (removal of the uterus) also reduce the risk of ovarian cancer. Surgically removing the fallopian tubes and ovaries reduces the risk of ovarian cancer. However, there is still a small chance of developing primary peritoneal cancer (which is similar to ovarian cancer) after removing the tubes and ovaries. Women with a known BRCA 1 or 2 mutation are recommended to undergo removal of both tubes and ovaries when childbearing is complete. Women at average risk of ovarian cancer who are undergoing hysterectomy should discuss the pros and cons of removing the fallopian tubes and ovaries at the same time.
Symptoms of a “Silent” Disease and Testing
In the past, physicians felt that this was a silent disease, until patients had advanced cancer. We now know that most women have symptoms for several months prior to diagnosis. The symptoms most commonly associated with ovarian cancer include pelvic or abdominal pain, bloating or an increase in abdominal size, feeling full easily and bladder symptoms, including urinating more often and the sudden need to urinate. These symptoms generally occur at least 12 days a month, and are a recent change (presenting for less than 1 year).
Any woman experiencing these symptoms on at least 12 days a month should see an obstetrician/gynecologist. The work-up of these symptoms will include a history and physical examination, including a rectal exam. A transvaginal ultrasound and CA125 (blood test) may also be performed. CA125 is a tumor marker for ovarian cancer. However, it is most helpful in women who have gone through menopause and in women with a known diagnosis of ovarian cancer. CA125 is not specific; many benign (not cancerous) conditions can cause the CA125 to be high.
There is no effective screening method for ovarian cancer currently. Many large studies have been done, evaluating CA125 and transvaginal ultrasound. Screening has not reduced a woman’s risk of dying from ovarian cancer. The largest trial done in the United States enrolled over 78,000 women, and compared women receiving usual care to women undergoing screening with CA125 and ultrasound. The incidence of ovarian cancer was equal in the two groups. Over 3000 women had false positive results (the test was abnormal but there was no cancer), and a third of these underwent surgery. This was associated with an increased risk of complications.1 There are several ongoing trials regarding ovarian cancer screening. However, screening average risk women for ovarian cancer is not recommended.
Women who are suspected or known to have ovarian cancer should be referred to a gynecologic oncologist. Gynecologic oncologists are specialists in gynecologic cancers, including ovarian cancer. Women with ovarian cancer who have surgery performed by a gynecologic oncologist do better than women who are operated on by other types of surgeons.
Treatment: Surgery, Chemotherapy and Clinical Trials
The treatment of ovarian cancer is usually surgery followed by chemotherapy. For some women with stage I ovarian cancer, chemotherapy is not necessary. However, almost all women with ovarian cancer will need chemotherapy. If the cancer appears confined to the ovary, surgery includes removal of the uterus, cervix, both fallopian tubes and ovaries, removing the omentum (a fat pad in the abdomen), taking multiple biopsies, and removing lymph nodes in the pelvis and around the aorta (the major artery in the body). If the cancer is more advanced, the goal is to remove all the cancer that is visible. If that is not possible, the goal is to remove all tumors greater than 1cm. This can involve removing parts of the bowel, the spleen and other organs in addition to removing the uterus, cervix, fallopian tubes and ovaries. Any woman with ovarian cancer should consider treatment on a clinical trial. If a clinical trial is not available or not desirable to the patient, than the woman will most likely be treated with a combination of a platinum drug (for example carboplatin) and a taxane (paclitaxel). Women with advanced ovarian cancer may be a candidate for chemotherapy given directly into the abdomen; this treatment is called intraperitoneal chemotherapy.
For more information on ovarian cancer, please visit Ovarian.org.
1.Buys SS, Partridge E, Black, A et al. Effect of screening on ovarian cancer mortality: the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Randomized Controlled Trial. JAMA 305;2295-303, 2011