Is it worth removing prostatic anterior fat pad to detect lymph node metastasis of prostate cancer during robotic-assisted radical prostatectomy?

Chia-Hung Chen; Hsiao-Jen Chung; Alex T L. Lin; Kuang-Kuo Chen

doi:10.4103/UROS.UROS_73_18

ORIGINAL ARTICLE

Year : 2018 | Volume : 29 | Issue : 6 | Page : 284-287

Is it worth removing prostatic anterior fat pad to detect lymph node metastasis of prostate cancer during robotic-assisted radical prostatectomy?

Chia-Hung Chen¹, Hsiao-Jen Chung², Alex T L. Lin², Kuang-Kuo Chen²
¹ Department of Urology, Taipei Veterans General Hospital, Taipei, Taiwan
² Department of Urology, Taipei Veterans General Hospital; School of Medicine, National Yang-Ming University; Shu-Tien Urological Research Center, Taipei, Taiwan

Date of Web Publication

22-Nov-2018

Correspondence Address:
Hsiao-Jen Chung
Department of Urology, Taipei Veterans General Hospital, No. 201, Section 2, Shipai Road, Taipei 11217
Taiwan

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/UROS.UROS_73_18

Abstract

Objectives: To determine the number of lymph node in prostatic anterior fat pad (PAFP) and the incidence of metastasis in lymph nodes dissected during robotic-assisted radical prostatectomy (RARP). Methods: From May 2011 to November 2015, PAFP were removed in 146 patients who underwent RARP and sent for pathological analysis to determine the number of lymph nodes and incidence of metastasis to the lymph nodes. Another 48 patients without PAFP removal were enrolled as the control group. Operative features including operative time, estimated blood loss, post-operative hospital stay, and the incidence of complications were compared between the two groups. Results: Lymph nodes within PAFP were detected in 14/146 (9.6%) patients, with metastatic lymph nodes in 2/146 (1.3%) patients. The patients with metastatic lymph nodes in the PAFP had no obturator lymph node involvement. There were no significant differences in operative features between the two groups. Conclusions: Our findings demonstrated that PAFP contain lymph nodes, and that the incidence rate of lymph node metastasis was high. There was no increase in the surgical risk when removing PAFP, and therefore we suggest that PAFP be routinely removed during RARP and then analyzed pathologically to allow for precise lymph node staging.

Keywords: Lymph node metastases, prostate cancer, prostatic anterior fat pad, robotic-assisted radical prostatectomy

How to cite this article:
Chen CH, Chung HJ, L. Lin AT, Chen KK. Is it worth removing prostatic anterior fat pad to detect lymph node metastasis of prostate cancer during robotic-assisted radical prostatectomy?. Urol Sci 2018;29:284-7

How to cite this URL:
Chen CH, Chung HJ, L. Lin AT, Chen KK. Is it worth removing prostatic anterior fat pad to detect lymph node metastasis of prostate cancer during robotic-assisted radical prostatectomy?. Urol Sci [serial online] 2018 [cited 2023 Dec 1];29:284-7. Available from: https://www.e-urol-sci.com/text.asp?2018/29/6/284/240953

Introduction

Lymph node (LN) metastasis represents an advanced stage of prostate cancer, and as such, it is a poor prognostic factor.^[1] Currently, the most effective method to detect LN metastasis is pelvic LN dissection (PLND).^[2] Extended PLND is currently the standard procedure for patients at an intermediate and high risks. Extended PLND results in a higher yield of LNs and fewer missed positive nodes, which has been reported to lead to survival benefits.^[3] The areas most commonly involved in extended PLND include the external iliac, internal iliac, and obturator nodal regions.^[4]

In robotic-assisted radical prostatectomy (RARP), removal of the fatty tissue from the anterior part of the prostate is essential to well expose the prostatic apex and junction of the bladder and prostate. Usually, this fatty tissue is not submitted for routine pathological examinations. However, a few recent studies have reported that metastatic LNs may be present in prostatic anterior fat pad (PAFP) and other fatty tissues outside of the standard dissection areas.^[5],[6]

In our institution, PAFP is removed during RARP, and it is sent for pathological examination. The purposes of this study were to (1) determine how many LNs are removed along with the PAFP dissection and (2) what is the proportion of nodes showing positive for metastasis during RARP. Demographic data and the operation-related parameters including operating time, estimated blood loss, postoperative hospital stay, and the incidence of complications were also analyzed.

Materials and Methods

From May 2011 to November 2015, totally 194 patients underwent PLND during RARP were enrolled. PAFP removal was done routinely since 2012 in our hospital. The boundaries of the PAFP dissection were superiorly the pubic arch, inferiorly the prostate, bladder neck, and endopelvic fascia, and laterally the edges of the prostate.^[7] PAFP was not removed routinely in our hospital before 2012. There were 48 patients without PAFP removal before 2012. The other 146 patients had undergone PAFP excision after 2012.

Preoperative data of the patients including age, body mass index (BMI), biopsy grade, and prostate-specific antigen, D'amico risk groups, and operative features including operative time, estimated blood loss, days of hospitalization, and the incidence of complications were recorded.

All specimens including those from the prostate, pelvic LNs, and PAFP were routinely examined in our pathology department after surgery. The number of LNs and the number of metastatic LNs were identified. Pathological features including pathological T stage, Gleason grade, extracapsular extension, margin status, and prostate size were also recorded.

A two-sided Student's t-test was used to test for differences in continuous data, and the Chi-square test for equality was used to compare categorical data. All statistical analyses were performed using Statistical Package for the Social Science software version 18.0 (IBM Corp., Armonk, NY, USA).

Results

Of the 194 patients who underwent RARP with pelvic LN dissection, 146 also underwent PAFP excision. After pathological analysis, 14 (9.6%) of 146 patients were found to have LNs in the PAFP (median number of LNs: 1; range: 1–4). Metastatic LNs were found in 2 (1.3%) of 146 patients, in whom positive pelvic LNs were not detected. There were another two patients who had obturator LN metastasis. The preoperative data of the patients with and without LNs in the PAFP were compared. There were no significant differences in age, BMI, prostate-specific antigen, or biopsy Gleason grade between these two groups. There were also no significant differences in pathological features including pathologic T stage, Gleason grade, extracapsular extension, margin status, or prostate size between the two groups. These patients were divided by D'amico risk stratification of prostate cancer. The probability of LN appearance is no difference between three risk groups [Table 1]. Average LN harvested in these patients (n = 194) from the right obturator LN was 3.13. LN from the left obturator LN was 2.86. The average number of LN harvested in PAFP removal group and without removal group is recorded in [Table 2].

Table 1: Features of the patients with and without lymph nodes in prostatic anterior fat pad

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Table 2: Average lymph node harvested in each group

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Furthermore, there were no significant differences in operative features and adverse effects between the patients who did and did not undergo PAFP excision [Table 3]. The two patients with positive nodes in the PAFP were classified as being at high-to-very high risk. No LNs were detected by preoperative magnetic resonance imaging in these two patients. Upstaging was noted according to the results of the pathological analysis. Both patients received adjuvant treatment [Table 4] after the surgery.

Table 3: Operative features between the patients with and without excision of prostatic anterior fat pad

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Table 4: Characteristics of the patients with metastatic lymph nodes in prostatic anterior fat pad

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Discussion

PLND is the standard practice during a radical prostatectomy for precise prostate cancer staging.^[1] In this study, we found that removal and analysis of PAFP increased the accuracy of staging without increasing the surgical risk. The rate of LNs found in the PAFP was 9.6%, with a metastatic LN rate of 1.3%.

Kim et al. reported a LN dissection rate in PAFP of 11.9%, with a metastatic LN rate of 0.94%. They also reported that metastatic LNs were only found in intermediate and high-risk groups.^[5] In addition, Hansen et al. reported LN dissection rate of 5.5%, with a metastatic LN rate of 1.2%.^[6] Another study by Aning et al. reported an LN rate of 17%, with a metastatic LN rate of 1.4%.^[8] Similar detected rate of LNs and metastatic LN rate in the PAFP was found between these studies and our report.

In our study, the patients with positive LNs in PAFP were all upstaged. Kwon et al. reported that 71.6% of patients with positive nodes in PAFP were upstaged based on their pathological analysis.^[9] We next investigated whether there were any preoperative parameters that could predict the presence of LNs in the PAFP; however, no such a parameter could be identified. Kwon et al. reported that patients with biopsy Gleason grade 8–10, N1 disease pathologically, and positive surgical margins are more frequently to have LNs in the PAFP, and a worse pathologic features may be expected.^[9] In our two patients showing positive node in the PAFP, both were with high-risk group with Gleason grade 4 + 5, stage above T3, and advanced PSA levels [Table 4].

There are several limitations in this study: first, the number of patients with positive LNs is small; second, all patients were operated in only one referral center in Taiwan; and third, the follow-up period is limited and therefore the long-term prognosis for PAFP node-positive patients is unknown in this study. Further long-term studies on the outcomes of patients with metastatic LNs in PAFP are warranted.

Conclusion

Our findings suggest that routine PAFP removal during RARP and pathological examination can identify upstaging and increase the accuracy of pathological staging. There was no increase in the surgical risk when removing PAFP, and therefore, we suggest that PAFP be routinely removed during an RARP and then analyzed pathologically to allow precise LN staging.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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