UROLOGICAL SURVEY   ( Download pdf )

 

IMAGING

Use of extended pattern technique for initial prostate biopsy
Siu W, Dunn RL, Shah RB, Wei JT
Departments of Urology and Pathology, University of Michigan, Ann Arbor, Michigan, USA
J Urol. 2005; 174: 505-9

  • Purpose: An extended prostate biopsy schema has been advocated at initial prostate biopsy to decrease the rate of false-negative cancer cases. However, critics have raised concerns that this may lead to the greater detection of clinically insignificant cancers. We examined the impact of using an extended pattern schema on cancer detection and also on the finding of smaller and clinically insignificant cancer.
  • Materials and Methods: Clinical data, including patient age, race, prebiopsy prostate specific antigen (PSA), digital rectal examination, prostate volume, number of needle cores and biopsy findings were abstracted from the medical records of all patients who underwent prostate biopsy in a 5-year period. Extended pattern prostate biopsy was defined as more than 10 cores. Clinically insignificant cancer was defined as a maximal tumor dimension of 1.0 cm or less, Gleason sum 6 or less and organ confined disease at radical prostatectomy. Adjusted regression models were developed to assess the independent effects of using an extended biopsy pattern on the detection of cancer overall and on the detection of clinically insignificant cancer.
  • Results: A total of 740 men with a mean age of 62.6 years were referred for prostate biopsy. Median PSA was 5.7 ng/ml and prostate volume was 39.7 cc. The OR for detecting prostate cancer was 1.55 (95% CI 1.09 to 2.19) for the extended pattern compared with standard biopsy. Of the subset of 136 patients who underwent radical prostatectomy 12.6% had clinically insignificant cancer. However, in contrast to overall cancer detection, extended pattern prostate biopsy was not found to be associated with an increased risk of detecting smaller or clinically insignificant cancer. PSA density was the single parameter found to be independently associated with the detection of clinically insignificant cancer (95% CI 0.20 to 0.98).
  • Conclusions: Using an extended prostate biopsy pattern involving more than 10 cores increases the likelihood of detecting prostate cancer. A significant association between more needle cores at initial prostate biopsy and finding smaller and clinically insignificant cancer was not apparent.

  • Editorial Comment
    There is a worldwide tendency to perform an extended biopsy for the initial evaluation of a patient suspecting of prostate cancer. When both scheme of biopsy (sextant and extended) are performed in the same group of patients overall yield of prostate cancer detection varies from 0 to 35%. When we compare the results of both schemes in distinct group of patients the yield is still significant. In a recent review of our clinical database we had a 24.6% detection rate in a group of 2,647 patients submitted to sextant biopsy and a 39.7% detection rate in the group of 1,000 patients who underwent a 12-cores-scheme of biopsy (yield of 15.1%).We have to consider that in the last group many patients were biopsied because their PSA level was > 2.5 ng/mL. The authors reviewed the results of initial prostate biopsy performed in a group of 740 patients in which 136 patients with prostate cancer were treated by radical prostatectomy. The extended pattern prostate biopsy technique (more than 10 cores) increased the cancer detection rates when compared with the sextant scheme, without a significant increase in clinically insignificant disease. Clinically insignificant cancer was defined as cancer with maximal dimensions of 1.0 cm or less at prostatectomy (i.e. a diameter of 1.0 cm or less, corresponding to a volume of 0.5 cc or less), Gleason sum 6 or less and organ confined disease. This article brings us an important information about an intriguing phenomenon, which is related to the potential increasing in the number of clinically insignificant tumors by increasing the number of cores. Similarly to others studies the authors report that they found the lack of an association between an extended biopsy technique and the detection of smaller or clinically insignificant tumors. From a practical point of view one limitation of this study is that the authors used the surgical pathology results for define clinically insignificant cancer. It would be interesting to have this information before surgery. But this issue is also controversial since there are different criteria to predict insignificant prostate cancer on prostate needle biopsy (1): needle biopsies with prostate carcinoma in fewer than 3 cores (from a 6-core biopsy sample), absence of Gleason grade (pattern) 4 or 5, no more than 50% prostate carcinoma involvement in any of these cores, stage T1c and PSA density < 0.15 ng/mL (2) and focal carcinoma on sextant biopsy defined as < 3 mm in length in only one core, no Gleason grade (pattern) 4 or 5, and PSA density (PSAD) cut-off level of < 0.10 ng/mL (3). Other new information is related to PSAD, which was found to be the single parameter independently associated with the detection of overall cancer and clinically insignificant cancer. The authors found that at lower PSAD prostate cancer was less likely to be detected but a greater proportion of them were insignificant cancers and that PSAD greater than 0.2 was the threshold at which there was a lower likelihood of detecting insignificant cancer. Beyond PSAD greater than 0.3 all cancers detected were clinically significant. The authors state that the simple calculation of PSAD may be useful for determining whether the cancer detected by extended biopsies is potentially insignificant disease. Unfortunately, at least in our experience, the majority of patients submitted to the initial biopsy has PSAD < 0.2. This finding is even more pronounced when we biopsy patients with PSA level > 2.5 ng/mL.

References
1. Billis A: Comment on: Postma R, Vries SH, Roobol MJ, Wildhagen MF, Schroder FH, van der Kwast TH: Incidence and follow-up of patients with focal prostatic carcinoma in 2 screening rounds after an interval of 4 years. Int Braz J Urol. 2005; 31: 280-281.
2. Epstein JI, Walsh PC, Carmicahel M, Brendler CB: Pathologic and clinical findings to predict tumor extent of nonpalpable (stage T1c) prostate cancer. JAMA. 1994; 271: 368-74.
3. Bastian PJ, Mangold LA, Epstein JI, Partin AW: Characteristics of insignificant clinical T1c prostate tumors. A contemporary analysis. Cancer. 2004; 101: 2001-5.

Dr. Adilson Prando
Chief, Department of Radiology
Vera Cruz Hospital
Campinas, São Paulo, Brazil