PSA as a screening tool for prostate cancer: Lessons learn from the past
Post By: Dr Ashish Kumar Saini, MS, MCh(Urology, Gold Medalist, AIIMS),DNB Director and Head, Urology
PSA (Prostate Specific Antigen) was used widely in the west for diagnosing cancer prostate where by the rule of thumb anyone with either an abnormal rectal examination of prostate or a PSA > 4 was subjected to biopsy. This was presumed because of the fact that the probability of finding cancer increases as the PSA increases. A PSA of 0-2 has a 1% probability of picking a prostate cancer while a PSA between 4-10 or more than 10 increases this probability 25 % to 50% respectively. These were some random conclusions based on poor data. The data from prostate cancer prevention trial (> 10000 men) suggest that 15% of patients with PSA less than 4 were found to have prostate cancer and 15% were high grade.
Surprisingly it was found that potentially incurable cancer was present in patients with normal PSA. So the point is what to do? Is PSA prostate specific or suggestive?
The answer is simple do you take aspirin just because your cholesterol is high? Probably no? Rather one sees other risk factor like lifestyle, family history. A similar analogy is found with treatment of other cancer (breast,oesophagus,colon) where the risk-based approach is followed to diagnose and treat. Similarly in these patients we need to follow various parameters like age, ethnicity(African Americans), prior family history, abnormal digital rectal examination, prior negative biopsy and PSA velocity to reach to a sound conclusion. So to conclude no PSA is normal PSA. One has to follow a risk-based algorithm taking into account above mentioned parameters so as to differentiate a insignificant cancer from a Significant one. Dr. Ashish Saini is counted among best Urologist in Delhi who uses PSA technique to diagnose prostate cancer