Researchers at the University of Texas Southwestern Medical Center announced Wednesday they have found a new blood biomarker that enables close to 98 percent accuracy in predicting the spread of prostate cancer to regional lymph nodes.

Their study is published in the March 1 issue of Clinical Cancer Research.

When cancer spreads beyond a solid tumor, it often does so at a microscopic level that typically cannot be identified by conventional imaging methods such as CT scans. The new blood test measures levels of endoglin, a plasma biomarker that has been previously shown to predict the spread of colon and breast cancer.

In this study, researchers concluded for the first time that endoglin could help predict whether a patient's prostate cancer would spread beyond the solid tumor site into their lymph nodes.

"For prostate cancer, we have hit the limit of our ability to classify risk in these patients before initial surgery," said study author Shahrokh Shariat.

Currently, doctors use prostate specific antigen, Gleason grade and a rectal exam, but the predictive value of those three tests is inadequate for predicting what cancers will spread. Conventional imaging methods used for clinical staging in prostate cancer are inadequate to detect small but clinically significant lymph node metastases.

When researchers added endoglin levels to their usual methods of prediction, the accuracy improved from 89.4 percent without endoglin to 97.8 percent. Blood levels of endoglin may allow doctors to predict the risk of cancer spread at an earlier stage and with higher accuracy than currently available methods.

Despite strides in the management of prostate cancer, approximately 25 percent to 30 percent fail primary curative treatment such as radical prostatectomy and radiotherapy. This is often due to spread of cancer cells beyond the original tumor site.

Use of plasma endoglin could help identify patients at risk for lymph nodes metastasis who should undergo pelvic lymphadenectomy. In addition, it may spare patients at low risk of lymph node metastasis the potential morbidity of an unnecessary lymphadenectomy, according to Shariat.

(Agencies via Xinhua News Agency February 28, 2008)