April 16, 2007

The Prognostic Significance Of Perineural Invasion In Prostatic Cancer Biopsies

UroToday.com- Whether perineural invasion (PNI) identified in prostate cancer (CaP) biopsies is associated with disease recurrence is unclear from the literature. In an attempt to resolve this uncertainty, a systematic review was performed by Dr. Patricia Hamden and colleagues in the UK and published in the online edition of Cancer. What they found was that variable study design, execution and reporting excluded a definitive meta-analysis, but evidence suggests that PNI in biopsies was a significant prognostic indicator.

The authors' strategy used 128 search terms to identify articles published between 1990 and 2005. A total of 41,295 titles were reviewed by at least 2 reviewers and 128 articles identified for close evaluation. Ultimately, 10 surgical and 11 radiotherapy articles on PNI in biopsies as it related to patient outcomes were used in the report. Data items specific to biopsy PNI in CaP included biopsy procedure (amount of cores, number of nerves present and identification of PNI), histological slide preparation and pathological interpretation (consistency of identification, inclusion of information if no nerves were present).

No study reported on all data items and incomplete items ranged from 18% to 61% with a median of 39%. Exclusion criteria were variable, but included a history of prior treatment, unavailability of biopsies for review or the failure to obtain at least 4 biopsies. Only 1 surgical and 1 radiotherapy article was prospective. In surgical patients details on nerve sparing was generally lacking. In 12 studies, biopsies were reviewed for the presence of PNI and in 1 study 60% of biopsies were reviewed for this. In 5 studies the slides were not reviewed but the diagnosis was taken from the original report and in 3 articles the information was not provided. Only 2 articles reported blinded pathologic review. Individual patient data was sufficient in 5 articles to permit reanalysis.

The proportion of patients with PNI varied between 7% and 12% (median 9%) when the diagnosis was obtained form the original report and between 7% and 43% (median 23%) when slides were reviewed to identify PNI. Most studies had short (<6 months) of clinical follow-up. Overall, 6 of 10 surgical and 5 of 11 radiotherapy studies identified PNI as a prognostic factor in univariate analysis. Surgical articles that included a larger number of patients with less patient exclusion reported that PNI was independently prognostic in multivariate analysis with PSA and biopsy Gleason score. More than two-thirds of external radiotherapy studies but no brachytherapy study showed prognostic significance for perineural invasion. The highest incidence of PNI was found in locally-advanced disease.

Surprising to the authors were that none of the articles considered that the presence of nerves in the biopsies was a prerequisite for patient inclusion and no article provided data on the reproducibility of the PNI diagnosis. The authors conclude that the importance of PNI was likely to have been underestimated by the inclusion of uninformative test results (biopsies with no nerves in the specimens) and that despite this, the majority of studies including those performing multivariate analysis found prognostic significance to PNI. The weight of evidence supports PNI as of prognostic significance.

Patricia Harnden, Michael D. Shelley, Hayley Clements, Bernadette Coles, R. Sandy Tyndale-Biscoe, Brian Naylor, Malcolm D. Mason

Cancer 2006
Published Online: 22 Nov 2006

DOI: 10.1002/cncr.22388

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

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