1) Lateral lymph nodes are an important consideration in rectal cancer as they can indicate regional or metastatic disease. 2) Preoperative identification of lateral lymph node involvement varies widely between studies but incidence of post-operative involvement is 17-40%. 3) While MRI is the primary staging tool, identification of lateral lymph node metastases remains challenging. Size criteria for involvement varies. 4) Management approaches differ between Western and Japanese guidelines but generally involve neoadjuvant chemoradiation followed by total mesorectal excision with or without lateral lymph node dissection depending on response.

1. Lateral lymph nodes in
rectal cancer
Pushpa Lal Bhadel
Department of Surgical oncology
BCH

2. Surgical anatomy
 Lymph nodes draining the rectum below
the peritoneal reflection:
o Along superior rectal artery & inferior
mesenteric artery into para-aortic nodes
o Along middle and inferior rectal artery into
obturator, internal iliac and external iliac
nodes
 TNM:
o Involvement of internal iliac LN: regional
disease
o External iliac nodes : metastatic disease
 Japanese classification: all lateral LN as
regional nodes Figure 1. Lymphatic drainage of the rectum highlighting the lateral LN

3. Fig. Lymphatic drainage system and LLNs in low rectal cancer

4. Incidence
 Pre-operative LLN involvement (Based on MRI)
Dharmarajan S et al 57 %
Ishibe et al 19.9%
MERCURY study group 11.7%
Ishihara et al 8.1%
 Incidence based on post-operative histopathology
Akiyoshi et al 40.3%
Moriya Y 23%
Ueno et at 17.3%
Quadros et al 17%
Significance of LLN metastasis
 Synchronous LLN disease in locally advanced tumors: 10-25% 1
 According to Japanese society- incidence of LLN in tumors below peritoneal
reflection: 27% 2
1 Wei M, Wu Q, Fan C, Li Y, Chen X, et al. (2016) Lateral pelvic lymph node dissection after neoadjuvant chemo-radiation for preoperative enlarged lateral nodes in advanced low rectal cancer: study
protocol for a randomized controlled trial. Trials17: 561
2 Watanabe T, Muro K, Ajioka Y, Hashiguchi Y, Ito Y, et al. (2018) Japanese Society for Cancer of the Colon and Rectum (JSCCR) guidelines 2016 for the treatment of colorectal cancer. Int J Clin Oncol 23: 1-34

5. Diagnosis of LN mets in rectal cancer
 MRI as primary staging tool:1
o Sensitivity: 55% and specificity: 78%
 Morphologic criteria: irregular border, heterogeneous signal intensity and round
shape in combination with size: 2
o Sensitivity (36%-85%) and specificity (95%-100%)
 Cutoff for LPLN size varies from 4 mm to 12 mm 3
 Diffusion weighted MR-imaging (DWI-MRI) for LLNs: LLN have high DWI signal 4
1 Lahaye MJ, Engelen SME, Nelemans PJ, et al. Imaging for predicting the risk factors—the circumferential resection margin and nodal disease—of local recurrence in rectal cancer: a meta-analysis. Seminars in
Ultrasound, CT and MRI. 2005;26(4):259-268
2 Kim JH, Beets GL, Kim MJ, Kessels AGH, Beets-Tan RGH. High-resolution MR imaging for nodal staging in rectal cancer: are there any criteria in addition to the size? European Journal of Radiology.
2004;52(1):78-83
4 Ogawa S, Itabashi M, Hirosawa T, Hashimoto T, Bamba Y, Okamoto T. Diagnosis of lateral pelvic lymph node metastasis of T1 lower rectal cancer using diffusion-weighted magnetic resonance imaging: A case
report with lateral pelvic lymph node dissection of lower rectal cancer. Molecular and Clinical Oncology. 2016;4(5):817-820
3 Kawai K, Shiratori H, Hata K, Nozawa H, Tanaka T, Nishikawa T, Murono K, Ishihara S. Optimal Size Criteria for Lateral Lymph Node Dissection After Neoadjuvant Chemoradiotherapy for Rectal Cancer. Dis
Colon Rectum. 2021;64:274–283

6. Managing the LLNs
Advantage of LLND: 1
 Decrease the intra-pelvic recurrence by 50%
 Improve the 5-year survival by 8%-9%
Western concept Japanese concept
Regional nodes Internal iliac nodes Internal, external and
common iliac and obturator
nodes
Metastatic nodes Common iliac, external iliac and
obturator nodes
Not applicable
Management nCRT with RT boost to involved nodes LLN dissection
1 Watanabe T, Muro K, Ajioka Y, Hashiguchi Y, Ito Y, et al. (2018) Japanese Society for Cancer of the Colon and Rectum (JSCCR) guidelines 2016 for the treatment of colorectal cancer. Int J Clin Oncol 23: 1-34

7. AJCC: combination of TME with radiation therapy (RT) and
Chemoradiation therapy (CRT) – standard treatment for advanced
lower rectal cancer
 Preoperative RT and CRT: partial local control effect
 Reduce local recurrence to ≤10%
NCCN: recommends TME after CRT with concomitant fluorouracil
for cStage II-III rectal cancer
 No specific description for LPLD
 Extended dissection of LNs located outside resection region to which LPLNs
correspond is indicated for resectable LNs with suspected mets
ESMO: preoperative RT and CRT recommended depending on the
risk
 LPLN mets is classified as advanced: preoperative CRT f/b surgery (TME +
extensive surgery) OR preoperative short-course RT + Folinic acid _
Fluorouracil + oxaliplatin (FOLFOX) regimen

8. Reassessment and preoperative treatment
 Restaging to be performed after neoadjuvant treatment
 Discussed during MDT meeting
 Surgical decisions based on response of LLNs
oCurrent evidence infers: Internal iliac LLNs >4mm (SA) and obturator LLNs >6
mm (SA) after CRT benefit from LLND
 Pt. with LLNs with complete clinical remission of both primary tumor
and LLNs after chemoradiation: careful assessment with MRI and
frequent f/u

9. Fig. Modified lithotomy (Lloyd-Davies) position

11. Complications
Intraoperative complications:
oLong operative time
oLarge volume blood loss
oInjury to ureter, gonadal vessels
Post-operative complications:
oUrinary and sexual dysfunction

12. LPLD and CRT for cLPLN(-) cases
 JCOG0212 randomized controlled trial :
o Outcomes of prophylactic LPLD in cLPLN(-) cases without suspected metastasis
o Examined TME alone compared to TME + LPLD
o 5-year relapse-free survival (RFS) was 73.4% in the LPLD group and 73.3% in the ME
group
o 5-year OS was 92.6% in the LPLD group and 90.2% in the ME group
o 5-year local recurrence-free rates were 87.7% in the LPLD group and 82.4% in the
ME group
o Local recurrence rate 26 cases (7.4%) vs 44 cases (12.6%) was significantly lower in
the LPLD group
o LPLD is effective for reduction of recurrence in this lateral pelvis region

13. LPLD and CRT for cLPLN(+) cases
 Kim et al:
o Local recurrence in 29 (7.9%) of 366 cases treated with TME alone without LPLD
after preoperative CRT.
o Recurrence in the lateral pelvis was found in 24 (82.7%) of these cases
o Local recurrence rates according to pretreatment LPLN size were 2.3%, 12.5% and
68.8% in cases with sizes < 5 mm, 5-10 mm and > 10 mm, showing that this rate was
high in cases with LPLN enlargement
 Akiyoshi et al: 127 CRT treated cases
o Performed TME alone in 89 cases without suspected LPLN metastasis before
treatment (the TME group) and TME + LPLD in 38 suspected cases (LPLD group)
o LPLN metastasis: 25 (65.8%) cases in the LPLD group, but local recurrence: 7 (7.9%)
cases in the TME group and 1 (2.6%) case in the LPLD group.
o Lateral pelvic recurrence was found in only 3 cases (3.4%) in the TME group and
none in the LPLD group

14. Yang et al:
oFound no difference in overall local recurrence in cases
with suspected LPLN metastasis
oIncidence of local recurrence in the lateral pelvic region
was significantly lower in the TME + CRT + LPLD group
than in the TME + CRT group

15. Conclusion
 Although the role of prophylactic LLND is unclear, it may have a role in
clinically positive lateral nodes and those that are resistant to CRT
 The major question that remains still unanswered is whether routine
TME + LLND post CRT in stage II and stage III rectal cancer needs to be
advocated globally based on the oriental experience
 The results from ongoing RCTs might provide an answer

16. Reference
 Bailey short practice of surgery, 27th edition
 Sabiston textbook of surgery, 20th edition
 Internet sources

17. Thank You