Screening For Prostate Cancer At Low PSA Range: The Impact Of Digital Rectal Examination On Tumor Incidence And Tumor Characteristics

UroToday.com - For prostate cancer (CaP) screening, PSA and digital rectal examination (DRE) potentially detect different grade and stage tumors. DRE may detect more clinically significant, high-grade lesions compared to PSA. On the other hand, PSA may also capture these tumors, suggesting DRE may add little to the screening process. Dr. Gosselaar and colleagues from Erasmus University Medical Center and Mount Sinai Hospital, Toronto, Canada evaluated this hypothesis and published their report in the Early View version of The Prostate.

The researchers studied two groups who participated in the Rotterdam CaP screening study. All participants initially presented with PSA levels between 2.0 and 3.9ng/ml. Group 1 consisted of men biopsied for a suspicious DRE (N=1,877). Group 2 men were all offered biopsy, regardless of the DRE result (N=801). For group 1, data was used from the first screening round with a screening protocol based on both the PSA value and DRE result between 1993 and 1997. Group 2 data was from a side-study performed in the second screening round and biopsy was recommended for a PSA of 2.0ng/ml or greater. Primary study outcomes were cancer detection rate (CDR), positive predictive value (PPV) and tumor characteristics.

Of the 1,877 men with evaluable data in group 1 mean age was 65 years, mean PSA was 2.8ng/ml and mean prostatic volume was 40cc. An abnormal DRE was found in 253 men (13.5%) and 236 of these men agreed to a biopsy. CaP was found in 49 men for a PPV of 20.8% and a CDR of 2.6%. The translated into the need to biopsy 5 men to detect 1 CaP and 10 biopsies were needed to detect 1 CaP of Gleason score >7. Gleason score >7 tumors were found by DRE in 47%. Organ confinement was found in 77.5% of these patients.

In group 2 mean age was 67 years, mean PSA was 2.7ng/ml and mean prostatic volume was 41cc. Of the 664 men who ultimately proceeded to biopsy, 120 had CaP detected for a PPV of 18% and a CDR of 15%. To detect 1 CaP it was necessary to biopsy 6 men and 37 biopsies were needed to detect 1 CaP of Gleason score >7. Of the 39 men who proceeded to surgery, organ confinement was found in 86%.

When considering the detection of organ confined CaP for the 2 groups, DRE-based screening had a detection rate of 2.0% and PSA screening had a detection rate of 14.5%. Detection of Gleason score >7 tumors was 1.2% for group 1 and 2.3% for group 2. To find Gleason score >7 tumors, 16 and 31 biopsies were required in groups 1 and 2, respectively.

These data suggest that DRE more selectively detects high-grade CaP, but will miss many as well. PSA outperforms DRE at a cost of more biopsies performed.

Claartje Gosselaar, Monique J. Roobol, Stijn Roemeling, Theo H. van der Kwast, Fritz H. Schrцder

Prostate 2006: Early View

Reviewed by UroToday.com Contributing Editor Christopher P. Evans, M.D.

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