New Blood Marker May Predict Prostate Cancer Spread

Researchers have reported finding a blood biomarker that enables close to 98% 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, a journal of the American Association for Cancer Research. 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.

"For prostate cancer, we have hit the limit of our ability to classify risk in these patients before initial surgery. We currently 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 modalities used for clinical staging in prostate cancer are inadequate to detect small but clinically significant lymph node metastases," said study author Shahrokh F. Shariat, md, chief urology resident at the University of Texas Southwestern Medical Center.

"Although it is recognized that pelvic lymphadenectomy can provide important staging and prognostic information, it is still not clear in whom this procedure should be done. Doing pelvic lymphadenectomy on all patients is not universally practiced, as this procedure could be time-consuming and is not without morbidity. As such, it would be of tremendous benefit to have an accurate blood marker that identifies patients in whom pelvic lymphadenectomy should be done," said coauthor Claus G. Roehrborn, md, professor and chairman of urology at the University of Texas Southwestern Medical Center.

Key Findings

Shariat and his colleagues observed 425 patients who had undergone surgery to remove their prostates and associated pelvic lymph nodes. Researchers measured the levels of plasma endoglin using a commercially available blood test. Higher plasma endoglin levels were associated with an increased risk of cancer spread to the lymph nodes. Each 1-ng/mL increase of plasma endoglin increased the risk for cancer spread into the lymph nodes by 17%. When researchers added endoglin levels to their usual methods of prediction, the accuracy improved from 89.4% without endoglin to 97.8%. Blood endoglin levels may allow doctors to predict the risk of cancer spread at an earlier stage and with higher accuracy than currently available methods.