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SUO 2023

SUO 2023: Robotic Inguinal Lymph Node Dissection

(UroToday.com) The 2023 SUO annual meeting included a session on penile cancer, featuring a presentation by Drs. Reza Mehrazin and Alice Yu discussing robotic inguinal lymph node dissection. Dr. Mehrazin took the pro stance for a robotic approach, discussing robotic-assisted video-endoscopic inguinal lymphadenectomy (RAVEIL) in penile cancer.


From an epidemiology standpoint, penile cancer is a rare malignancy, accounting for 0.4-0.6% of all cancers in men in the United States and Europe, but with up to 25% of patients presenting with advanced disease. Inguinal lymph node status has been found to be the most important prognostic predictor of cancer specific survival: patients with negative lymph nodes have a 5-year cancer specific survival of ~95%, where as those with N1 have 80% 5-year cancer specific survival, N2 has 65% and N3 has 35%. Patients that are low risk (Tis, Ta, T1a) should have local therapy followed by surveillance of the inguinal lymph nodes, whereas intermediate risk (T1b) or high risk (>= T2) patients should have prophylactic bilateral inguinal lymph node dissection or sentinel lymph node biopsy.

Although inguinal lymph node dissection is diagnostic and has a survival benefit, open dissection has complication rates of 50-100%, including flap necrosis, leg edema, lymphocele/seroma, wound infection, and deep vein thrombosis. Factors associated with lower complication rate include:

  • Dynamic sentinel lymph node biopsy
  • Prevention of surgical site infection
  • Modified inguinal lymph node dissection template (ie. saphenous vein sparing, drainage, fascial sparing)
  • Post-surgical lymphedema prevention and care
  • DVT prophylaxis
  • A minimally invasive surgical approach

A minimally invasive approach to inguinal lymph node dissection was initially described in 2006, with Dr. Master and colleagues providing long-term follow-up of their series in 2012.1 Among 29 patients undergoing 41 minimally invasive lymphadenectomies (with different malignancies), there were no Clavien IIIb-V complications, with a reasonable Clavien I-IIIa complication rate:
In 2018, Singh and colleagues reported a comparison of outcomes between robotic (n = 51) and open (n = 100) inguinal lymph node dissection in patients with penile cancer.2 They found that RAVEIL and open inguinal lymph node dissection had comparable median lymph node yields (13 vs 12.5), and no patient experienced recurrence during a median 40 month follow-up. RAVEIL was associated with significantly lower:

  • Hospital stay
  • Days needing a drain in situ
  • Incidence of major complications
  • Edge necrosis
  • Flap necrosis
  • Severe limb edema

Of note, operative time for RAVEIL was longer (median 75 min vs 60 min, p < 0.0001). On multivariable analysis, pathological nodal stage (OR 2.8, 95% CI 1.1-6.8, p = 0.027) and open inguinal lymph node dissection (OR 7.5, 95% CI 1.3-43, p = 0.024) were risk factors associated with an increased risk of major complications.

A systematic review and meta-analysis comparing RAVEIL and video-endoscopic inguinal lymphadenectomy (VEIL) versus open inguinal lymph node dissection (OILND) assessed 8 studies (including two randomized clinical trials) of 213 minimally invasive surgery patients versus 283 open surgery patients.3 In this study, the RAVEIL/VEIL group was superior to OILND in:

  • Shorter hospital stay: MD = -1.06 (-1.14; -0.98), p < 0.001
  • Decreased duration of drainage: MD = -2.82 (-3.21; -2.43), p < 0.001
  • Wound infection rate: OR = 0.15 (0.08; 0.27), p < 0.001
  • Skin necrosis rate: OR = 0.12 (0.05; 0.28), p < 0.001
  • Lymphedema rate: OR = 0.41 (0.24; 0.72), p = 0.002
  • Major complication rate: OR = 0.11 (0.05; 0.24), p < 0.001
  • Slightly larger lymph node yield: MD = 0.44 (0.18; 0.70), p < 0.001

Recurrence rate and number of deaths were comparable in both groups. Of note, RAVEIL/VEIL was inferior to open lymph node dissection with longer operative time (MD = 15.28 [14.19; 16.38], p < 0.001).

With regards to single port RAVEIL, Dr. Mehrazin notes that there have been two prior case reports, as well as his current case series that is In Press in Endourology. For this procedure, Dr. Mehrazin notes that the patient is positioned supine on a split table, with the legs abducted and externally rotated with the knees slightly flexed. The lateral border (the sartorius muscle) is marked 20 cm down from the ASIS, the medial border (adductor longus) is marked 15 cm down from the pubic tubercle, and the cephalad margin is the inguinal ligament. The incision is carried down to the subcutaneous layer to the level of fascia lata, and the space is developed with an index finger. With multiport inguinal lymph node dissection, Dr. Mehrazin notes that he used to use the balloon spacer, but with the SP robot this is unnecessary for making space for trocars:
Dr. Mehrazin concluded his presentation discussing the pro aspect of robotic inguinal lymph node dissection with the following take-home points:

  • Overall, a robotic approach seems to be non-inferior to open inguinal lymph node dissection from an oncological standpoint, with the added benefit of lower high grade complication rate
  • A single port RAVEIL approach can also be a feasible option for patients undergoing inguinal lymph node dissection
  • However, prospective studies with larger case-series with longer follow-up

Dr. Alice Yu then discussed the con stance for robotic inguinal lymph node dissection. She started by emphasizing that in high risk patients with non-palpable lymph nodes, early detection of lymphatic spread is crucial. We know that in contemporary series of open inguinal lymph node dissection, more than 50% will have a post-operative complication and thus we must improve minimally invasive approaches, especially with cN0 cases. However, there are open techniques that decrease the risk of complications, including a modified template approach, saphenous vein preservation, fascia lata preservation, and dynamic sentinel lymph node dissection.

With regards to dynamic sentinel lymph node biopsy, traditionally this approach has had a false negative rate of 22%, with a steep learning curve. Moreover, there are lower false-negative rates in high volume centers, but this requires multidisciplinary expertise in nuclear medicine, urology, and pathology. Innovations for dynamic sentinel lymph node biopsy include dual labeled/hybrid tracers, which combines traditional radioactive 99mTc-nanocolloid and fluorescent indocyanine green, allowing radio- and fluorescent guidance with ICG-99mTc-nanocolloid – the best of both worlds. In a 2020 published study in European Urology, the aim was to confirm the reliability of ICG-99mTc-nanocolloid and to assess whether blue dye is still of added value.4 This study included 400 men with ≥T1G2N0 penile cancer who were staged with sentinel biopsy; sentinel nodes were preoperatively identified with lymphoscintigraphy and SPECT-CT. Intraoperatively, sentinel nodes were detected via gamma tracing, blue staining, and fluorescence imaging. Among 740 groins assessed, all preoperatively defined sentinel lymph nodes (n=1,163) were localized intraoperatively. Among all excised sentinel lymph nodes, 98% were detectable with gamma probe and 96% were visible with fluorescence imaging. In patients who received ICG-99mTc-nanocolloid and blue dye, fluorescence imaging yielded a 39% higher sentinel node detection rate than blue dye (95% CI 36-43%, p<0.001). Furthermore, of the sentinel nodes that were tumor positive, 100% were intraoperatively visualized by fluorescence imaging, whereas only 84% of the positive nodes stained blue:
Although there is much excitement surrounding minimally invasive inguinal lymphadenectomy for penile cancer, Dr. Yu notes that currently we still lack data to solidify this approach as standard of care. As mentioned in Dr. Mehrazin’s portion of the discussion, Singh and colleagues reported a comparison of outcomes between robotic (n = 51) and open (n = 100) inguinal lymph node dissection in patients with penile cancer, with the following findings:2image-3.jpg
Regardless of how enticing a minimally invasive approach may be, there will always be patients who require an open approach based on disease characteristics, including those with bulky inguinal lymphadenopathy:bulky inguinal lymphadenopathy imageoperation photo
Management of locoregional recurrence is also important, with Dr. Yu highlighting a multicenter (international study across 4 centers) study (including patients from his group at Moffitt) of patients undergoing salvage inguinal resection for penile cancer recurrence following inguinal lymph node dissection.5 Among 20 patients meeting criteria, the mean time to recurrence was 7.7 months. At the time of salvage inguinal lymph node dissection, a median of 3 lymph nodes (range 1 to 17) were resected, with a median of 2 (range 1 to 7) nodes positive for malignancy. The median disease specific survival was 16.4 months, and median overall survival was 10.1 months. Of the initial cohort, nine patients were without evidence of disease and post-op complications occurred in 11 patients, including wound infections in six patients, postoperative severe (debilitating) lymphedema in four patients, and seroma in one patient.

Finally, Dr. Yu notes that the learning curve for a minimally invasive robotic approach is somewhat difficult to quantify. Generally, the mean lymph node yield is 5-6 per side with the videoscopic approach. 

Dr. Yu concluded her presentation discussing the con aspect of robotic inguinal lymph node dissection with the following take-home points:

  • There is a questionable learning curve associated with the robotic approach
  • No clear conclusions can be made about recurrence rates
  • The robotic approach is not ideal for bulky tumors, post-chemoradiation, or redo operations
  • Overall, patient selection is key

Presented by:

Reza Mehrazin, MD, FACS, Mount Sinai Hospital, New York, NY

Alice Yu, MD, Moffitt Cancer Center, Tampa, FL 

Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Associate Professor of Urology, Georgia Cancer Center, Wellstar MCG Health, @zklaassen_md on Twitter during the 2023 Society of Urologic Oncology (SUO) Annual Meeting, Washington, D.C., Tues, Nov 28 – Fri, Dec 1, 2023.

References:

  1. Master VA, Jafri SM, Moses KA, et al. Minimally invasive inguinal lymphadenectomy via endoscopic groin dissection: Comprehensive assessment of immediate and long-term complications. J Urol. 2012 Oct;188(4):1176-1180.
  2. Singh A, Jaipuria J, Goel A, et al. Comparing Outcomes of Robotic and Open Inguinal Lymph Node Dissection in Patients with Carcinoma of the Penis. J Urol. 2018 Jun;199(6):1518-1525.
  3. Patel KN, Salunke A, Bakshi G, et al. Robotic-Assisted Video-Endoscopic Inguinal Lymphadenectomy (RAVEIL) and Video-Endoscopic Inguinal Lymphadenectomy (VEIL) versus Open Inguinal Lymph-Node Dissection (OILND) in carcinoma of penis: Comparison of perioperative outcomes, complications, and oncological outcomes: A systematic review and meta-analysis. Urol Oncol. 2022;40:112.e11-112.e22.
  4. Dell’Oglio P, de Vries HM, Mazzone E, et al. Hybrid Indocyanine Green-99mTc-nanocolloid for single-photon emission computed tomography and combined radio- and fluorescence-guided sentinel node biopsy in penile cancer: Results of 740 inguinal basins assessed at a single institution. Eur Urol 2020 Dec;78(6)865-872.
  5. Baumgarten AS, Alhammali E, Hakky TS, et al. Salvage surgical resection for isolated locally recurrent inguinal lymph node metastasis of penile cancer: International study collaboration. J Urol. 2014 Sep;192(3):760-764.