Parameters of perineural invasion in radical prostatectomy specimens lack prognostic significance

Abstract

The prognostic significance of perineural invasion by prostate cancer is debated. We have evaluated the association between biochemical failure and measurements of perineural invasion in radical prostatectomy specimens. Perineural invasion was identified in sections using S-100 protein immunostaining. For nerves showing invasion, the involved nerve closest to the edge of the prostate and to the surgical excision margin, as well as the diameter of these nerves, the largest nerve showing perineural invasion and its proximity to the excision margin, and the percentage of nerves showing perineural invasion up to 1.75 mm from the excision margin was determined and tested against time to prostate-specific antigen failure, along with preoperative prostate-specific antigen levels, highest Gleason primary grade, Gleason score and TNM T category. Perineural invasion was present in 90% of cases, with extraprostatic perineural invasion in 25% of tumors. Diameter of nerves showing perineural invasion ranged from 11 to 680 lm and the shortest distance to the surgical excision margin ranged from 33 to 2.57 mm. Perineural invasion density ranged from 6 to 96%. Gleason scores were six in 58 cases, seven in 43 cases, eight in three cases and nine in one case. Clinical T categories were T1c in 75 cases, T2a in 22 cases, T2b in five cases, T2c in two cases, T3 in one case. During a follow-up period of 11 to 55 months (median 26 months), 27 patients showed prostate-specific antigen failure. On univariate analysis only presence of extraprostatic perineural invasion, among parameters of perineural invasion, showed a weak correlation with outcome, while on multivariate analysis this lost significance and preoperative prostatespecific antigen levels, Gleason score and excision margin status were independently associated with biochemical failure. We conclude that the investigated parameters of perineural invasion do not predict prostate-specific antigen recurrence in radical prostatectomy specimens.

Prognostic Role of Perineural Invasion in 239 Consecutive Patients with Pathologically Organ-Confined Prostate Cancer

“…When interpreting data from the literature, a possible variable is the different proportion of nerves involved. Indeed, the detection rate of PNI ranges from 32 to 84% [16]. The discrepancy may depend on differences in the patient population, the prostatectomy technique adopted and the pathologic analysis of the specimens.…”

“…In particular, the presence of PNI has been shown either to correlate or to have no association with PSA failure after RRP. In those studies in which PNI had a prognostic significance at univariate analysis, its significance was often lost when modeled with various clinicopathological parameters, such as preoperative PSA, Gleason score and pathologic stage at multivariate analysis [7,9,10,16].…”

Biopsy sampling and histopathological markers for diagnosis of prostate cancer

“…Based on a systematic review, it has been argued that the importance of PNI may have been underestimated due to considerable variability in study design, implementation and reporting [87]. The association between detailed parameters of PNI (closest distance to the edge of the prostate, closest distance to the peripheral zone resection margin, cross-sectional diameter of the nerve and PNI density) and biochemical failure has been assessed in 105 radical prostatectomy specimens and compared with established prognostic parameters [88]. Of the tested PNI parameters, only the presence of PNI beyond the edge of the prostate showed a significant, although marginal, association (p = 0.047) with biochemical failure, which was lost on multivariate analysis, probably due to the already poor prognosis associated with extraprostatic tumor spread [88].…”

Does perineural invasion in a radical prostatectomy specimen predict biochemical recurrence in men with prostate cancer?

“…1 It is evident on histological examination of radical prostatectomy (RP) specimens in a significant proportion of cases. 2,3 Theoretically the presence of PNI on RP specimens may correlate with risk of disease progression. However, the prognostic significance of this is controversial and evidence in this area has been derived from relatively small cohort studies.…”