Pelvic Lymph Node Dissection

Introduction

Pelvic lymph node dissection (PLND) has a role in the treatment of several genitourinary cancers but is most commonly used in bladder cancer and prostate cancer. Others include urethral cancer and penile cancer. PLND has an additional role in the management of gynecologic cancers and other pelvic malignancies. While the anatomic approach is similar, the focus of this article is urologic indications.

History of the procedure

After it had been demonstrated that patients with breast and colon cancer with lymph node metastases could be cured surgically, attempts were made to apply lymphadenectomy to cancers of the pelvic organs. In 1932, Godard and Kaliopoulos reported pelvic lymphadenectomy with total cystectomy for bladder cancer. In 1950, Leadbetter and Cooper also were proponents of pelvic lymphadenectomy with cystectomy for bladder cancer.

Indications

The principal urologic indications for PLND occur in bladder cancer and in prostate cancer. Other urologic scenarios in which PLND is performed include selected cases of urethral and penile cancer.

Bladder cancer

In bladder cancer, pelvic lymph node dissection (PLND) is performed at the time of a radical cystectomy or a partial cystectomy. For these patients, PLND provides staging information and can be therapeutic. Several studies, including by Skinner ^[1] and Vieweg et al, ^[2] have confirmed that patients with pelvic lymph node metastases can be cured with PLND during radical cystectomy. However, the curability seemed to hold for organ-confined cancer (pathologic T stage 2) but not for non–organ-confined cancer (pathologic T stage 3). ^[3]

For more information go to Bladder Cancer.

Prostate cancer

The decision to perform PLND for prostate cancer prior to performing radical retropubic prostatectomy is based on the probability of pelvic lymph node metastases. This can be determined using the Partin nomograms. ^[4] The Partin nomograms are included in the tables below (these and other nomograms are available at the Prediction Tools Page of MSKCC.org).

For more information, go to Prostate Cancer.

Table 1. Multivariate Logistic Regression Analysis for Prediction of Pathologic Stage Using Prostate-Specific Antigen, Gleason Score, and Clinical Stage (TNM): Prediction of Organ-Confined Disease (Percent) (Open Table in a new window)

Table 2. Multivariate Logistic Regression Analysis for Prediction of Pathologic Stage Using Prostate-Specific Antigen, Gleason Score, and Clinical Stage (TNM): Prediction of Lymph Node Status (Percent) (Open Table in a new window)

The following is an example of a clinical scenario in which the Partin nomograms are used to determine the percent probability of lymph node involvement: With a stage of T2a, a prostate-specific antigen level of 14 ng/mL, and Gleason sum of 6, the nomogram calculates a 38% probability of organ-confined disease, a 52% probability of capsular penetration, a 5% probability of seminal vesicle involvement, and a 4% probability of lymph node involvement.

The threshold for performing PLND for prostate cancer is determined by the Partin nomograms, but it varies with the treatment modality used. For an open retropubic prostatectomy, PLND adds minimal morbidity. Therefore, a 3% probability of lymph node involvement is used as a threshold above which one would perform a PLND.

For a perineal prostatectomy, PLND requires an extra operation, and a 10% cutoff is used. In patients who undergo external beam radiation therapy and who may benefit from radiation as treatment for microscopic pelvic lymph node–positive disease, a 35% cutoff is used.

A study by Moschini et al reported that in pT3-T4 prostate cancer patients, removal of a higher number of lymph nodes during radical prostatectomy was associated with higher cancer-specific survival rates. The authors added that this study supported the role of more extensive PLND in this patient group, however, further studies are needed to validate these findings. ^{[5, 6]}

A systematic review by Fossati et al that included 66 studies and 275,269 patients suggested that although the quality of data was poor, pelvic lymph node dissection in patients undergoing radical prostatectomy for prostate cancer may not have any direct benefit on cancer outcomes and may result in greater adverse outcomes. However, PLND remains acceptable because of its accurate assessment of cancer metastasis. Further studies are needed. ^[7]

Penile cancer

Pelvic lymphadenectomy in the setting of penile cancer is controversial. However, an argument can be made that PLND is a reasonable therapy for a young patient, given that some evidence shows that pelvic lymphadenectomy may lengthen survival. Adjuvant chemotherapy should also be considered if pelvic lymph nodes are positive.

Urethral cancer

Primary cancers of the entire urethra or posterior urethra in females and in the bulbomembranous urethra in males are usually associated with invasion and a high incidence of pelvic nodal metastases. Pelvic lymphadenectomy is performed along with exenterative surgery because, occasionally, patients with nodal metastases can be cured.

Urethral carcinoma in male patients is classified into 3 groups based on the location of the lesion: (1) penile, (2) bulbomembranous, or (3) prostatic. Most cases (59%) occur posteriorly and involve the bulbomembranous urethra. Less frequent sites include the penile (33%) and the prostatic (7%) portions. In women, approximately 50% of carcinomas occur in the distal urethra.

Lymphatic metastases in the inguinal lymph nodes typically result from tumor in the anterior urethra, while pelvic lymphatic metastases are associated with posterior urethral tumors. Like its male counterpart, the female urethra has an anterior portion that comprises the distal one third of the urethra and a posterior portion that comprises the remaining proximal two thirds. The distal third drains into the inguinal nodes, and the proximal two thirds empty into the pelvic lymph nodes.

Contraindications

Metastatic prostate cancer that involves the pelvic lymph nodes is generally considered to be incurable with surgery. In such cases, PLND cannot be undertaken as a therapeutic procedure; instead, its purpose is to accurately determine whether the patient would benefit from more aggressive, definitive therapy. Essentially, the PLND is a staging procedure that can prevent the morbidity of a radical prostatectomy in patients unlikely to benefit from the procedure.

Pelvic lymphadenectomy in the setting of penile cancer is controversial. General agreement indicates that the probability of finding positive pelvic lymph nodes is increased in the presence of positive inguinal lymph nodes. Also known is the fact that survival of patients with positive iliac nodes is limited. Therefore, some would argue against PLND for penile cancer.

Relevant Anatomy

There are 8-10 external iliac lymph nodes. These receive efferent lymphatics from the inguinal nodes, the lymphatics of the iliac fossa, and the lower anterior abdominal wall and afferent lymphatics from the pelvic viscera

The internal iliac lymph nodes receive afferents from the pelvic viscera. Their efferents pass to the common iliac nodes.

There are 4-6 common iliac nodes whose efferent lymphatics pass to the lumbar nodes.

The lymphatics of the pelvis follow the arteries, and the group of nodes accompanying each is named accordingly: internal iliac, external iliac, and common iliac. See the image below.

The details of lymphatic drainage from each organ of the pelvis are outlined in the table below.

Table 3. Pelvic Lymph Node Drainage (Open Table in a new window)

See Lymphatic System Anatomy for more information.

Imaging Studies

Prediction of lymph node status can help in preoperative staging for pelvic lymph node dissection (PLND). CT scanning is used most commonly for this purpose. This imaging modality has been evaluated in numerous studies of pelvic lymph node metastases in bladder cancer. ^[8]

Studies by several groups have found sensitivities of detecting pelvic lymph node metastases ranging from 10-94%, for a cumulative sensitivity of only 48%. However, when detected, nodal enlargement is specific, with a range of 83-100%, for a cumulative specificity of 94%. Approximately 40% of cases are under staged, and approximately 5% are overstaged.

In bladder cancer, staging with pelvic CT scanning can provide information about the bladder tumor and the presence of pelvic or para-aortic lymphadenopathy. However, the presence of lymphadenopathy does not necessarily indicate metastatic disease. Moreover, CT scanning can fail to reveal nodal metastases in up to 40% of cases.

Another study concluded that PET/CT was significantly successful in detecting lymph node metastases in patients with high-risk prostate cancer with high specificity but low sensitivity. ^[9]

In prostate cancer, the staging information that is useful for PLND includes T stage, prostate-specific antigen level, and Gleason score. Currently, imaging studies have no role in the evaluation of the pelvic lymph nodes.

Overview

Intraoperative details of pelvic lymph node dissection (PLND) are different when the procedure is performed for patients with bladder cancer than when it is performed for those with prostate cancer.

PLND for Bladder Cancer

The operative limits of PLND in bladder cancer are as follows:

• Cephalad - 2 cm above the bifurcation of the common iliac artery

• Caudad - the endopelvic fascia

• Medial - the bladder

• Lateral - the genitofemoral nerve

A PLND for bladder cancer is usually performed in conjunction with a radical cystectomy. A modified dissection, leaving the nodes along the external iliac artery intact, may be appropriate in low-risk patients because skeletonization of the external iliac artery is associated with an increased risk of lymphedema.

For the procedure, position the patient supine in the dorsal lithotomy position. Make a midline lower-abdominal incision. For a PLND in conjunction with a radical cystectomy, the incision should extend from the pubic symphysis to above the umbilicus. Incise the fascia and peritoneum at the level of the umbilicus.

Explore the abdominal and pelvic viscera and para-aortic nodes for evidence of metastatic spread. Then dissect the peritoneum off the posterior rectus sheath.

Develop a flap of peritoneum in the shape of a V, with its apex at the umbilicus and its ends directed toward the internal inguinal rings. Grasp the apex and pull it caudad.

Incise the peritoneum and investing tissue covering the external iliac vessels to the bifurcation of the common iliac artery. Isolate the ureters as they pass in front of the common iliac arteries.

Dissect free the psoas and iliopsoas muscles.

Skeletonize the external iliac artery from the inguinal ligament to 2 cm above the bifurcation of the common iliac artery. Identify and preserve the circumflex iliac, inferior epigastric vessels, and the genitofemoral nerve.

Divide the nodal package anteromedially over the external iliac artery. Roll the tissue posteriorly off the artery, and then dissect it off the external iliac vein.

Dissect the fat overlying the fascia of the psoas and iliopsoas muscles. Identify the obturator fossa by retracting the bladder medially, and ligate and divide the obturator vessels. Carry the dissection of fat and nodes medially and superiorly along the obturator vessels. At the junction of the obturator vessels with the internal iliac vessels, ligate and divide the obturator vessels, if necessary.

Remove the pelvic lymph node packet, and send it for histologic evaluation.

Repeat the procedure on the opposite side.

Robot-assisted technique

Extended PLND can be performed using a robot-assisted device. While some authorities remain skeptical that adequate nodal yields can be achieved with minimally invasive modalities, Lavery et al suggest that comparable nodal dissection can be achieved using a robotic technique, and that the yield is more a function of surgeon effort and expertise than modality used. ^[10]

PLND for Prostate Cancer

PLND in prostate cancer can be performed as either an open or a laparoscopic procedure. In addition, the open procedure can be performed as part of a radical prostatectomy or as a minilaparotomy. The minilaparotomy and laparoscopic approaches can be used when a perineal approach is being considered.

Laparoscopic lymph node dissections and nodal sampling through minilaparotomy are options for patients who are receiving ablative therapies for prostate cancer (eg, cryotherapy) or investigative treatments (eg, high-intensity focused ultrasound [HIFU]) in which lymph node dissection for staging is often not used. This is especially true for patients at high risk of node-positive disease, such as those with a prostate-specific antigen level of more than 20 ng/mL, a Gleason grade of 8-10, or high-risk biopsy data.

The discussion that follows applies to both the open and laparoscopic approach, with procedural information specific to each and then information common to both. However, the technical aspects of laparoscopy are not addressed in this article.

The limits of node dissection for PLND in prostate cancer are as follows:

• Cephalad - the bifurcation of the common iliac artery

• Caudad - the node of Cloquet

• Medial - the obturator vessels

• Lateral - the pelvic sidewall

For open PLND in a patient with prostate cancer, make a midline lower-abdominal incision that extends from the pubic symphysis to just below the umbilicus. Incise the anterior rectus fascia at the decussation of the fibers along the length of the skin incision.

Incise the transversalis fascia beneath the rectus muscle. This allows mobilization of the peritoneum medially and cephalad.

Isolate, divide, and ligate the vas deferens.

Gain exposure with a Bookwalter retractor. To retract the bladder, place a malleable retractor blade on one side of the nodes and a straight blade on the opposite side. Place a Jackson retractor on top of the external iliac vein.

The procedure specifically for laparoscopic PLND is to create a pneumoperitoneum and obtain laparoscopic access using 3 operating ports. Incise the peritoneum midway between the internal ring and the obliterated umbilical artery to expose the external iliac vein.

The procedure common to both the open and the laparoscopic techniques is as follows: Skeletonize the external iliac vein. Clean down to the pelvic sidewall alongside the external iliac vein, and insert a vein retractor.

Push the fatty tissue along the Cooper ligament, laterally toward the distal margin of the nodal packet. Tease the node of Cloquet from the femoral canal. Clip and divide.

Identify and preserve the obturator nerve and vessels.

Remove the pelvic lymph node packet, and send it for histologic evaluation.

Repeat the procedure on the opposite side.

The video below shows a pelvice lymph node dissection as part of a radical retropubic prostatectomy.

Patients with bladder cancer only occasionally benefit from pelvic lymph node dissection (PLND). Approximately 20% of patients present with lymph node metastases. This percentage is higher in selected populations considered to have high grade and stage disease. Approximately 50% of these patients have limited regional metastases (1 or 2 nodes below the iliac bifurcations) and are theoretically amenable to cure. Of these patients, 10-35% are cured with cystectomy and PLND alone.

The management of prostate cancer accompanied by lymph node metastases after permanent histologic evaluation is controversial. The debate centers on whether to institute hormonal therapy immediately or upon prostate-specific antigen progression. ^[11] Given that the prostate-specific antigen (PSA) level is a good index of disease progression, an argument can be made to delay treatment until the PSA level rises.

On the other hand, 4 prospective randomized trials have supported a survival benefit of early androgen ablation in locally advanced disease. ^[12] Messing et al demonstrated a 25% overall survival benefit at 8 years in men with node-positive prostate cancer treated with radical prostatectomy and orchidectomy/goserelin compared with radical prostatectomy alone. ^[11]

Complications

Several complications of pelvic lymph node dissection (PLND) are common to both bladder and prostate cancer. During dissection of the lymph nodes, acute bleeding may result from injury to the iliac vessels. Treatment entails repair of the vascular injury using an open surgical technique.

Postoperative development of a deep vein thrombosis, with the possibility of a resultant pulmonary embolism, remains a significant problem with PLND. Postoperative prophylaxis with subcutaneous heparin can decrease this risk.

Obturator nerve injury with resultant loss of adduction of the thigh is rare.

Development of a symptomatic lymphocele is also rare. Treatment includes conservative management, percutaneous drainage, or marsupialization.

Lymphedema of the extremities can result in significant morbidity. Sparing of the lymphatics lateral to the iliac vessels can decrease the rate of this complication.

Patient Education

For patient education information, see the Cancer and Tumors Center, as well as Bladder Cancer.