Under Diagnosis And Over Diagnosis Of Prostate Cancer

Main Category: Prostate / Prostate Cancer
Also Included In: Urology / Nephrology;  Men's health;  Cancer / Oncology
Article Date: 15 Jul 2007 - 0:00 PDT

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UroToday.com- According to reports from the US and Europe it is more common that prostate cancer (CaP) is under diagnosed than over diagnosed. Both studies appear in the July 2007 issue of the Journal of Urology.

Dr. Graif and the group of Dr. William Catalona evaluated 2,126 men with stage T1c CaP who were treated with radical prostatectomy (RP) during three time periods; era 1 1989-1995, era 2 1995-2001, and era 3 2001-2005. In era 1 a PSA of 4.0ng/ml was used as the indication for quadrant biopsy but in era 2 a PSA threshold of 2.5ng/ml resulted in a biopsy of at least 6 cores. Era 3 was a referral group of 740 men with stage T1c CaP.

Over diagnosis was defined as tumor volume <0.5cc, Gleason score <7, organ confined CaP, and clear surgical margins. Under diagnosis was defined as non-organ confined CaP, to include extracapsular extension, seminal vesicle invasion, positive surgical margins, or lymph node metastases. Calculations were also made including or excluding surgical margins status when it was the only criteria met.

Between 1989 and 2005 27% of men met the criteria of under diagnosis and 5% met the criteria for over diagnosis. The 5- year progression-free survival for men with under diagnosis was 79% but decreased to 74% when the sole criterion of a positive surgical margin was excluded. The 5- year progression-free survival for men who did not meet the criteria for under diagnosis was 92%. The 5- year progression-free survival for men with over diagnosis criterion was 100%. Over diagnosis was more common in men younger than 55 years old. Lowering the PSA threshold for biopsy from 4.0ng/ml to 2.5ng/ml resulted in a 4% decrease in under diagnosis (30% to 2%) and a 7% increase in 5-year PFS (85% to 92%). This also increased the overall rate of over diagnosis by 5.8%. Among patients with a PSA 2.5-4.0ng/ml, 19% had under diagnosed CaP compared to 33% who had a biopsy for a PSA >4.0ng/ml. The overall study likelihood of over diagnosis was 5% (1.3%-7.1%) and the under diagnosis range was 25%-30%.

In a study from Dr. Pelzer and collaborators in Austria and Italy, there were similar conclusions. The researchers used a database of 680 men with CaP and PSA levels 2.0-10.0ng/ml who had RP between 1996 and 2005. The patients were stratified into low PSA (2.0-3.9ng/ml) and high PSA levels (4.0-10.0ng/ml. Digital rectal exam was not part of the screening process.

Over diagnosis was defined as Gleason score <7, stage pT2a disease and negative surgical margins. Under diagnosis was defined as >stage pT3 disease, or positive surgical margins.

Over diagnosis was identified in 19.7% of the low PSA group and 16.5% of the high PSA group. Under diagnosis was found in 18.9% of the low PSA group and 36.7% of the high PSA group. There was a statistical difference in the amount of under diagnosis between the low and high PSA groups. The combined group over diagnosis rate was 17.6%, and the under diagnosis rate was 30.3%. In a subset of 69 men having tumor volume available, there were only 8.7% meeting the criteria of insignificant disease.

As opposed to epidemiology reports, these database studies suggest that over diagnosis is of lower frequency and under diagnosis is a greater likelihood in the assessment of newly diagnosed CaP.

1. Graif T, Loeb S, Roehl KA, Gashti SN, Griffin C, Yu X, Catalona WJ

J Urol. 178(1):88-92, July 2007
doi:10.1016/j.juro.2007.03.017

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

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