Impact of prostatic anterior fat pads with lymph node staging in prostate cancer

Background: Several reports have revealed the presence of lymph nodes in the prostatic anterior fat pad (PAFP). To date, no study has described the characteristics of Taiwanese patients harboring PAFP lymph nodes with metastatic prostate cancer involvement. Method: Between December 2006 and May 2015, a total of 849 consecutive patients underwent robot-assisted laparoscopic radical prostatectomy with PAFP dissection. Pathological examination of the dissected PAFP was conducted to assess the presence of lymphoid tissue and prostate cancer involvement. Results: Of the 849 patients, 76 (9.0%) had 1-3 PAFP lymph nodes. Moreover, 11 (1.3%) of the 76 patients had positive lymph node metastases of prostate cancer in the PAFP; 5 (0.6%) of the 11 patients, who had negative pelvic lymph node involvement, were upstaged because of positive metastases in PAFP lymph nodes. Among the 76 patients having PAFP lymph nodes, metastatic lymph nodes were associated with the clinical T stage, preoperative Gleason score, pathological T stage, and pathological N stage (p < 0.001). Patients with pathological seminal vesicle invasion and a higher surgical Gleason score also exhibited PAFP lymph node metastases (p < 0.005). Conclusion: Our data show that 9.0% of patients had PAFP lymph nodes and that 1.3% had prostate cancer metastases. Additionally, 0.6% of patients were upstaged because of positive metastases in PAFP lymph nodes. Because of the pathological analysis of the PAFP, a few patients were upstaged. Thus, routine pathological analysis of the PAFP should only be conducted for those with higher preoperative prostate-specific antigen, higher Gleason score, and advanced T stage observations.