Designing an effective test to detect ovarian cancer

Current diagnostic tests for ovarian cancer are woefully ineffective for early detection of the disease, say researchers at Stanford University School of Medicine.

A new study finds that in order to make a significant dent in the mortality rate for the deadly ovarian cancer, the tests would have to be able to detect tumors of less than 1 cm in diameter, or about 200-times smaller in mass than those currently used to assess potential new tests.

Still, if that hurdle can be overcome, there is good reason to believe that testing could make a big difference: The window of opportunity for treating these clinically undetectable cancers before they become life threatening is surprisingly long: about four years.

The research will be published in the July 28 issue of the open-access journal PLoS Medicine.

“We are miles away from detecting the most deadly ovarian tumors at this early stage,” said Stanford biochemistry professor Patrick Brown, MD, PhD, “but now we have a chance of actually designing an effective test that will allow us to treat them before they become deadly.” If a blood test is to be effective, said Brown, it will likely require identifying new markers that are never produced by normal cells ??” rather than testing for abnormally high levels of proteins detectable in normal blood, as current tests do. Other possible strategies might rely on new molecular imaging methods or fluid samples from the uterus or vagina ??” in which tumor markers are likely to be more concentrated.

Ovarian cancer is particularly feared by women and their physicians because the disease is so difficult to detect in its early stages. Symptoms are vague, and often don’t occur until the tumor is already several centimeters in diameter. At this point it may have already spread to surrounding organs and tissues. What’s more, several published studies have indicated that the current screening tests deliver many false positive results and don’t reduce mortality from the disease.

“Reliable early detection would save so many more lives than many new blockbuster anticancer drugs,” said Brown, a Howard Hughes Medical Institute investigator and a member of the Stanford Cancer Center, who collaborated with the non-profit Canary Foundation to conduct the research. The foundation is dedicated to the early detection of many types of cancer. “If we can do this, which is no small challenge, the potential to go from a less than 20 percent chance of surviving five years to a relatively minor surgery that would have a very high cure rate is huge,” he said.

Part of the difficulty in designing an effective test lies in the fact that there is more than one type of ovarian cancer. The most deadly, known as serous ovarian cancer, accounts for about 50 percent of all cases of ovarian cancer but it is responsible for at least 80 percent of deaths from the disease. In contrast to other types of ovarian tumors, which can grow to be quite large before spreading to other locations, serous ovarian tumors usually metastasize before they are diagnosed.

Source: Stanford University Medical Center, USA

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