Perineural invasion in prostatic carcinoma treated with radical prostatectomy: the role of TR systematic biopsy.

Perineural invasion (PNI) is a morphological entity which has been known for many years, though its significance in prostatic neoplasms has only been studied recently. Therefore, we tried to assess, with the help our experience, its presence and its significance. Ninety-four patients, aged between 49 and 74 (average 65.8)--with a PSA between 2.69 and 52 ng/ml (average 11.44)--underwent RP for prostatic carcinoma; 58 patients had stage T2 and 36 had T3. 48 patients had Gleason 7 or higher, and 46 had G 6 or lower. Fifty patients (53,1%) were PNI+ and 44 (46,9%) PNI-. Between the two groups there was no significant difference as to age (1" group: average age 67 years; 2nd group: 68) and PSA (1st group: average 9.73 ng/ml, 2nd group: average 8,17) (Z 0,639). The distribution according to the stage showed that 24 patients (48%) PNI+ were T2 and 26 (52%) PNI+ T3, 34 (77.2%) PNI- T2 and 10 (22%) PNI- T3 and therefore 72,23% of the T3's were PNI+ and 41.3% of the T2's were PNI+; 34 patients (70.8%) with G>7 were PNI+ and 14 (29.16%) PNI-, 16 patients (34,78%) with G<6 were PNI+ and 30 (65.2%) PNI-. Among the PNI+ 50 patients, 36 had undergone biopsy in our hospital, and therefore we re-examined the operation tissue and found out that 16 (44%) were biopsy PNI+ while for 22 (55.5%) it was not possible to assess the PNI on the biopsy tissue. PNI is an important morphological element in the staging of prostatic cancer and is connected with the disease negative prognostic factors: in fact, it can be traced with a high frequency in stage diseases and higher Gleasons. It does not seem to be connected with PSA, above all for values between 4 and 20 ng/ml. We think that a very important element to be stressed is the fact that this condition is not always detected with biopsy (about 45%) and this does not allow, in such cases, an adequate therapy plan. Also our experience seems to confirm that, therefore, in spite of the above said limits, it is advisable to search PNI both with biopsy--in order to have a further prognostic element and therefore arrange the most suitable therapy plan--and on the surgery piece, in order to better determine the biological nature of the disease and to be able to suggest adequate integrative therapies.