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Oncological Impact of Lateral Nodes in Rectal Cancer

ABSTRACT: The combination of neoadjuvant chemoradiotherapy (CRT) and total mesorectal excision (TME) is considered the standard treatment for locally advanced rectal cancer in the western world. Appropriate preoperative treatment and margin free surgery are key-elements in reducing the local-recurrence of the tumor and consequently improving overall survival. Nevertheless, the local recurrence of stage II and III rectal cancer is still high, with current levels of 5% to 10% even when R0 resection is achieved. Most of the cases of loco-regional recurrence are associated with lateral lymph nodes (LLN) spread of cancer cells, which is not always controlled by the preoperative chemotherapy. As a matter of fact, the incidence of LLD metastases has been estimated to range from 11% to 22% in patients with T3/4 rectal cancer below the peritoneal reflection. In order to improve these poor outcomes, Japanese surgeons have adopted extended lymphadenectomy with the dissection of lateral extramesorectal lymph nodes as the standard of care for T2-3 low rectal cancer patients5. While this approach is widely used in Japan and Korea, western surgeons have preferred a less aggressive approach, indicating lateral lymph node dissection (LLND) only in presence of clinically highly suspicious lateral pelvic lymph nodes on baseline magnetic resonance imaging (MRI). Thus, it is essential to identify preoperative predictive factors of LLN metastasis. Even if MRI is considered the optimal diagnostic tool in rectal cancer, its accuracy for LLN staging is considered poor, especially after neoadjuvant treatment. LLNs often change in both features and size after CRT, and this behaviour might not be in concordance with the response of the primary tumor. To the best of our knowledge, no consensus exists on whether the risk of local recurrence should be determined by assessing the features of LLN on the primary MRI or on the restaging MRI. Moreover, the relation between LLN response and primary tumor regression grade after neoadjuvant CRT needs to be thoroughly explored. This multicenter cohort study aimed to investigate factors on primary and restaging MRI associated with lateral nodal recurrence and to identify patients who may benefit from LLND after neoadjuvant treatment for locally advanced rectal cancer.

DISEASE(S): Colorectal Adenocarcinoma,Rectal Neoplasms

PROVIDER: 2752396 | ecrin-mdr-crc |

REPOSITORIES: ECRIN MDR

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Project description:Importance: Neoadjuvant chemoradiotherapy (CRT) is the standard of care for advanced rectal cancer. Yet, predicting response to CRT remains an unmet clinical challenge. Objective: To investigate the transcriptomic determinants to predict response to neoadjuvant CRT and survival in patients with advanced rectal cancer. Design: A single-center, retrospective, cohort study. Setting: A comprehensive cancer center. Participants: Pre-treatment biopsies from 298 patients with rectal cancer, who were later treated with neoadjuvant CRT between 2004 and 2020, were analyzed by RNA sequencing. Main measures and outcomes: Transcriptional subtyping was performed by consensus molecular subtype (CMS) classification. Immune cell infiltration was assessed using MCP-counter scores and single-sample gene set enrichment analysis (ssGSEA). Patients with surgical specimens of tumor regression grade (TRG) 3-4 or who were managed by the watch-and-wait approach for more than 3 years were defined as good responders. Results: Patients classified as CMS1 (6.4%) had a significantly higher rate of good responders; albeit survival was comparable among the four subtypes. Good responders exhibited an enrichment in various immune-related pathways (IFNg and a responses, allograft rejection, IL6 STAT3 signaling during acute phase response, and inflammation), as determined by ssGSEA. MCP-counter scores for cytotoxic lymphocytes were significantly higher for good responders than non-responders (p = 0.0003), and significantly higher for responders than non-responders in GSE109057 (p = 0.0137), GSE87211 (p = 0.0092), and GSE45404 (p = 0.0327) datasets. Cytotoxic lymphocyte MCP-counter score was thus considered an independent predictor of response to CRT, as determined in the multivariable Cox analysis (OR 3.810 [95% CI 1.820-7.970]; p = 0.0004). Multivariable Cox analysis, including post-operative pathological factors, revealed cytotoxic lymphocyte MCP-counter score to be independently associated with recurrence-free survival (HR 0.382 [95% CI 0.158-0.923]; p = 0.0325) and overall survival (HR 0.157 [95% CI 0.030-0.827]; p = 0.0290). ssGSEA showed significantly higher levels of four subpopulations of cytotoxic cells (effector memory CD8 T, natural killer T, natural killer, and activated CD8 T cells) among good responders than non-responders. Conclusions and Relevance: Cytotoxic lymphocyte score, as computed by RNA sequencing, could be a useful marker for predicting response to CRT and survival among patients with rectal cancer.

Project description:Background: While much progress has been accomplished in the understanding of radiation-induced immune effects in tumors, little is known regarding the mechanisms involved at the tumor draining lymph node (TDLN) level following tumor irradiation. The objective of this retrospective study was to assess the immune and biological changes arising in TDLN upon concurrent chemoradiotherapy of primary non-small cell lung cancer (NSCLC) tumors. Methods: Patients with proved localized (cN0M0) NSCLC, treated by radical surgery plus lymph node dissection with (CRT+) or without (CRT-) neoadjuvant chemoradiotherapy, whereby radiotherapy was targeted on the primary tumor with no significant incidental irradiation of the TDLN station (stations XI or X), were identified. Bulk RNA-Seq of TDLNs was performed and data were analyzed based on differential gene expression (DEG) and gene sets enrichment. Results: Sixteen patients were included and 25 TDLNs were analyzed: 6 patients in the CRT+ group (12 samples) and 10 patients in the CRT- group (13 samples). Overall, 1001 genes were differentially expressed between the two groups (CRT+ and CRT-). Analysis with g-profiler revealed that gene sets associated with antitumor immune response, inflammatory response, hypoxia, angiogenesis, epithelial mesenchymal transition and extra-cellular matrix remodeling were enriched in the CRT+ group, whereas only gene sets associated with B cells and B-cell receptor signaling were enriched in the CRT- group. Unsupervised dimensionality reduction identified two clusters of TDLNs from CRT+ patients, of which one cluster (cluster 1) exhibited higher expression of pathways identified as enriched in the overall CRT+ group in comparison to the CRT- group. In CRT+ cluster 1, 3 out of 3 patients had pathological complete response (pCR) or major complete response (MPR) to neoadjuvant CRT, whereas only 1 out of 3 patients in the other CRT+ cluster (cluster 2) experienced MPR and none exhibited pCR. Finally, pathway comparison to published data from pre-metastatic TDLNs uncovered similarities with CRT+ cluster 1. Conclusion: Neoadjuvant concurrent chemoradiotherapy of the primary tumor in N0 NSCLC patients is associated with distinct microenvironment and immunological patterns in TDLNs as compared to TDLNs from patients with non-irradiated tumors. Our data are in line with studies showing superiority of lymph node sparing irradiation of the primary tumor in the induction of systemic antitumor immunity.

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Oncological Impact of Lateral Nodes in Rectal Cancer

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