Pathologic Analysis of the Prostatic Anterior Fat Pad at the time of Radical Prostatectomy: Insights from a Prospective Series

To assess factors associated with lymphatic drainage and lymph node metastasis to the prostatic anterior fat pad (PAFP) in men with prostate cancer and the utility of routine PAFP analysis at the time of radical prostatectomy (RP).

Our institution began to prospectively collect PAFP tissue in 2010. The PAFP was removed at the time of RP and sent as a pathologic specimen separate from the pelvic LNs and prostate. Consecutive RPs performed at our institution in which the PAFP was removed were reviewed to determine the rate of LNs in the PAFP, the rate of metastatic LNs in the PAFP, and the association of metastatic PAFP LN with clinical and pathologic features. The impact on biochemical recurrence was assessed with a Cox's proportional hazard model.

In total, 2,413 AFP specimens were available for analysis. LNs were found in the AFP in 255(10.6%) cases and metastatic LNs to the PAFP were found in 14 (0.6%) cases. Metastatic PAFP LNs were associated with anterior tumors in 11 (78.6%) cases (p = 0.01), and were present only in pre-operative D'Amico intermediate- (n=6, 42.8%) and high- (n=8, 57.1%) risk patients (p < 0.001). Metastatic PAFP LNs were associated with extraprostatic disease in 13 (92.8%) of cases, though concomitant pelvic LN involvement was present in only 4 (28.6%) cases. With a mean follow up of 1.5 years, 3 (21.4%) patients with metastatic PAFP LN experienced BCR. Positive LN involvement in either the pelvic LN or PAFP had worse BCR than LN negative patients (p < 0.0001); however, there was no difference in BCR between patients with positive pelvic LN and positive PAFP LN (p=0.5).

Metastatic PAFP LNs are rare and always occur in the presence of other adverse pathologic features. The routine pathologic analysis of PAFP as a separate specimen, especially in low-risk disease, may not be warranted. This article is protected by copyright. All rights reserved.

BJU international. 2016 Sep 09 [Epub ahead of print]

Mark W Ball, Kelly T Harris, Zeyad Schwen, Jeffrey K Mullins, Misop Han, Patrick C Walsh, Alan W Partin, Jonathan I Epstein

Departments of Urology, The Johns Hopkins Medical Institutions. ., Departments of Urology, The Johns Hopkins Medical Institutions.