Weight CJ et al. (2006) Perineural invasion on prostate needle biopsy does not predict biochemical failure following brachytherapy for prostate cancer. Int J Radiat Oncol Biol Phys 65: 347–350

The importance of perineural invasion (PNI) as a prognostic indicator in patients with prostate cancer is controversial and the data on the prognostic significance of PNI in those patients receiving brachytherapy are sparse. Researchers from the Cleveland Clinic Foundation, OH, USA have now reported that PNI does not predict biochemical failure in patients with prostate cancer treated with brachytherapy.

In this matched-pair analysis, all patients received brachytherapy of 144 Gy to the prostate. Cases (biochemical failure) were matched with controls (no biochemical failure) for clinical stage, Gleason score, prostate-specific antigen level, age, race, and androgen deprivation status. A total of 56 pairs were available for analysis. Median follow-up time between cases and controls was comparable (58.5 and 53.5 months, respectively). The number of patients with PNI did not differ significantly between the two groups. Although there was a slight trend towards increased biochemical failure in patients with PNI, Kaplan-Meier analysis revealed that the difference between PNI-positive and PNI-negative patients was not statistically significant (P = 0.4014).

Although this study was limited by sample size, the authors conclude that the data are consistent with other reports in the literature that PNI does not have prognostic value in patients with prostate cancer. They suggest that post-therapy external beam radiation for patients with PNI is, therefore, unnecessary.