Is pre-biopsy serum prostate specific antigen retesting always justified? A study of the influence of individual and analytical factors on decision making for biopsy referral.

Abstract Background and aims We investigated factors influencing pre-biopsy prostate-specific antigen (PSA) retesting as recommended by clinical guidelines. Materials and methods 333 patients screened for prostate cancer (PCa) repeated PSA (Roche Cobas systems) after a median of 3.9 months, before performing biopsy. Multiple regression models were used to assess effects of patients’ characteristics on PSA results and changes over time. Results PCa [n=132 (40.7%)] and cancer-free [n=192 (59.3%)] patients had similar rate of PSA positive results at baseline (84.8% vs. 83.9%, P=0.931). Their rate of reversion to normal PSA after retesting was negligible (0.9% in PCa and 3.7% in PCa-free patients, P=0.286). 31.1% of PCa and 31.3% of cancer-free patients (P=0.426) showed a significant PSA increase after retesting. Age was a confounder since not only PSA increased in older PCa patients, but it was also related to PCa histological grade, in turn associated to PSA increase. In PCa-free patients, glandular inflammation, present in 1/3 of subjects, was also associated to higher PSA concentrations. Conclusion When obtained with the same immunoassay under controlled analytical conditions, a PSA positive result is confirmed after retesting in the great majority of screened patients. Neither analytical factors nor intraindividual variability appeared to justify PSA retesting before biopsy referral.