Lateral lymph node and its association with distant recurrence in rectal cancer: A clue of systemic disease

Interdisciplinary Spanish consensus on a watch-and-wait approach for rectal cancer

Watch-and-wait has emerged as a new strategy for the management of rectal cancer when a complete clinical response is achieved after neoadjuvant therapy. In an attempt to standardize this new clinical approach, initiated by the Spanish Cooperative Group for the Treatment of Digestive Tumors (TTD), and with the participation of the Spanish Association of Coloproctology (AECP), the Spanish Society of Pathology (SEAP), the Spanish Society of Gastrointestinal Endoscopy (SEED), the Spanish Society of Radiation Oncology (SEOR), and the Spanish Society of Medical Radiology (SERAM), we present herein a consensus on a watch-and-wait approach for the management of rectal cancer. We have focused on patient selection, the treatment schemes evaluated, the optimal timing for evaluating the clinical complete response, the oncologic outcomes after the implementation of this strategy, and a protocol for surveillance of these patients.

MRI-based Multiregional Radiomics for Pretreatment Prediction of Distant Metastasis After Neoadjuvant Chemoradiotherapy in Patients with Locally Advanced Rectal Cancer

RATIONALE AND OBJECTIVES

To develop and validate a nomogram based on intratumoral and peritumoral radiomics signatures for pretreatment prediction of distant metastasis-free survival (DMFS) in patients after neoadjuvant chemoradiotherapy (NCRT) with locally advanced rectal cancer (LARC).

MATERIALS AND METHODS

This retrospective study included 230 patients (161 training cohort; 69 validation cohort) with LARC who underwent NCRT and surgery. Radiomics features were extracted on T2-weighted images from gross tumor volume (GTV) and volumes of 4-mm, 6-mm, and 8-mm peritumoral regions (PTV4, PTV6, and PTV8). The least absolute shrinkage and selection operator (LASSO)-Cox analysis were used for features selection and models construction. The performance of each model in predicting DMFS was evaluated by the Concordance index (C-index) and time-independent receiver operating characteristic curve (ROC).

RESULTS

The PTV4 radiomics model demonstrated superior performance compared to the PTV6 and PTV8 radiomics models, with C-indexes of 0.750 and 0.703 in the training and validation cohorts, respectively. The nomogram was constructed by integrating the GTV radiomics signature, PTV4 radiomics signature, and relevant clinical characteristics, including CA19-9 level, clinical T stage, and clinical N stage. The nomogram achieved C-indexes of 0.831 and 0.748, with corresponding AUCs of 0.872 and 0.808 for 5-year DMFS in the training and validation cohorts, respectively. Kaplan-Meier analysis revealed that a cut-off value of 1.653 effectively stratified patients into high- and low-risk groups for DM (P < 0.001).

CONCLUSION

The intra-peritumoral radiomics nomogram is a favorable tool for clinicians to develop personalized systemic treatment and intensive follow-up strategies to improve patient prognosis.

Current perspectives on the management of lateral pelvic lymph nodes in rectal cancer

Significant controversies exist with regards to the optimal management of lateral pelvic lymph nodes metastases (mLLN) in patients with low rectal cancer. The differing views held by Japanese and Western clinicians on the management of mLLN have been well documented. However, the adequacy of pelvic lymph node dissection (PLND) or neoadjuvant chemoradiation (NACRT) alone in addition to total mesorectal excision (TME) have recently come into question, due to the relatively high incidence of lateral local recurrences following PLND and TME, or NACRT and TME alone. Recently, a more selective approach to PLND has been suggested, involving a combination of neoadjuvant therapy, followed by PLND only to patients in whom the oncological benefit is likely to outweigh the risk of potential adverse events. A number of studies have attempted to retrospectively identify certain nodal characteristics on preoperative imaging, such as nodal size, appearance, and size reduction following neoadjuvant therapy. However, no consensus has been reached regarding the optimal criteria for a selective approach to PLND, partly due to the heterogeneity and retrospective nature of most of these studies. This review aims to provide an overview of recent evidence with regards to the diagnostic challenges, considerations for, and outcomes of the current management strategies for mLLN in rectal cancer patients.

Is Nonoperative Management of Rectal Cancer Feasible?

During the past decade, the treatment of locally advanced rectal cancer (LARC) has become more complex. Total neoadjuvant treatment (TNT) has increased the rates of both clinical and pathologic complete response, resulting in improved long-term oncological outcomes. The feasibility to implement nonoperative management (NOM) depends on solving current challenges such as how to correctly identify the best candidates for a NOM without compromising oncologic safety. NOM should be part of the treatment discussion of LARC, considering increasing rates of clinical complete response, potential quality of life gains, avoidance of surgical morbidity, and patient preferences.

Evaluation of National Surgical Practice for Lateral Lymph Nodes in Rectal Cancer in an Untrained Setting

BACKGROUND

Involved lateral lymph nodes (LLNs) have been associated with increased local recurrence (LR) and ipsi-lateral LR (LLR) rates. However, consensus regarding the indication and type of surgical treatment for suspicious LLNs is lacking. This study evaluated the surgical treatment of LLNs in an untrained setting at a national level.

METHODS

Patients who underwent additional LLN surgery were selected from a national cross-sectional cohort study regarding patients undergoing rectal cancer surgery in 69 Dutch hospitals in 2016. LLN surgery consisted of either 'node-picking' (the removal of an individual LLN) or 'partial regional node dissection' (PRND; an incomplete resection of the LLN area). For all patients with primarily enlarged (≥7 mm) LLNs, those undergoing rectal surgery with an additional LLN procedure were compared to those  undergoing only rectal resection.

RESULTS

Out of 3057 patients, 64 underwent additional LLN surgery, with 4-year LR and LLR rates of 26% and 15%, respectively. Forty-eight patients (75%) had enlarged LLNs, with corresponding recurrence rates of 26% and 19%, respectively. Node-picking (n = 40) resulted in a 20% 4-year LLR, and a 14% LLR after PRND (n = 8; p = 0.677). Multivariable analysis of 158 patients with enlarged LLNs undergoing additional LLN surgery (n = 48) or rectal resection alone (n = 110) showed no significant association of LLN surgery with 4-year LR or LLR, but suggested higher recurrence risks after LLN surgery (LR: hazard ratio [HR] 1.5, 95% confidence interval [CI] 0.7-3.2, p = 0.264; LLR: HR 1.9, 95% CI 0.2-2.5, p = 0.874).

CONCLUSION

Evaluation of Dutch practice in 2016 revealed that approximately one-third of patients with primarily enlarged LLNs underwent surgical treatment, mostly consisting of node-picking. Recurrence rates were not significantly affected by LLN surgery, but did suggest worse outcomes. Outcomes of LLN surgery after adequate training requires further research.

Restaging rectal cancer following neoadjuvant chemoradiotherapy

Correct tumour restaging is pivotal for identifying the most personalised surgical treatment for patients with locally advanced rectal cancer undergoing neoadjuvant therapy, and works to avoid both poor oncological outcome and overtreatment. Digital rectal examination, endoscopy, and pelvic magnetic resonance imaging are the recommended modalities for local tumour restaging, while chest and abdominal computed tomography are utilised for the assessment of distant disease. The optimal length of time between neoadjuvant treatment and restaging, in terms of both oncological safety and clinical effectiveness of treatment, remains unclear, especially for patients receiving prolonged total neoadjuvant therapy. The timely identification of patients who are radioresistant and at risk of disease progression remains challenging.

Difference in prognostic impact of lateral pelvic lymph node metastasis between pre- and post-neoadjuvant chemoradiotherapy in rectal cancer patients

Purpose

The prognostic significance and treatment of lateral pelvic lymph node metastasis (mLPLN) in rectal cancer patients receiving neoadjuvant chemoradiotherapy (nCRT) are not well understood. In this study, we evaluated the impact of mLPLN identified in imaging modality on outcomes.

Methods

Between January 2008 and December 2016, 1,535 patients who underwent radical resection following nCRT were identified. The association between mLPLN and disease-free survival (DFS), overall survival (OS), local recurrence-free survival (LRFS), and pelvic recurrence-free survival (PRFS) was analyzed, along with risk factors associated with OS and DFS.

Results

Overall, 329 (21.4%) of the 1,535 patients experienced disease recurrence; 71 (4.6%) had local recurrence, 25 (1.6%) had pelvic recurrence, and 312 (20.3%) had distant recurrence. The pre- and post-nCRT mLPLN (-) groups had better DFS, LRFS, PRFS, and OS than the (+) groups. LPLN sampling (LPLNs) was implemented in 24.0% of the pre-nCRT mLPLN (+) group and in 28.8% of the post-nCRT mLPLN (+) group. There was no significant difference in OS and LRFS between LPLNs group and no LPLNs group in pre- and post-nCRT mLPLN (+) groups. Pre-nCRT mLPLN was associated with poor OS (hazard ratio [HR], 1.43; P = 0.009) and post-nCRT mLPLN was associated with poor DFS (HR, 1.49; P = 0.002).

Conclusion

Pre- and post-nCRT mLPLN (+) have different prognostic effects. Post-nCRT mLPLN appears to be more important for disease control. However, pre-nCRT mLPLN should not be disregarded when devising a treatment strategy since it is an independent risk factor for OS.

Non-Operative Management of Patients with Rectal Cancer: Lessons Learnt from the OPRA Trial

Over the past decade, the management of locally advanced rectal cancer (LARC) has progressively become more complex. The introduction of total neoadjuvant treatment (TNT) has increased the rates of both clinical and pathological complete response, resulting in excellent long-term oncological outcomes. As a result, non-operative management (NOM) of LARC patients with a clinical complete response (cCR) after neoadjuvant therapy has gained acceptance as a potential treatment option in selected cases. NOM is based on replacement of surgical resection with safe and active surveillance. However, the identification of appropriate candidates for a NOM strategy without compromising oncologic safety is currently challenging due to the lack of an objective standardization. NOM should be part of the treatment plan discussion with LARC patients, considering the increasing rates of cCR, patient preference, quality of life, expectations, and the potential avoidance of surgical morbidity. The recently published OPRA trial showed that organ preservation is achievable in half of rectal cancer patients treated with TNT, and that chemoradiotherapy followed by consolidation chemotherapy may an appropriate strategy to maximize cCR rates. Ongoing trials are investigating optimal algorithms of TNT delivery to further expand the pool of patients who may benefit from NOM of LARC.

The awareness of radiologists for the presence of lateral lymph nodes in patients with locally advanced rectal cancer: a single-centre, retrospective cohort study

Objectives

Enlarged lateral lymph nodes (LLNs) are associated with increased (lateral) local recurrence rates. Size and anatomical location should therefore always be reported by radiologists and discussed during multidisciplinary meetings. The objective was to investigate how often LLNs are mentioned in MRI reports in a tertiary referral centre.

Methods

A single - centre, retrospective study of 202 patients treated for primary rectal cancer between 2012 and 2020, with at least a T2 tumour located within 12cm of the anorectal junction. The radiology reports were written by 30–40 consultant radiologists. MRI scans were independently re-assessed by an expert radiologist. The primary outcome was how often the presence or absence of LLNs was mentioned in the initial report.

Results

Primary MRI reports explicitly mentioned the presence or absence of LLNs in 89 (44%) cases. Of the 43 reports with present LLNs, only one (1%) reported on all features such as size, location or malignant features. Expert review revealed 17 LLNs which were ≥ 7 mm (short-axis); two of these were not mentioned in the original reports. In 14/43 (33%) cases, LLNs were discussed during the primary multidisciplinary meeting, while 17/43 (40%) restaging MRI reports failed to report on the previously visible LLN. Reporting LLNs increased significantly with higher N-stage (p = .010) and over time (p = .042).

Conclusions

Though improving with time, there is still limited consistency in reporting LLNs. Only 44% of primary MRI reports mentioned LLNs and relevant features of those LLNs were seldomly reported. Given the importance of this information for subsequent treatment; increased awareness, proper training and the use of templates are needed.

Key Points

• Comprehensive reporting of lateral lymph nodes in primary MRI reports was limited to less than 50%.

• Lateral lymph nodes are not always discussed during primary multidisciplinary meetings or mentioned in restaging reports.

• Improvements in the awareness and knowledge of lateral lymph nodes are needed to ensure adequate multidisciplinary treatment decisions.

Nonoperative Management for Rectal Cancer

The treatment algorithm for locally advanced rectal cancer (LARC) has increased in complexity over the past 10 years. Nonoperative management (NOM) for rectal cancer in patients with clinical complete response (cCR) after neoadjuvant therapy has been gaining acceptance as a potential treatment option for selected LARC patients. The current challenge is to accurately select the patients with an apparent cCR, thereby correctly identifying those would-be appropriate candidates for a NOM strategy. NOM should be part of the treatment discussion of LARC, considering increasing rates of cCR, patient preference, potential quality of life gains, and the potential avoidance of surgical morbidity.

Current practices concerning the assessment and treatment of lateral lymph nodes in low rectal cancer: a survey among colorectal surgeons in The Netherlands

PURPOSE

The presence of lateral lymph nodes (LLNs) in patients with rectal cancer is not always acknowledged by the multidisciplinary team or treated in a standardized manner, and (inter)national guidelines concerning this topic are lacking. This study aimed to evaluate current practices regarding the assessment and treatment of LLNs in rectal cancer patients based on a survey among Dutch colorectal surgeons.

METHODS

An online survey was sent to members of the Dutch Association of Coloproctology. The survey consisted of 16 questions addressing their views on diagnosis, restaging, and treatment approaches for suspicious LLNs.

RESULTS

A total of 62 surgeons from 50 Dutch hospitals responded. For patients with a distal cT3/T4 rectal tumor; lateral lymph node compartments were routinely discussed during multidisciplinary meetings in only nine hospitals (18%). When defining what makes an LLN suspicious; the size threshold varied from >3 to >10 mm (median 7, SD 2), and MRI-based malignant features were mentioned by 29 surgeons (47%). Surgeons stated eight different treatment strategies as their designated treatment of suspicious LLNs. A total of 33 surgeons (53%) would add a radiotherapy boost to the neoadjuvant treatment. In cases of surgical resection; 12 surgeons (19%) would remove the suspicious LLN by 'node-picking' and 44 surgeons (71%) would perform a lateral lymph node dissection. The variation was not influenced by hospital type or surgeon's experience.

CONCLUSION

These results highlight the vast variation in the awareness, definition of suspicious LLNs in rectal cancer, and different treatment approaches. International guidelines based on further research are warranted.

Lateral lymph node dissection in rectal cancer: State of the art review

Half of the local regional recurrences from rectal cancer are nowadays located in the lateral compartments, most likely due to lateral lymph node (LLN) metastases. There is evidence that a lateral lymph node dissection (LLND) can lower the lateral local recurrence rate. An LLND without neoadjuvant (chemo)radiotherapy in patients with or without suspected LLN metastases has been the standard of care in the East, while Western surgeons believed LLN metastases to be cured by neoadjuvant treatment and total mesorectal excision (TME) only. An LLND in patients without enlarged LLNs might result in overtreatment with low rates of pathological LLNs, but in patients with enlarged LLNs who are treated with (C)RT and TME only, the risk of a lateral local recurrence significantly increases to 20%. Certain Eastern and Western centers are increasingly performing a selective LLND after neoadjuvant treatment in the presence of suspicious LLNs due to new scientific insights, but (inter)national consensus on the indication and surgical approach of LLND is lacking. An LLND is an anatomically challenging procedure with intraoperative risks such as bleeding and postoperative morbidity. It is therefore essential to carefully select the patients who will benefit from this procedure and where possible to perform the LLND in a minimally invasive manner to limit these risks. This review gives an overview of the current evidence of the assessment of LLNs, the indications for LLND, the surgical technique, pitfalls in performing this procedure and the future studies are discussed, aiming to contribute to more (inter)national consensus.

From "East vs West" towards international multidisciplinary collaboration: An appraisal of lateral lymph nodes in rectal cancer

Western and Eastern practices have traditionally differed in their approach to treating lateral lymph nodes in rectal cancer. While Western clinicians have primarily favored neoadjuvant (chemo)radiotherapy to sterilize lateral compartments, Eastern physicians have often opted for the surgical removed of lymphatic tissue with a lateral lymph node dissection without neoadjuvant treatment. The literature suggests similar oncological outcomes for these two separate techniques, while tangible differences exist. The combination of these paradigms may be beneficial in reducing overall morbidity while sustaining low recurrence rates. This article considers traditional Eastern and Western perspectives, discusses nodal features important for predicting malignancy and attempts to stimulate international, multidisciplinary consensus and collaboration.