Ovarian cancer is a condition that is characterized by the uncontrolled growth of the cells of the ovaries. The ovaries are the reproductive glands that women have on each side of their uterus, located within the lower abdomen. The ovaries serve a couple of functions. They produce progesterone and estrogen, which are the hormones that support the development of a woman’s secondary sex characteristics and that regulate the reproductive cycle. They also develop eggs, which are then released into the Fallopian tube once per month, to travel to the womb in preparation for fertilization.
Ovarian cancer is a common condition and is the fifth most common cause of cancer death in women. The American Cancer Society reports that the lifetime risk of developing ovarian cancer is around 1 in 75. Approximately 22,280 new cases of ovarian cancer are diagnosed every year in the United States, and around 14,240 women each year die from ovarian cancer. Invasive ovarian cancer is a more common cause of death than uterus and cervical cancers, which are more easily detected and more prevalent. Around 20% of ovarian cancers are detected before they have managed to spread from the ovary.
An ovarian tumor can be malignant or benign. It is not typically possible to tell whether a tumor is benign or cancerous until there has been a biopsy performed. Tests can help to identify which of the three tumor types are present:
- Epithelial tumors: This is the most common kind of tumor. It begins in the epithelial cells, which are on the outside of the ovary.
- Germ cell tumors: These are very rare, accounting for fewer than two percent of all ovarian tumors. They occur in the egg-producing cells and are most often found in young women.
- Stromal tumors: Just one percent of tumors are this type. They derive from connective tissues in the ovary, which are the tissues that produce estrogen and progesterone.
Benign tumors will not metastasize, but cancerous tumors, if untreated, will spread from the ovary to other areas, including the uterus, rectum, bladder, and lining of the abdomen. Cancerous cells may eventually reach lymph nodes and then spread through the rest of the body.
Calculating the Risk
The key risk factor for ovarian cancer is family history. If anyone in the family (maternal or paternal side) has had ovarian cancer, this can mean that the woman is at a greater risk of developing it herself. The American Cancer Society reports that around five to ten percent of cases of ovarian cancer are thought to be hereditary.
People who have a mutation in the BRCA1 or BRCA2 gene are at greater risk of ovarian cancer. Someone who has BRCA1 mutation is estimated to have a risk of 35% to 70%, while someone with a BRCA2 mutation has a risk of 10 to 30%. If someone has neither of those mutations, then their risk is around 2%.
Women under the age of 40 are less likely to have ovarian cancer. The risk increases with age, and around have of all cases are in women who are 63 years old, or older. Most cases of ovarian cancer develop after menopause. Ovarian cancer is more commonly found in women who are Caucasian than in African American women.
Women who have a personal history of breast cancer are at a greater risk of developing ovarian cancer. The risk is also slightly greater in women who have never had children, those who were obese while young adults, and those who are taking or have taken fertility drugs or hormone replacement therapies. There is a slightly decreased risk associated with women who have had a tubal ligation. It is thought that low-fat diets, oral contraceptives, and having had children can help to reduce the risk of ovarian cancer.
Ovarian cancers often go undetected because there is no reliable screening method, and the symptoms, especially early ones, are nebulous. For example, symptoms can include:
- Pelvic pain
- Chances to urinary urgency or bowel habits
- Loss of appetite, nausea, and indigestion
- Bloating, swelling or discomfort in the abdomen
The US Preventative Services Task Force reaffirmed a recommendation against screening for ovarian cancer in asymptomatic women with low-risk factors for ovarian cancer. The reason for this is that there is not currently a reliable method for detecting ovarian cancer in those who are asymptomatic.
Gene tests and multimarker approaches to testing are being evaluated as a way of improving detection rates. The OVA-1 blood test is one test that may be useful. This test measures the levels of five key proteins, to categorize tumors as being high or low risk.
For now, the best approach is thought to be regular physicals, pelvic exams, and having an awareness of family history.
Available Lab Tests
CA-125 is the main lab test that is used to detect and monitor ovarian cancer in women who have symptoms of the condition. Still, it is not recommended for use as a screening method.
HE4 is a new tumor marker that is showing promise, and that can be used to monitor epithelial ovarian cancer in patients that are undergoing treatment.
BRCA-1 and BRCA-2 are genetic tests that can indicate whether a person is at a higher risk of developing ovarian cancer. Still, they cannot be used for diagnosis or to monitor the condition.
Some other tests can be used to monitor or detect ovarian tumors. For example, epithelial tumors can be monitored using tests for carcinoembryonic antigens. However, this test is less sensitive and less specific than CA-125. Germ cell tumors can be tested for using AFP, hCG, and LD tests, and stromal tumors can be tested or with Inhibin. None of these tests are sensitive or reliable enough for widespread, routine screening of the population.