Definition & Overview
An ovarian cancer screening refers to a series of tests performed to detect the presence of ovarian cancer at its earliest stages, even before symptoms begin to show. These tests are performed based on the fact that treatment success rates are significantly affected by how early or how late the cancer is detected. The earlier a cancer is found, the higher the chances are of curing it.
Cancer screening tests are very limited and can only diagnose a select number of cancer types, one of which is ovarian cancer. However, people undergoing the procedure should be aware of the accuracy rating of such tests. As of present time, there is no screening test for ovarian cancer that offers 100% accuracy. These tests, however, are constantly under testing and analysis for further improvements.
Who Should Undergo and Expected Results
Among the types of cancer that affect women, ovarian cancer is ranked as the fifth most common. It is also the most fatal among all gynecologic cancers. Statistics show that about one in 70 women is at risk of developing this type of cancer.
Some women are at a higher risk of developing ovarian cancer, while some only have an average risk. Women with an average risk of ovarian cancer are those who have:
- A history of infertility
- Undergone assisted reproductive therapy, such as IVF in the past
- A history of endometriosis
- Undergone hormone replacement therapy
- A history of breast cancer
Meanwhile, women who are at a higher risk for ovarian cancer are those who:
- Has a first-degree family history of ovarian cancer
- Has had breast cancer diagnosed at age 40 or earlier
- Has two or more relatives with a history of breast cancer who were diagnosed before they turned 50
- Has two or more close relatives with a history of ovarian cancer
While ovarian cancer screening tests are expected to determine whether a person has ovarian cancer, it does not always yield accurate results. In fact, they may lead to false positive or false negative results. Thus, different screening tests are usually measured based on their sensitivity as well as specificity. The former refers to the probability of the test yielding a positive result for a patient who is really affected by the disease. This means that a truly sensitive test should positively diagnose women who have cancer and undergo screening. On the other hand, specificity refers to the probability of a negative result on a patient that is not affected by the disease. This means that if a test diagnoses 10 women to have ovarian cancer, but only two of them are actually affected, the test is not considered specific. Screening tests for ovarian cancer don’t have high sensitivity and specificity ratings yet, so they are still being improved.
How Does the Procedure Work?
The manner in which an ovarian cancer screening test is conducted depends on the specific type of test. These tests include the CA125 blood test and transvaginal ultrasound.
The CA 125 blood test is a procedure that screens the blood for the existence of the CA 125, which is a known tumour marker or a protein-based chemical originating from cancer cells. The CA 125 circulates through the bloodstream and high levels of it in the blood are an indication of the presence of ovarian cancer. Still, only about 50% of women actually produce measurable amounts of CA-125 especially when the screening is performed at the earliest stages of the disease, so the risk of misdiagnosis is still present. There are also cases wherein the woman has elevated levels of CA-125 that are caused by an entirely different health condition.
A CA 125 test is done by getting a blood sample that is then subjected to a series of tests. If CA 125 is detected, it will be measured per milliliter to compare its quantity with the normal level, which should be less than 35 units per milliliter; anything higher than this is an indication of a possible ovarian cancer.
The transvaginal ultrasound, on the other hand, is a screening examination that is performed by inserting an ultrasound probe into vagina to assess the condition of the ovaries. It is capable of producing good quality images of the ovaries than by placing an ultrasound scanner over the patient’s abdomen, as is usually done. It works by checking the size of the ovaries to detect any changes or abnormalities, as well as checking the texture of the ovaries and detecting cysts. If cysts are detected, physicians will normally perform follow-up procedures to determine whether they are benign or malignant; also, they need to perform surgeries within a particular timeframe depending on the rate of the tumor’s growth. In many cases, surgery is immediately performed.
However, a transvaginal ultrasound leaves the rate of accuracy dependent on the skill of the doctor performing the test. There is currently no strong evidence that this scan is capable of picking up ovarian cancer, especially in its early stages.
Thus, to fully gauge a person’s risk of having ovarian cancer and increase the expected accuracy of both tests, observations made through ultrasound and other methods of screening such as the CA-125 blood test, are simultaneously taken into account. The final index score usually helps doctors determine the next steps to be undertaken.
Possible Complications and Risks
The main risk involved in undergoing ovarian cancer screening lies in the fact that the existing types of screening tests for ovarian cancer are not 100% reliable, which means that they do not guarantee a correct diagnosis at all times. If the test diagnoses ovarian cancer that is not there, the patient may unnecessarily undergo treatment that exposes her to some complications and risks. On the other hand, there is also the risk of not finding cancer that is really there, which can prevent a patient from seeking the medical help that she needs.
Coleman RL, Ramirez PT, Gershenson DM. Neoplastic diseases of the ovary: screening, benign and malignant epithelial and germ cell neoplasms, sex-cord stromal tumors. In: Lentz GM, Lobo RA, Gershenson DM, Katz VL, eds. Comprehensive Gynecology. 6th ed. Philadelphia, PA: Elsevier Mosby; 2012:chap 33.
Morgan M, Boyd J, Drapking R, Seiden MV. Cancers arising in the ovary. In: Niederhuber JE, Armitage JO, Doroshow JH, Kastan MB, Tepper JE, eds. Abeloff's Clinical Oncology. 5th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2013:chap 89.
National Cancer Institute. BRCA1 and BRCA2: cancer risk and genetic testing. Updated 1/22/2014. Available at: www.cancer.gov/cancertopics/factsheet/Risk/BRCA. Accessed November 26, 2014.