A new screening approach to detect early stage ovarian cancer in post-menopausal women has proven promising, researchers said of results to a study released Thursday.

"More than 70 percent of ovarian cancers are diagnosed when they have already grown to an advanced stage, so identifying a reliable screening test for early-stage disease would be like finding the Holy Grail," said the study's lead author Karen Lu, of the University of Texas' Anderson Cancer Center.

"This study is one step forward in that direction. If confirmed in larger studies, this approach could be a useful and relatively inexpensive tool for detecting ovarian cancer in its early, more curable stages," she said.

The results were presented by the American Society of Clinical Oncology (ASCO) ahead of its annual conference, to be held June 4-8 in Chicago.

The new method uses a mathematical model to assess trends in CA-125 blood test results - a protein known to rise during the cancer's development - and a patient's age. The model is then "followed by transvaginal ultrasound and referral to a gynecologic oncologist, if necessary," researchers said.

For up to eight years, the study followed 3,238 post-menopausal women aged 50 to 74 who had no significant family history of breast or ovarian cancer, and the accuracy of using the mathematical model followed by ultrasound was 99.7 percent, indicating few false-positives using the approach, researchers said.

A larger study involving more than 200,000 women is currently underway in Britain, with results expected by 2015.