Population-based screening for prostate cancer by measuring free and total serum prostate-specific antigen in Iran

To evaluate the natural background of prostate cancer in Iran a large population-based study of screening using total prostate-specific antigen (tPSA) and per cent free PSA (fPSA) as the initial test was performed.

For 9 years (1996 to 2004) in Tehran, Iran, 3670 Iranian men older than 40 years were mass checked by PSA-based screening. They were invited to have a digital rectal examination (DRE), serum PSA assay and transrectal ultrasonography (TRUS)-guided sextant prostate biopsy to see if the DRE was clinically suspicious of malignancy, the serum PSA was > or =2.1 ng/ml or free-to-total PSA (f/tPSA) ratio < or=15%.

In 433 (11.8%) of screened males, tPSA levels exceeded the cut-off value of > or =2.1 ng/ml and 128 prostate cancers were diagnosed [positive predictive value (PPV) 29.6%] corresponding to an overall detection rate of 3.5%. Altogether 138 cancers were detected (detection rate 3.8%); none were stage M(1), three were stage N(+) and 4 stage T(3). A threshold tPSA of > or =2.1 ng/ml would have detected 128 cancers in 447 biopsied men (PPV 29%). There were 109 of 138 (79%) men with cancer who had an f/tPSA of < or =15%, while 152 of 305 (49.8%) with benign biopsies had a f/tPSA of < or =15%, which corresponds to a PPV of 30.8%.

PSA-based screening with low PSA cut-off values increase the detection rate of clinically significant, organ confined and potentially curable prostate cancer. Further studies are warranted in order to determine the incidence and prevalence of prostate cancer in different ethnic groups.