How we diagnose ovarian cancer
An ovarian cancer diagnosis can only be confirmed by taking a tissue sample (biopsy) and examining the cells under a microscope.
Laura (not her real name) saw me for a first consultation and was quite distressed because she was told by her doctor that she had ovarian cancer. Upon review of the tests that had been done, I felt there was at least a small chance that this was not ovarian cancer, but a benign ovarian mass. Let's take a closer look at how ovarian cancer is diagnosed.
If ovarian cancer is suspected, your doctor may conduct a pelvic exam and also request medical imaging scans and blood tests. Ideally, these tests will determine the risk that the patient has ovarian cancer. For some patients, the risk would be very small (e.g. less than 1%) and often we can reassure these patients. Some patients display many hallmarks of ovarian cancer and their risk of having ovarian cancer would be very high (e.g. greater than 90%). For the majority of patients we need to check and organise a biopsy, which then confirms or excludes ovarian cancer.
During a pelvic exam, the doctor attempts to feel the ovaries and uterus for size, shape and feels for any masses or lumps. However, normal ovaries and most early ovarian tumours are very small and difficult to feel in the early stages, so a pelvic examination will be not sufficient alone and further investigations are needed.
During investigations for ovarian cancer, your doctor will request a transvaginal ultrasound. This is the preferred type of ultrasound as it provides a clearer picture of the ovaries. A sonographer (medical imaging professional) will insert a small transducer probe into the vagina. The wand is covered with a disposable plastic sheath and gel to make it easier to insert. This procedure may feel uncomfortable, but it should not be painful.
The transvaginal ultrasound probe can be advanced very close to the ovaries and they can be seen very clearly. An ultrasound through the belly is less assuring because there can be tissue and bowel gas between the ultrasound probe, the abdominal wall and the ovaries.
Tumour markers are substances, usually proteins, found in the blood that are often also found in cancer patients. The most common ovarian cancer tumour marker test is CA125, but can also include CA19.9 and HE4. Unfortunately, tumour marker levels in the blood can be raised for other reasons that are not related to cancer therefore the test is not completely reliable. It is not a useful test for women who do not have symptoms. I discuss more about this in my previous article How reliable are tumour marker tests for ovarian cancer?
If the tumour marker or ultrasound tests indicate there is further investigation required, explorative surgery may be recommended.
Explorative surgery (biopsy)
During a biopsy, doctors take a tissue sample from the suspicious mass. A frozen section examination is conducted by a pathologist, where the biopsy is then examined under a microscope for cancerous cells. This happens during the surgical procedure while the patient is asleep. If cancer is confirmed, the tumour is removed during the same procedure. Ovarian cancer surgery is usually done through an abdominal incision and will typically remove the uterus, fallopian tubes and both the ovaries. During the procedure the doctor will determine how far the cancer has spread. Sometimes this requires surgery to remove the omentum (a fat pad covering the bowels) and some lymph nodes, which is all done in the same surgical procedure.
Stages of ovarian cancer (FIGO system)
If diagnosed with ovarian cancer, a cancer stage will be given:
- Stage I: Cancer is in one or both ovaries only.
- Stage II: Cancer is in one or both ovaries and has spread to other organs in the pelvis (uterus, fallopian tubes, bladder or bowel).
- Stage III: Cancer is in one or both ovaries and has spread beyond the pelvis to the lining of the abdomen (peritoneum) or to nearby lymph nodes.
- Stage IV: The cancer has spread further to distant organs such as the lung or liver.
In summary, we currently don’t have reliable non-invasive tests to diagnose ovarian cancer, and the only way to confirm a diagnosis is by biopsy, which involves a procedure of some sort. Researchers are presently looking for better ways to screen for ovarian cancer.
For more information on diagnosing ovarian cancer, visit the Ovarian Cancer page.
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