Cancer Research Lab

In a small minority of patients, prostate cancer may progress despite undetectable or low serum levels of prostate specific antigen (PSA), according to Houston-based researchers.

In the January 15th issue of Cancer, Dr. Dan Leibovici and colleagues at the University of Texas MD Anderson Cancer note that PSA level after definitive treatment for prostate cancer is a powerful predictor of outcome. However, this is not invariably the case.

To investigate further, the researchers examined data on 4145 prostate cancer patients who were treated at their institution over a 5-year period.

Of this group, 46 patients were identified who had progression to metastatic disease detected with concomitant PSA levels of 2 ng/mL or less. Undetectable PSA levels were seen in 10 patients, including 3 who had not received treatment with hormones. Eight of these patients had small cell carcinoma.

Bone was the most common metastasis site. Such progression was seen in 35 patients. Seven patients had liver metastasis. Other sites included the lungs and brain.

Common features in these patients were aggressive and locally advanced cancer. In all, 85% of patients had a Gleason score of 7 or more, 63% had clinical T3 or T4 tumors and 41% had pretreatment PSA levels beyond 10 mg/mL. Overall, 31 patients (67%) were asymptomatic and metastasis was detected only because of routine imaging studies.

Dr. Leibovici said that “this uncommon progression pattern was observed in patients who had been diagnosed with high Gleason score on the initial biopsy or who had atypical histological forms — ductal prostate cancer or small cell cancer.”

Dr. Leibovici, who is currently at Assaf Harofeh Medical Center, Zerifin, Israel concluded that “in these patients, following the PSA as a single marker may be insufficient, and periodical imaging studies may be considered.”