Laboratory Tests for Ovarian Cancer
In addition to imaging studies, other tests may be used to help verify a diagnosis of ovarian cancer. These include blood analyses for tumor markers, tests for genetic mutations, and the microscopic examination of ovarian cells.
CA125 (or OC-125) is a blood protein known as a tumor marker. Research has shown that roughly 85 percent of women with clinically apparent ovarian cancer have increased levels of CA125. The normal blood level of CA125 is less than 35 units per milliliter (< 35 U/mL). As the CA125 level is increased above 35 units (>35 U/mL), the likelihood of ovarian cancer is increased, particularly among women who are postmenopausal.
CA125 is not a fool proof test, as the protein also is increased during the first trimester of pregnancy, during menstruation, and in the presence of noncancerous illnesses (e.g., liver failure, pelvic inflammatory disease, endometriosis) and cancers of other sites (e.g., breast, lung, pancreas, colorectal). Some ovarian cancers may not produce enough CA125 to cause a positive test result.
BRCA1 and BRCA2 are genes that may be mutated in individuals with breast or ovarian cancer. Women who are at high risk because of a positive family history of ovarian and/or breast cancer should be offered BRCA1 and BRCA2 mutation screening. Such screening will help to establish the degree of risk in women with suspected disease.
Fine-needle aspiration cytology gathers cells from tissues that are suspected of containing cancerous growths. A fine, hollow needle is attached to a syringe and is then inserted into the suspicious mass. The needle is pushed back and forth to free some cells, which are aspirated (drawn up) into the syringe and smeared on a glass slide for microscopic analysis. Sometimes CT scan or ultrasound is used to guide this procedure.
Tissue Sampling to Diagnose Ovarian Cancer
Once a growth in the pelvic region has been identified, it is necessary to obtain suspicious tissue by direct biopsy (removal of a sample of tissue) for analysis under a microscope. Although other procedures may suggest a malignancy, this is the primary method to confirm a diagnosis of ovarian cancer.
Biopsy typically is performed during surgery. The estimated extent of disease will determine the type of surgical procedure chosen. Laparotomy, surgery performed through an abdominal incision, is the most invasive procedure (i.e., it involves a large incision and more surgical instruments), but it is also the most accurate method for obtaining a biopsy and evaluating the spread of disease.
Laparoscopy (i.e., surgery performed using a tube containing a light and a camera that is inserted into the pelvic cavity through a small incision) is used if the cancer is thought to be confined. The goals of exploratory surgery is to gather biopsies for diagnosis and staging, pinpoint the origin of the tumor, and remove all cancerous growths that are larger than 1 centimeter.
In patients with advanced cancer who cannot tolerate laparotomy, CT- or ultrasound-guided needle biopsy may be performed.
If the physician suspects that other organs (e.g., bowel, kidneys, bladder, lungs) are involved, additional imaging studies may be performed. These tests include the following:
- Barium enema (introduction of a contrast agent into the rectum for x-ray examination of the bowel)
- Chest x-ray (to rule out metastasis to the lungs)
- Intravenous pyelogram (IVP; x-ray examination of the kidneys and ureters after injection of contrast agent)