Novel Blood Test Detects Ovarian Cancer
A pilot study by researchers at The Ohio State University Comprehensive Cancer Center found that a novel blood test that screens for microRNAs can reliably detect ovarian cancer, even among patients who test negative for the deadly disease with the widely used CA-125 blood test.
“The early detection of ovarian cancer is the Holy Grail,” says lead investigator Dr. David E. Cohn, a gynecologic oncologist and researcher at The Ohio State University Comprehensive Cancer – James Cancer Hospital and Solove Research Institute.
“Too many women die from ovarian cancer because it often is detected too late, when the prognosis is poor. We are trying to use a blood test to detect ovarian cancer earlier, when the prognosis is better.”
In 2008, an estimated 20,000 women will be diagnosed with ovarian cancer, and more than 15,000 will succumb to the disease.
The findings are published in the journal Gynecologic Oncology. First author Dr. Kimberly Resnick also presented the findings at an international meeting on molecular markers in cancer in Hollywood, Fla.
“We can clearly define the microRNA pattern in the blood of patients with this disease,” Cohn says. These findings could have implications for other cancers, as well, he says.
MicroRNAs (miRNAs) are single-stranded RNA molecules that help regulate the proteins made by cells. MiRNAs are smidgens of genetic material measured in a few nucleotides of length. A gene, in comparison, can be tens of thousands of nucleotides long.
“We hypothesized that there would be a different miRNA expression between the blood of patients with ovarian cancer and those without, and our study supported the hypothesis,” says Resnick, who is a gynecologic oncology fellow and researcher at Ohio State’s Comprehensive Cancer Center – James Cancer Hospital and Solove Research Institute.
The study of 28 ovarian cancer patients and 15 cancer-free women found that patients who have ovarian cancer have a certain pattern of miRNAs in their blood that is similar to the pattern of miRNAs found in the tumors from patients with ovarian cancer, Cohn says. The control group without ovarian cancer lacked this specific pattern of miRNAs in their blood.
“Further study is needed, but we are hoping that one day this could become a standard screening test for ovarian cancer, similar to the PSA screening now routinely offered for men to detect prostate cancer,” says Cohn. “But just like any test, we must validate it in larger studies, so such a test is years away from being commercially available on the market.”
Cohn, Resnick and fellow collaborator Dr. Carlo M. Croce, who is the director of human cancer genetics at Ohio State, have applied for a patent on developing this technology as a screening blood test for ovarian cancer.
The CA-125 blood test measures the level of a protein released by ovarian cancer cells. That protein is known as a tumor marker because it is usually present at higher levels in women with ovarian cancer. CA-125 is most commonly used to detect recurrent ovarian cancer in women who have been previously treated.
However, the CA-125 level can be elevated in men and women who do not have cancer and only half of patients with early stage, curable ovarian cancer will have an elevated CA-125 level. In addition, 25 percent of patients who have ovarian cancer will register a normal CA-125 blood test level, Cohn says.
Although CA-125 testing is helpful for monitoring a patient’s response to treatment, this test alone cannot diagnose ovarian cancer, nor is it effective in screening healthy women for ovarian cancer. A high level of CA-125 can also be due to causes other than cancer, he says. These include inflammatory conditions of the abdomen; recent surgery; gynecologic conditions such as fibroids, endometriosis or ectopic pregnancy; or a ruptured cyst.
Ovarian cancer is difficult to diagnose because there is no reliable screening test available, says Resnick. Symptoms of ovarian cancer may include bloating; pelvic or abdominal pain; difficulty eating or feeling full quickly; or urinary symptoms of frequency or urgency.
“Unfortunately, right now we have poor screening tools for this disease, and 80 percent of the time the disease is diagnosed at an advanced stage,” says Resnick. “We need a screening test that can identify this disease at an earlier stage and identify patients who are at risk for developing this disease.”