Researchers have found a new way to use an existing blood test that may provide a way to screen women for ovarian cancer, perhaps in time to cure more women of the deadly disease.
They said combining a test that measures levels of a certain protein along with a way of measuring risk of the disease helped spot early stage cancers in otherwise healthy women.
If detected early, ovarian cancer can be cured, but more than 70 percent of women have advanced disease by the time they are diagnosed, said Dr. Karen Lu, of the University of Texas M.D. Anderson Cancer Center, who led the study.
The findings were released on Thursday ahead of the American Society of Clinical Oncology meeting in June.
"This may be pointing the way toward developing a 'mammogram' if you will for ovary cancer," ASCO president Dr. Douglas Blayney, of the University of Michigan Medical School, said in a telephone interview.
Ovarian cancer kills 15,000 U.S. women each year.
"Clearly there is a need for coming up with an effective strategy to detect ovarian cancer early," Lu said in a telephone interview.
She and colleagues studied a new way to use the cancer antigen or CA-125 test, which measures levels of a protein that is elevated in ovarian cancer cells.
The CA-125 test can detect rising levels of this protein, and is typically used to see if ovarian cancer has come back. But it is less sensitive in early stage cancers because levels of CA-125 can also rise from non-cancerous conditions, especially in pre-menopausal women.
Lu's team used the CA-125 test in combination with the Risk of Ovarian Malignancy Algorithm, a mathematical formula that calculates a woman's risk of having ovarian cancer based on age, CA-125 level and CA-125 levels over time.
The team studied women over age 50 who had no significant family history of breast or ovarian cancer, and put them into three groups.
Those at low risk got annual blood tests. Women deemed at intermediate risk were called back for a repeat test in three months. If the risk appeared high, they were referred for a transvaginal ultrasound, which uses soundwaves to create a picture of the pelvis.
The team found three invasive cancers in 3,238 women who participated in the study — all early stage and potentially curable.
"What's looking promising is the trend over time," Lu said. "You could have a very low value and all of a sudden it goes very high. That is a trigger," she said.
Lu said the findings are not enough to change practice. But researchers in Britain are evaluating the blood test and risk algorithm combination in a study of more than 200,000 women. Results of that study are due in 2015.
"We'll have the definitive answer in a short amount of time," she said.