By Debbie Saslow, PhD
For years, patients, doctors, and researchers have been trying to find a way to catch ovarian cancer early, when it's most treatable. For women, the chance of getting ovarian cancer is about 1 in 70. In most cases, the cancer is found at an advanced stage and survival is, sadly, quite low.
Most women get tested regularly for breast cancer and cervical cancer, and hopefully colorectal (colon) cancer. Why aren't they checked for ovarian cancer, too? Unfortunately we don't have tests like mammograms or Pap tests for the ovaries. Doctors often do a pelvic exam, which includes checking the ovaries, but this exam rarely finds ovarian tumors unless they have grown very large.
Some other tests, like the CA-125 blood test and transvaginal ultrasound, have been studied to see if they can be used to test for ovarian cancer, but none have proven to be accurate enough to consistently find cancer.
The CA-125 test measures a protein that can be found in the blood of many women with ovarian cancer. However, other conditions, including but not limited to normal ovulation, endometriosis, pelvic inflammatory disease, can also raise CA-125 levels in the blood, and some women with ovarian cancer may still have normal CA-125 levels. And transvaginal ultrasound can find a mass on the ovaries, but it cannot determine whether or not that mass is cancer. That means more invasive tests like biopsies, which carry their own risks, are needed.
Because of these problems, these tests are not recommended for women at average risk, but they may be used for women at high risk or who have symptoms that may suggest ovarian cancer. Even in these women, however, these tests are problematic and their use is limited.
The results of one large recent study looking at whether ovarian cancer screening could find cancers early enough to save lives compared testing women yearly with both CA-125 and ultrasound to no testing. Nearly 80,000 women participated. Three-fourths of the ovarian cancers diagnosed in both the tested group and the untested group were already advanced stage, meaning they had spread to other parts of the body, making treatment difficult. Making things even more problematic, more of the women who had been tested had surgery to remove their ovaries, but it turned out that they did not have ovarian cancer. The surgeries led to severe complications in about 15% of the women, such as heart problems, bowel injury, blood clots, and infection. The bottom line: testing did not save any more lives compared to not testing, did not find cancer at an earlier stage, and led to many more unnecessary surgeries that sometimes resulted in serious complications.
The definitive large ovarian cancer screening study, which is expected to confirm the success or failure of ovarian cancer testing, currently is being done in the United Kingdom. This study, with more than 200,000 women, also compares testing with CA-125 and/or ultrasound to no testing, but women who are at intermediate or high risk of ovarian cancer have repeat CA-125 testing to check for rising levels over time. This is because changes in their CA-125 levels could be a good predictor of which women develop ovarian cancer. The UK study will be completed in 2014.
Are there any newer tests that are more reliable? There has been research and several attempts to develop a blood test for ovarian cancer. These are based on measuring genes or proteins that may be present in higher or lower amounts in women with ovarian cancer compared to women who do not have ovarian cancer. None of these tests has yet been proven to be accurate, effective, or to save lives. No test has been validated (studied in large groups of women to see if it actually helps find ovarian cancer early) nor undergone FDA review.
So without an accurate, recommended screening test, what should women do to protect themselves from ovarian cancer? Even though ovarian cancer has been called the silent killer, many women with ovarian cancer actually do have symptoms. These include:
- Pelvic or abdominal pain
- Difficulty eating or feeling full quickly
- Urinary symptoms (urgency or frequency)
These symptoms are more likely to persist in women with ovarian cancer than women in the general population. However, they are not unique to ovarian cancer, and in fact most women who have these symptoms will not have ovarian cancer. If these symptoms are new and occur repeatedly for at least a month and can't be explained, an evaluation for ovarian cancer is recommended. However, only an invasive procedure like laparoscopy or open surgery can confirm that a woman has ovarian cancer, and these procedures carry their own serious risk.
The American Cancer Society, other health organizations, and ovarian cancer advocacy groups encourage and fund research to develop an accurate and valid test for early detection of ovarian cancer. In the meantime, organizations do not recommend screening for women at average risk.
Dr. Saslow is the director of breast and gynecologic cancer for the American Cancer Society.