Technical refinements of transrectal ultrasound-guided prostate biopsy in prostate cancer detection

ABSTRACT

Rationale In the Philippine setting, prostate cancer detection using sextant biopsy techniques yielded result ranging from 6-10 percent. However, with the introduction of the 12 core systematic biopsy technique, the cancer detection increased to 23 percent. The yield is still inferior compared to foreign counterpart and a deeper reassessment of the biopsy technique may prove otherwiseObjective: This study aims to evaluate cancer detection using a technical refinement wherein an ultrasound machine is used to visualize the prostate gland both in sagittal and longitudinal views, directing the biopsies more laterally to better sample regions of the peripheral zone using the marker lineMethods: This is a prospective cohort study of 68 consecutive males who underwent prostate biopsy from two tertiary hospitals performed by one consultant from January to September 2004. The indications for prostate biopsy included an elevation of serum PSA and/or an abnormal digital rectal examination. However, due to higher likelihood of prostate cancer in men with higher PSA, patients with PSA above 20 ng/ml were excluded from this study. The ultrasound machine used in Group A was ACUSON while that in group B used Bruel Kjaer 5001. All patients underwent a systematic 12 core biopsy techniqueResults: A total of 68 male patients with a mean age of 66.11 +/- 8.09 years, who underwent transrectal ultrasound guided prostate biopsy using the twelve core protocol from January to September 2004 were included. Twenty-eight (28) patients were included in group A and 40 were in group B. The pre-biopsy PSA level taken showed a mean of 9.55 +/- 3.03. The mean prostate gland volume on transrectal ultrasound was 39.67 +/- 13.6 and 39.67 +/- 16.9 for group A and B, respectively. The overall cancer detection rate from the total study population was 41.3 percent. Detection rate of the two populations were compared using the Wilcoxon Signed Rank Test and the Mc Nemars Test. The detection rate for group A was 21 percent while the detection rate for group B using the technical modification was 50 percent. There was a significant difference in cancer detection between the two populations at z= 2.53, p=0.01 using Wilcoxon Signed Rank Test and at p=0.02 in Mc Nemars test. Reliability analysis was also done to determine differences in the detection rates of the tests done in the two different institutions. Friedmans chi square, x2 was 14.8 at p=0.002, which means that the detection rates between the two institution was significantly differentConclusion: The prostate biopsy technique of using biplanar transrectal probe that allows confirmation of the needle tract in the transverse view before doing the biopsy in the sagittal view of the prostate increased the yield of prostate cancer detection to 50 percent. The conventional 12 core biopsy technique still maintained a 21 percent detection, which is not different from previous reports from the same institution. (Author)