Lymph Nodes Taken for Staging in Radical Prostatectomy
For appropriately risk-selected patients undergoing pelvic lymph node dissection (PLND) at radical prostatectomy, an extended template should be performed, which includes the obturator fossa, external iliac, and internal iliac lymph nodes bilaterally. 1
Anatomic Templates for PLND
The 2022 AUA/ASTRO guidelines define PLND templates using anatomic landmarks as follows: 1
- Limited: Obturator fossa only
- Standard: Limited plus external iliac lymph nodes
- Extended: Standard plus internal iliac lymph nodes
- Super-extended: Extended plus common iliac, presacral and/or other nodes
Why Extended PLND is Recommended
Extended PLND provides superior staging accuracy compared to limited dissection. The evidence demonstrates that extended dissection results in higher lymph node counts and greater positive lymph node yield, which is critical for accurate staging and informing subsequent treatment decisions. 1
Critical Staging Evidence
Research shows that 19-58% of lymph node metastases occur in the internal iliac region, and in approximately 19% of node-positive cases, the internal iliac nodes are the only site of metastasis. 2, 3 This means that limiting dissection to the obturator fossa alone would miss nearly one-fifth of patients with lymph node involvement. 2
Studies comparing templates found:
- Extended PLND retrieves a median of 21-28 lymph nodes versus 12 nodes with limited dissection 2, 3, 4
- In high-risk patients, extended PLND detected positive nodes in 20% of cases versus only 7% with standard dissection (p<0.01) 5
- In 69% of node-positive cases, metastases were found in internal/external iliac regions despite negative obturator nodes 5
Risk-Stratified Approach to Performing PLND
PLND should be performed using a risk-stratified approach based on nomogram-predicted probability of lymph node involvement. 1 The decision to perform PLND should involve shared decision-making, discussing the patient's calculated risk of positive nodes, the staging benefit, and the risks of lymphocele formation. 1
When to Perform PLND
While specific thresholds vary, the evidence supports PLND for patients with: 3
- PSA >10.5 ng/mL AND biopsy Gleason score ≥7 (risk of lymph node metastasis ~26%)
- Patients with PSA <10.5 ng/mL and Gleason <7 have only 2% risk and PLND may be omitted 3
Common pitfall: The 2011 NCCN nomogram recommending PLND at 2% risk threshold was derived from limited PLND cohorts and significantly underestimates actual lymph node invasion rates (by up to 41%) when extended PLND is performed. 1 Using the 2% cutoff would miss 20% of patients with lymph node involvement. 1
Operative Considerations
Extended PLND increases operative time and carries a slightly higher risk of lymphocele formation (approximately 8.6% vs 3.4% for grade ≥3 complications), but does not significantly increase other complications or blood loss. 1, 5, 3, 4
Intraoperative Management
If suspicious regional nodes are encountered intraoperatively, clinicians should complete the radical prostatectomy rather than abort the procedure. 1 Retrospective data demonstrate benefit to completion of surgery versus aborting and treating with androgen deprivation therapy alone. 1
Post-PLND Management
Patients with positive lymph nodes should be risk-stratified based on pathologic variables (particularly number of positive nodes) and postoperative PSA. 1 For patients with undetectable postoperative PSA, either adjuvant therapy or observation may be offered, as up to 30% remain disease-free long-term without further treatment. 1