Dear Editor
In a recent issue of BJS, Lokuhetty et al.1 highlighted the importance of appropriate patient selection for lateral pelvic lymph node dissection (LPLND) in rectal cancer. A consensus approach to the assessment and treatment of lateral pelvic lymph nodes (LPLNs) is still evolving. The additional value of therapeutic LPLND to reduce lateral local recurrence is also currently being discussed in the multidisciplinary community treating rectal cancer.
Although the role of therapeutic LPLND is becoming established, there remains a need to better select patients who should undergo this procedure based on clinical evaluation, and there is no clear consensus at present1. The previous equipoise between Eastern and Western strategies for the management of LPLN metastases demonstrated that not all patients required LPLND nor was neoadjuvant chemoradiation sufficient to prevent lateral local recurrence2. The current treatment guidelines advocate against LPLND unless there is a clinical suspicion of metastasis, and there are associated risks of LPLND. Therefore, it is imperative that decision-making treatment strategies are developed to accurately identify which patients are most likely to have LPLN metastases after neoadjuvant therapy. It is also unclear whether leaving treated nodes worsens the lateral local recurrence rate2.
Traditionally, size of the LPLN has been the main criterion for determining the need for therapeutic LPLND2. However, LPLN metastases can still be detected in patients with a short-axis LPLN diameter of 4 mm or less despite neoadjuvant chemoradiation, highlighting the limitations of size as the single criterion for therapeutic LPLND3. It is therefore essential to identify other features that might facilitate the identification of patients requiring therapeutic LPLND after neoadjuvant therapy.
A recent study by the authors’ group4 demonstrated that, in addition to size, pretreatment malignant features, such as internal heterogeneity and/or border irregularity, were also independent predictors of LPLND. Furthermore, enlarged LPLNs harbouring these malignant features may be associated with worse distant metastasis-free survival5. These malignant features in LPLNs appear to be an important independent predictor of LPLN metastases, and therefore should be considered in addition to size in treatment stratification2.
Moreover, it was demonstrated that an MRI-directed multidisciplinary decision-making strategy, combining morphological features and LPLN size, can facilitate the appropriate selection of patients for LPLND, without increasing the risk of lateral local recurrence4. Importantly, there was also no difference in perioperative or oncological outcomes between patients who or did not undergo LPLND4. This was the first study to assess the role of LPLND or observation in patients presenting with evidence of LPLN metastases before completing total neoadjuvant therapy (TNT), and then to evaluate a multidisciplinary decision-making algorithm to determine which patients will most likely benefit from LPLND4.
The authors have endeavoured to further this work in expanding the multidisciplinary decision-making algorithm to determine which patients will most likely benefit from therapeutic LPLND after TNT. The peritoneal reflection is a useful landmark in determining the location of the rectal tumour, and is now documented as part of the synoptic MRI reporting at this institution. Retrospective analysis of a cohort of 158 patients with rectal cancer and clinically evident LPLN metastases on pretreatment MRI demonstrated very few tumours above the peritoneal reflection and enlarged LPLNs (Table 1). The data also showed that patients whose tumours were above the peritoneal reflection were far less likely to undergo LPLND (OR 0.15, 95 per cent c.i. 0.04 to 0.64; P = 0.013).
Table 1.
Primary tumour location in relation to peritoneal reflection in patients with lateral pelvic lymph nodes dissected or not dissected
| LPLNs not dissected (n = 70) |
LPLNs dissected (n = 88) |
P* | |
|---|---|---|---|
| Tumour location | 0.013 | ||
| Below | 18 (26%) | 39 (44%) | |
| Straddles | 39 (56%) | 43 (49%) | |
| Above | 9 (13%) | 3 (3.%) |
Values are n (%). Tumour location was not available for seven patients. LPLN, lateral pelvic lymph node. *Chi-square test.
In summary, the authors advocate the use of MRI-directed multidisciplinary decision-making algorithms, utilizing LPLN size, presence of malignant features, and relationship of primary tumour to the peritoneal reflection, when determining which patients will benefit from therapeutic LPLND after neoadjuvant therapy.
Contributor Information
Oliver Peacock, Department of Colon and Rectal Surgery, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Naveen Manisundaram, Department of Colon and Rectal Surgery, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Youngwan Kim, Department of Colon and Rectal Surgery, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Tsuyoshi Konishi, Department of Colon and Rectal Surgery, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Nir Stanietzky, Department of Abdominal Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Raghunandan Vikram, Department of Abdominal Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Brian K Bednarski, Department of Colon and Rectal Surgery, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Y Nancy You, Department of Colon and Rectal Surgery, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
George J Chang, Department of Colon and Rectal Surgery, University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Funding
This study was supported by the Aman Trust (G.J.C.), the Andrews Family Fund (G.J.C.), and the National Institutes of Health/National Cancer Institute grants T32 CA009599 and CA016672 (University of Texas MD Anderson Cancer Center Support Grants).
Author contributions
Oliver Peacock (Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Supervision, Validation, Writing—original draft, Writing—review & editing), Naveen Manisundaram (Data curation, Formal analysis, Investigation, Methodology, Project administration, Software, Validation, Writing—review & editing), Youngwan Kim (Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Software, Validation, Writing—review & editing), Tsuyoshi Konishi (Conceptualization, Formal analysis, Investigation, Methodology, Project administration, Validation, Writing—review & editing), Nir Stanietzky (Conceptualization, Formal analysis, Investigation, Methodology, Project administration, Resources, Validation, Visualization, Writing—review & editing), Raghunandan Vikram (Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software, Validation, Writing—review & editing), Brian Bednarski (Conceptualization, Formal analysis, Investigation, Methodology, Project administration, Supervision, Validation, Writing—review & editing), Y. Nancy You (Conceptualization, Formal analysis, Investigation, Methodology, Project administration, Supervision, Validation, Writing—review & editing), and George Chang (Conceptualization, Formal analysis, Investigation, Methodology, Project administration, Supervision, Validation, Writing—review & editing).
Disclosure
G.J.C. is consultant for Medicaroid. The authors declare no other conflict of interest.
Data availability
Limited data may be available upon request.
References
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Associated Data
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Data Availability Statement
Limited data may be available upon request.