Ovarian Cancer Tests and Screening: An Overview

When people hear how deadly ovarian cancer is, they are often shocked and want to take action. Some begin to urge that all women be screened annually for ovarian cancer. While these statements may be made with the best of intentions, we do not currently have the tools to screen average risk women for this disease.

Following is an overview of the latest studies and data on ovarian cancer screening.

Screening

Screening refers to testing the general population, or at least those who appear well, for a disease or condition. This type of screening does not take into account risk factors or exposure to pathogens. Early detection is also frequently included in the common use of the word screening. Surveillance or selective screening is a way of singling out a sub-population to test or watch for a specific disease. Often, women at high risk of developing ovarian cancer will take part in selective screening or be monitored by their health care provider.

In order to be effective at a population level, a screening test needs to identify a disease correctly. In the case of ovarian cancer, false positives can lead to complications from unnecessary surgery, while false negatives could allow the disease to spread before it is correctly identified.

There are no known screening tests for ovarian cancer, however three trials are using currently available tests to try to develop a method for screening women. Conclusions based on the results of major studies vary significantly.

United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS)

This trial, currently underway in the United Kingdom, is examining the impact of screening for ovarian cancer on mortality. More than 200,000 women are enrolled in the study. Of those women, 50,000 will receive an annual CA-125 blood test and 50,000 will receive a transvaginal ultrasound. The other 100,000 women are the control group—they will get the standard of care, which means no screening. Women from the experimental arm who have an abnormal result will be tested further with ultrasound and blood tests. If those tests are abnormal the woman will be referred to a gynecologic oncologist. The trial will continue gathering data through at least 2014.

United States arm of UKCTOCS

A small-scale screening study was presented at the 2010 meeting of the American Society of Clinical Oncology (ASCO), which lent support to the development of a screening method for ovarian cancer. The study, authored by Dr. Karen Lu of MD Anderson Cancer Center, followed more than 3,000 women for eight years, measuring their CA-125 levels annually. These women were aged 50 to 74, and had an average risk of developing ovarian cancer. Those women whose CA-125 levels were rising over a number of years were given an ultrasound, and if the ultrasound showed positive results (i.e., presence of a tumor), underwent surgery. Of the 3,328 women, 85 had an ultrasound and eight had surgery. The surgeries led to diagnosing five ovarian cancers—three invasive and two borderline—all in early stage (1-2). Two patients had benign ovarian tumors and a third had an endometrial cancer. Two women with borderline ovarian cancer were diagnosed through other methods.

This study shows that monitoring CA-125 levels over time in women of average risk for ovarian cancer is feasible and requires no more than three operations for each case of cancer diagnosed. The US arm is a small study; we await the results of the large scale UKCTOCS study to provide more definitive information. However, these results contradict the results of the PLCO study described below.

Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO)

Results of this large screening trial were presented at the 2011 ASCO meeting. More than 78,000 women were randomized between normal care and screening arms. Women in the screening arm were given an annual CA-125 test for six years and a transvaginal ultrasound for four years. The study was designed to show the effect of screening on overall survival by following patients for 13 years. The study showed that women in the screening arm of the study were more likely to be diagnosed, but were also more likely to die of ovarian cancer. Additionally, more than 3,000 women had surgery based on false positive results, leading to more than 160 women with serious complications. Screening with this particular protocol did not reduce ovarian cancer mortality.

Diagnosis/Referral

In addition to the tests we already have, two new tools have been developed to help triage and diagnose women who may have ovarian cancer.

The first tool, Ova1, is an FDA-cleared test to help determine if a woman’s pelvic mass is malignant or benign. This blood test evaluates five biomarkers and will tell a physician if the mass is likely to be malignant. If it is, the woman should be referred to a gynecologic oncologist for surgery. A test that accurately predicts whether a pelvic mass is malignant could help doctors determine whether to operate on a woman, since all surgery carries the risk of complications.

Another new test is the HE4 blood marker, which is FDA-approved to monitor recurrence in women with ovarian cancer. The FDA recently approved the use of the CA-125 with the HE4 blood test to determine the likelihood that a pelvic mass is malignant. Three-quarters of women with ovarian cancer will experience a recurrence of the disease, which makes ongoing monitoring an important issue.

Symptoms

Although there is no early detection test for ovarian cancer, women with the disease do experience symptoms: bloating; pelvic or abdominal pain; difficulty eating or feeling full quickly; and urinary frequency or urgency. Data show that women with ovarian cancer experience these symptoms more often than the general population.

To help women track the four relevant symptoms, the Ovarian Cancer National Alliance will release an interactive symptom diary app this fall. The app can be used on a smartphone or computer to learn about risk factors associated with ovarian cancer and track symptoms. Women without a smartphone can download a print version of the symptom diary at www.ovariancancer.org/diary. Both the app and printable diary are available free of charge on the Alliance website.