UroToday.com - In the May 2009 issue of the Journal of Urology, Dr. Christina Ching and collaborators from the Cleveland Clinic report that the end-fire transrectal ultrasound (TRUS) probe improves biopsy detection rate of prostate cancer (CaP) compared to the side-fire probe.

Between 2000 and 2008, 2,674 patients underwent prostate biopsy with one of the two types of probes. The analysis is a non-randomized, observational study. The end-fire probe group had a lower mean PSA (7.6 vs. 9.6ng/ml), larger percentage with an abnormal DRE (9.9% vs. 5.5%), smaller prostates (42.5 vs. 44cc), and greater number of hyopechoic lesions (5.2% vs. 1.7%). Accounting for the percent of cases with hyopechoic findings that were positive for cancer revealed that this was not statistically significant between the two groups.

The overall CaP detection rate in the end-fire group was 45.8% compared to 38.5% in the side-fire group. This was statistically significant regardless of the number of biopsy cores taken. Detection rates differed in the PSA ranges 4-10ng/ml and >10ng/ml. When patients were evaluated who had only 8 to 12 cores sampling performed, detection rates in the end-fire and side-fire groups were 45.4% and 38.1%, respectively. This was not significant if >20 cores were performed. In multivariable analysis, smaller prostate volume, older patient age, higher PSA and hyopechoic findings were independent predictors for the detection of CaP. The number of biopsy cores sampled was not significant in multivariable analysis.

The investigators suggest that the side-fire probe is limited to a biopsy trajectory in a relatively longitudinal axis (oriented primarily along the apex to base axis), while the end-fire probe enables biopsy cores to be taken in a more transverse orientation along the anteroposterior axis. The authors acknowledge that another study had previously shown no difference, thus a prospective randomized trial would need to be performed for a definitive answer.

Ching CB, Moussa AS, Li J, Lane BR, Zippe C, Jones JS
J Urol. 2009 May;181(5):2077-82
doi:10.1016/j.juro.2009.01.035

Written by UroToday.com Contributing Editor Christopher P. Evans, MD, FACS

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