Biopsy Schemes With The Fewest Cores For Detecting 95% Of The Prostate Cancers Detected By A 24-Core Biopsy

Main Category: Prostate / Prostate Cancer
Also Included In: Urology / Nephrology
Article Date: 01 Dec 2009 - 4:00 PDT

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UroToday.com - Transrectal ultrasound with prostate biopsy (TRUS/Bx) remains the method for detection of prostate cancer (CaP) in men with an elevated PSA or abnormal digital rectal examination. It is clear that the methodology of sampling will influence the detection rate of CaP. In the online edition of European Urology, Dr. Vincenzo Scattoni and colleagues reported on the optimal TRUS/Bx schemas to detect CaP using 24 biopsy cores or less.

From 2005 to 2008, a 24 core saturation TRUS/Bx was performed under local anesthesia in 617 consecutive men. Indications were either a PSA between 2.5 and 4.0ng/ml with an abnormal DRE or a PSA >4.0ng/ml. An end-fire probe was used with standard local nerve block using lidocaine. The 24-core biopsy schema is shown in the manuscript and includes extensive sextant, lateral, sub-capsular biopsies in addition to 2 anterior and 2 posterior transition zone cores. All cores were individually inked and pathology was performed by one uropathologist.

For statistical analysis, the standard Stamey detection rate with six cores, was used as a baseline. One single core per each side of the prostate was added and the CaP detection rate calculated. A total of 255 possible combinations were derived. High grade PIN and ASAP were not included in the definition of a positive prostate biopsy. The cohort was also stratified into four groups based upon CaP detection risks:

1. DRE negative, prostate volume (PV) <60cc, and age <65 years;
2. DRE negative, PV<60cc, and age >65 years;
3. DRE negative, PV>60cc; and;
4. DRE positive.

CaP was detected in 289 of 617 patients (46.8%). In a cross-validation model, increasing the number of cores increased the CaP detection rate. The following detection rates were found; with 8 cores 36.3%, with 10 cores 38.7%, with 12 cores 40.6%, with 16 cores 43.5%, with 20 cores 45.6%, and with 24 cores 46.8%. The investigators then determined the best combination of sampling sites that detected >95% of the CaPs with the minimum number of prostate biopsy cores. For group 1, a combination of 16 cores was best, for groups 2 and 3 two different combinations of 14 cores schemas were best and for group 4 (men with a positive DRE) a 10 cores biopsy was best. The details of the cores locations are nicely illustrated in the paper.

This study suggests that both the number and location of prostate biopsy cores influence the CaP detection rate. However, the true diagnostic accuracy is not obtainable as all men do not undergo radical prostatectomy. Furthermore, whether the cancers detected are clinically significant is unknown. The ability to accurately place the biopsy needle in the exact locations is also unknown, but new technologies that use computer-assisted placement may impact this.

Scattoni V, Raber M, Abdollah F, Roscigno M, Dehò F, Angiolilli D, Maccagnano C, Gallina A, Capitanio U, Freschi M, Doglioni C, Rigatti P, Montorsi F
Eur Urol. 2009 Aug 19. (Epub ahead of print)
10.1016/j.eururo.2009.08.011

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