NEW YORK (Reuters Health) - Complete loss of PTEN expression may be an early marker of prostate cancer metastasis risk, according to a report in the March 15th International Journal of Cancer.

"Additional large scale studies are certainly necessary before systematic routine screening of PTEN expression at first time diagnosis of prostate cancer should be recommended," Dr. Nelly Kieffer, from Universite du Luxembourg, told Reuters Health.

Dr. Kieffer and colleagues investigated PTEN expression in 42 prostate cancer patients with lymph node metastasis and 127 patients who underwent first time prostate biopsy and were diagnosed with prostate adenocarcinoma.

Cells of normal prostate epithelium in culture stained positive for PTEN, the authors report, whereas prostate cancer cells were negative.

Among patients with lymph node metastasis, the patient with the most aggressive cancer phenotype had complete loss of PTEN expression, whereas other patients had weak or positive staining for PTEN.

There was no correlation between loss of PTEN expression and Gleason score, PSA level, or age in the patients newly diagnosed with prostate cancer, the results indicate.

Only PTEN-negative cancer cells were found in the satellite lymph node of patients with metastasis, the researchers note, which "suggests that PTEN-negative adenocarcinoma cells represent the subpopulation of cancer cells with the most invasive phenotype."

"Taken together," the investigators conclude, "our data suggest that loss of PTEN expression, rather than upregulated EGF/IGF1 receptor expression is responsible for increased p-Akt expression in neoplastic prostate cells. These data thus emphasize the importance of routinely assessing the status of the PTEN gene and its expression during prostate cancer progression."

"Our approach is now to perform PTEN expression analysis at first time diagnosis of those prostate cancer patients under the age of 65 with a low Gleason score and a low PSA level (the typical 'wait and see' patients)," Dr. Kieffer said. "In this cohort, the PTEN negative patients will be considered as potential candidates to develop metastasis and the 'wait and see' therapeutic approach will be replaced by a more aggressive approach."