Researchers report progress in developing a blood test for ovarian cancer, the leading cause of gynecological cancer death.

The test screens blood for four proteins — leptin, prolactin, osteopontin, and insulin-like growth factor II — and may detect early stages of ovarian cancer, say Gil Mor, MD, and colleagues.

"Early diagnosis can help prolong or save lives, but clinicians currently have no sensitive screening method because the disease shows few symptoms," says Mor in a news release. Mor is an associate professor of obstetrics, gynecology, and reproductive sciences at Yale University's medical school.

About Ovarian Cancer

Ovarian cancer often has few early symptoms and is often diagnosed late, when chances of survival are poor, says Mor's study, which appears in the early edition of Proceedings of the National Academy of the Sciences of the United States of America.

This year, about 22,000 U.S. women will be diagnosed with ovarian cancer and 16,210 will die from it, says the American Cancer Society (ACS). The main reason for the poor outcome is the advanced stage of the cancer at the time of diagnosis in most cases. Symptoms appear only in the late stages of the disease.

The overall five-year survival is only 20 percent-30 percent, according to the American College of Obstetricians and Gynecologists (ACOG). However, women diagnosed at earlier stages have a better probability of a cure.

Ovarian cancer rates have gone down since 1991, says the ACS, noting that a woman's risk of getting ovarian cancer in her lifetime is about one in 58. Her risk of dying from ovarian cancer is one in 98, says the ACS.

Early Detection Rare

About 80 percent of ovarian cancer patients are diagnosed with advanced stages of the disease, say Mor and colleagues. "In patients with advanced disease, 80 percent to 90 percent will initially respond to chemotherapy, but [less than] 10-15 percent will remain in permanent remission," they write.

For women diagnosed at early stages (stages I or II), five-year survival is 60 percent to 90 percent, says the study.

"Currently, it appears that the best way to detect early ovarian cancer is for both the patient and her clinician to have a high index of suspicion of the diagnosis in a symptomatic woman," says ACOG. Unfortunately there is no screening test for ovarian cancer that has proved effective in screening low-risk asymptomatic women, they add.

Women at high risk of ovarian cancer (such as those with a strong family history of the disease) may be screened with ultrasound and blood tests, says the ACS. Those methods aren't used for routine screening of women not at high risk.

Women at risk for ovarian cancer are those who have never been pregnant, have decreased fertility, and those who delayed childbearing but did not use oral contraception. Some studies have also linked the use of fertility drugs to an increased risk of ovarian cancer.

Test Not Ready for General Use

"This test should improve our ability to accurately detect premalignant change or early stage ovarian cancer in asymptomatic women at increased risk for the development of ovarian cancer," write Mor and colleagues.

However, more work is needed before the test can be used by the general public, say the researchers. "There is significant need for further improvement of the [test] reported here if [it] is to be used for general population screening," they write.

About the Test

The test was tried on 106 healthy women and 100 with ovarian cancer. Each of the four proteins had been mentioned as possible markers, but this is the first test to screen for all four at once, say the researchers.

The test's results relied on all four proteins. "No single protein could completely distinguish the cancer group from the healthy [group]," says the study.

Could those four proteins also indicate other kinds of cancer? That "must be investigated rigorously," say the researchers, noting that some cancers already have well-established detection methods (such as mammography for breast cancer).

Progress Against Female Reproductive Cancers

News of the ovarian cancer blood test comes almost six months after another cancer of the female reproductive system was in the headlines.

Last November, researchers reported that they were making progress in developing a vaccine against two strains of the human papillomavirus (HPV) that account for most cervical cancer cases.

A large clinical trial of the vaccine is under way.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: Mor, G. Proceedings of the National Academy of Sciences of the United States of America, May 9-13, 2005, early edition. News release, Yale University Medical News. News release, Proceedings of the National Academy of the Sciences of the United States of America. American Cancer Society: "How Many Women Get Ovarian Cancer?" American Cancer Society: "How Is Ovarian Cancer Found?" WebMD Medical News: "Cervical Cancer Vaccine Passes Major Hurdle." American College of Obstetricians and Gynecologists.