Study: 2 Tests Find Ovarian Cancers Early

August 27, 2013

News Review From Harvard Medical School -- Study: 2 Tests Find Ovarian Cancers Early

A screening program using 2 tests appears to catch ovarian cancer at early stages, new research shows. About 3 out of 4 cases of ovarian cancer now are diagnosed after they have spread. Survival rates are low. The new research uses 2 tests that have been tried before. But in earlier studies the tests had abnormal results for many women who did not have ovarian cancer. The new study included more than 4,000 women, ages 50 and older. All were given a blood test each year for a protein called CA-125. Researchers compared their test results and ages with a database to assess their risk of ovarian cancer. They looked at not only the CA-125 level but how it changed over time. In 11 years of follow-up, only 3% of the women were found to be at high risk. They received a second test called a transvaginal ultrasound. Ten women had suspicious results. Biopsies showed that 4 had invasive ovarian cancers. All of them were found in early stages. Two women had tumors that were unlikely to grow. Three had noncancerous tumors. One had endometrial cancer. The journal Cancer published the study. HealthDay News wrote about it August 26.

By Howard LeWine, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

Compared with breast and lung cancer, ovarian cancer is not all that common. Only 22,000 cases are diagnosed each year in the United States. More than 10 times as many women -- 232,000 -- are diagnosed with breast cancer each year. Another 110,000 women are diagnosed with lung cancer.

But the prognosis for cancer of the ovary is so much worse than for breast cancer. It's also slightly worse than for lung cancer. More than 14,000 women will die of ovarian cancer in 2013.

Ovarian cancer is so lethal largely because 3 out of 4 cases aren't found early enough for a surgical cure. Too often, by the time it is found the cancer has already spread beyond the ovaries and throughout the abdomen.

At that late stage, the 5-year survival rate is less than 30%. About 25% of cases are diagnosed early. For them, the outlook is very different. The 5-year survival rate is more than 90%.

This large difference between early-stage and late-stage survival makes ovarian cancer an ideal target for improved early detection.  But finding it early is no easy task. Here's why:

• Symptoms rarely occur when the cancer is confined to the ovary. When symptoms do happen, women often blame the belly discomfort and bloating on age or constipation.
• Early-stage tumors are found only rarely during a routine pelvic exam. That's because the ovaries are deep within the body. They are difficult for a doctor to feel.
• For ovarian cancer, there's no known abnormal growth that can be found before it turns into cancer. (Colon cancer, on the other hand, produces a precancerous polyp. It can be seen and removed during screening with colonoscopy).
• Large trials of the two most promising tests for early ovarian cancer detection have not shown improved survival.

The two tests that have held the most promise are a blood test called CA-125 and transvaginal ultrasound. However, much more often than not, cancer is not the cause of abnormal results in these 2 tests. The result: Many women have surgeries they don't need.

The researchers who led this new study used the same 2 tests. But they tried a different strategy. They did not just look at whether the CA-125 level was normal or abnormal. They also considered whether it rose over time.

Women whose CA-125 blood levels rose at a specified rate were given transvaginal ultrasound. Experts reviewed the ultrasound to determine if changes in one of the ovaries could be caused by cancer. If the answer was yes, those women had surgery to get the definitive answer.

This strategy was compared with using just one high CA-125 level or an abnormal ultrasound. The new strategy increased the rate of early detection of ovarian cancer. And fewer women needed surgery to confirm the diagnosis.  However, even with this refined strategy, 2 out of 3 women who had surgery did not have the kind of invasive ovarian cancer that would have shortened their lives.

The authors also note that some cancers can be missed. That's because some ovarian cancers don't produce CA-125.

What Changes Can I Make Now? 

The authors admit that their strategy should NOT be adopted to screen women at average risk of ovarian cancer for the disease. More research needs to be done.

However, screening with CA-125 and/or transvaginal ultrasound makes sense for some women. Examples include a woman whose mother, sister, daughter, grandmother, aunt or niece had ovarian cancer. Risk probably is also increased for women with 2 or more first-degree relatives who have had breast cancer.  

Carriers of the BRCA1 or BRCA2 gene mutations are at very high risk of ovarian cancer. Many experts recommend that very high-risk women have a CA-125 test and transvaginal ultrasound every 6 months. High-risk women who are past childbearing age often choose to have their ovaries removed. This procedure is 90% effective in preventing ovarian cancer.

For women at average risk, routine screening is not recommended. Pay attention to certain new symptoms that persist for three or more weeks:

• Bloating or swelling of your belly, especially in the lower half
• Pelvic or belly pain or pressure
• Loss of appetite or feeling full after a few bites
• Frequent or urgent urination (feeling like you have to go right away)

These symptoms are not always caused by ovarian cancer. In fact, it is unlikely that ovarian cancer will be the cause, even if you have all four of these symptoms. Still, you should contact your doctor if they persist.

What Can I Expect Looking to the Future? 

New research suggests that cells taken during a Pap test might offer a better screening test for ovarian cancer, and for uterine cancer as well. The test is called PapGene. It analyzes DNA from ovarian and uterine cancer cells that have been shed into the fluid of the cervix.

However, this research is in early stages. Much more testing needs to be done to see if the test can detect these cancers in their early, more curable stages.