Ovarian Cancer: Diagnosis
Tests and Imaging techniques used to diagnose ovarian cancer.
Diagnosis of the Ovarian Cancer
Doctors use many tests to find or diagnose, cancer. They do tests to learn if cancer has spread to another part of the body from where it started. If this happens, it is called metastasis.
For example, imaging tests can show if cancer has spread. Imaging tests, such as ultrasound, computed tomography (CT) scan, or magnetic resonance imagining (MRI), show pictures of the inside of the body. Doctors may do tests to learn which treatments could work best.
If your primary care doctor suspects that you might have ovarian cancer, you should see a gynecologic oncologist. A gynecologic oncologist is a doctor who specializes in treating cancers of the female reproductive system.
Doing laboratory testing of the ovarian and fallopian tube tissues is the only sure way for the doctor to know if an area of the body has cancer. In most cases, this requires surgical removal of these organs.
This section describes options for diagnosing ovarian cancer. Not all tests listed below will be used for every person. Your doctor may consider these factors when choosing a diagnostic test:
- The type of cancer suspected
- Your signs and symptoms
- Your age and general health
- The results of earlier medical tests
While early detection and treatment are important, this is often not possible for ovarian cancer. There are no effective screening methods for ovarian cancer.
The reasons for this are because CA-125, which is tested using blood samples, can be at a higher level due to many benign conditions, especially endometriosis, fibroids, and pelvic inflammatory disease, in addition to pregnancy and menstruation.
Meanwhile, many benign conditions may look cancerous on transvaginal ultrasound. Large clinical trials have shown no benefit in screening the general population for ovarian cancer using these methods.
The annual Pap test that many women receive from their gynecologist does not check for ovarian cancer. It only identifies cervical cancer.
About 70% of epithelial ovarian cancers, particularly high-grade serous cancers, are not found until the disease is in an advanced stage and has spread to other parts of the body, most commonly the abdomen.
The following tests may be used to diagnose ovarian cancer:
1. Abdominal Pelvic Examination
Usually, the first exam is the abdominal-pelvic examination. The doctor feels the uterus, vagina, ovaries, bladder, and rectum to check for any unusual changes, such as a mass. Some cancers are very small before they spread and cannot be reliably felt and detected by pelvic examination.
A Pap test, usually done with a pelvic examination, is not likely to find or diagnose these cancers because that test is used to find cervical cancer.
2. Blood Tests / CA-125 Assay
There is a blood test that measures a substance called CA-125, which is a tumor marker. This marker is found in higher levels in women with ovarian cancer. Women younger than 50 with conditions such as endometriosis, pelvic inflammatory disease, and uterine fibroids may also have an increased CA-125 level.
This test is more accurate in women who have experienced menopause. Other tumor marker tests, such as HE4, are available, but none of these markers are effective for the early detection of these cancers.
3. Transvaginal Ultrasound
An ultrasound probe is inserted in the vagina and aimed at the ovaries and uterus. An ultrasound uses sound waves to create a picture of the ovaries, including surrounding tissues, cysts, and tumors. Researchers are studying whether this test can help with the early detection of ovarian cancer.
4. Computed Tomography (CT) Scan
A CT scan takes pictures of the inside of the body using x-rays taken from different angles. An x-ray is a way to create a picture of the structures inside the body using a small amount of radiation.
A computer combines these pictures into a 3-dimensional image that shows any abnormalities or tumors. Sometimes, a special dye called a contrast medium is given before the scan to provide better detail on the image.
This dye can be injected into a patient’s vein or given as a pill or liquid to swallow. A CT scan can be used to measure the tumor’s size and find out how much cancer has spread. While CT scan technology has continued to evolve, tumors or abnormalities smaller than about 5 millimeters (1/5th of an inch) are difficult to see.
5. Positron Emission Tomography (PET) or PET-CT Scan
A PET scan may be combined with a CT scan (see above), called a PET-CT scan. However, you may hear your doctor refer to this procedure as just a PET scan.
A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive sugar substance is injected into the patient’s body. This sugar substance is taken up by cells that use the most energy.
Because cancer tends to actively use energy, it absorbs more of the radioactive substance. A scanner detects this substance to produce images of the inside of the body. A PET-CT scan may only be used for certain people with ovarian cancer.
6. Magnetic Resonance Imaging (MRI)
An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. MRI can be used to measure the tumor’s size. A special dye called a contrast medium is given before the scan to create a clearer picture. This dye can be injected into a patient’s vein.
This is a medical procedure that removes peritoneal fluid that has built up in a person’s abdomen. This fluid buildup may be called ascites. A sample of the fluid is examined under a microscope for signs of cancer.
A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definitive diagnosis.
A pathologist analyzes the sample(s). A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease.
Biopsies for ovarian cancer are often done as part of the first surgery. During the surgery, doctors may remove as much of the tumor as possible. A tumor sample will be analyzed by a pathologist after the surgery is over.
A biopsy alone is sometimes used if the diagnosis is uncertain or if there is too much tumor to remove initially with surgery. This is usually done when chemotherapy is planned as the first treatment, with possible surgery afterward.
9. Molecular Testing of the Tumor
In addition to genetic testing for inherited, or germline, mutations, your doctor may also recommend running laboratory tests on a tumor to identify specific genes, proteins, and other factors unique to the tumor.
Genetic changes in the tumor cells are called somatic mutations. ASCO recommends that all women with epithelial ovarian cancer who do not carry a germline mutation receive somatic tumor testing.
Somatic tumor testing can look for BRCA1 and BRCA2 mutations in the tumor. And women with clear cell, endometrioid, mucinous, or other types of epithelial ovarian cancer should also be offered somatic testing for a feature called mismatch repair defect (dMMR).
This means the tumor does not repair damage to its DNA very well, which can lead the tumor to develop DNA mutations or changes. Results of these tests can help determine your treatment options.
After diagnostic tests are done, your doctor will review all of the results with you. As noted above, surgery and an examination of the lymph nodes may be needed before results are complete. If the diagnosis is cancer, these test results help the doctor describe cancer. This is called staging.