[1048] Perineural Invasion (PNI) in Prostate Cancer Patients Who Are Potential Candidates for Active Surveillance: A Validation Study

Cheng Wang, Jianguo Zhang, Asli Yilmaz, Tarek A Bismar, Kiril Trpkov. Calgary Laboratory Services and University of Calgary, Calgary, AB, Canada

Background: One study recently showed that the presence of PNI on positive needle biopsy in patients considered for active surveillance should not represent an exclusion criterion (J Urol 2011;186:470-3). We sought to validate this finding in a large cohort of patients who fulfilled the Epstein biopsy criteria for active surveillance, but proceeded to radical prostatectomy.
Design: We retrieved from our institutional prostate cancer database the biopsy, prostatectomy and the clinical data of 845 patients who met the Epstein criteria (biopsy Gleason score ≤6 (no pattern 4), 2 or fewer positive cores and ≤50% involvement of any positive core). All patients had standard ten-core biopsy and radical prostatectomy (specimens completely embedded) in our institution between 07/2000 and 06/2010. We compared the clinical, biopsy and prostatectomy data in patients with and without PNI on needle biopsy. Means were compared between the PNI and no PNI groups using the Student's t-test for continuous variables. For categorical variables, proportions were compared between the groups using chi-square or Fisher's exact test. All tests were two-sided, and the P values were considered significant at less than 0.05.
Results: PNI was present in 63 (7.4%) biopsies. Preoperative and prostatectomy findings are shown in Tables 1 and 2.

Table 1. Clinical and biopsy findings in patients with and without PNI on biopsy

	PNI (n=63)	no PNI (n=782)	P-value
Age (years), Mean	60.3	59.4	0.33
PSA ng/ml, Mean	6.2	6.5	0.57
Gland vol. cc, Mean	45	46.1	0.72
2-core positive (%)	57.1	36.8	0.001
Total % cancer on biopsy	2.5	1.8	<0.001

Table 2. Prostatectomy findings in patients with and without PNI on biopsy

	PNI (n=63)	no PNI (n=782)	P-value
Organ confined (%)	95.2	96.4	0.50
Positive margins (%)	20.6	16.4	0.39
TU vol. (gland %)	8.2	7.3	0.36
Gleason ≤6 (%)<<	57.1	66.8	0.13*
Gleason 3+4 (%)	39.7	29
Gleason 4+3 (%)	1.6	3.1
Gleason≥8 (%)	1.6	1.1

*Gleason ≤6 vs Gleason>6

No significant differences were found between the PNI and no PNI groups when separate analysis was performed for the 1-core and 2-core positive patients.
Conclusions: We confirm that the presence of PNI on biopsy should not be used to exclude patients from active surveillance if the Epstein biopsy criteria are met. Although patients with PNI presented more frequently with 2-core positive biopsies and had higher total volume of cancer on biopsy, we found no statistically significant differences in the clinical and prostatectomy findings in patients with PNI compared to patients without PNI on biopsy.
Category: Genitourinary (including renal tumors)

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 165, Wednesday Afternoon