Molecular Basis of Extramural Vascular Invasion (EMVI) in Colorectal Carcinoma

Predictors of Pathologic Non-response to Neoadjuvant Approaches in Locally Advanced Rectal Cancer

BACKGROUND

Approximately 10-20% of rectal cancer patients do not respond to neoadjuvant treatment. While the current literature has focused on pathological complete response, pinpointing those who will fail to benefit entirely from neoadjuvant approaches is crucial.

OBJECTIVE

This study aimed to determine the risk factors associated with pathological non-response (pNR) to neoadjuvant treatment.

METHODS

Patients with stage II-III rectal adenocarcinoma who underwent neoadjuvant treatment followed by curative surgical resection between 2018 and 2023 at a high-volume center were retrospectively reviewed. Patients were divided into two cohorts (pNR and pathologic responder [pR]) based on their response to neoadjuvant therapy. The pNR group included patients with a Tumor Regression Score of grade 3 or those upstaged on the final pathological report.

RESULTS

Of the 405 patients included in this study, 53 (13%) were pNR and 352 (87%) were pR. Among patients treated with standard neoadjuvant chemoradiation, 12% were pNR compared with 14% among those treated with total neoadjuvant therapy. Significantly more patients in the pNR cohort had perineural (31% vs. 8%; p < 0.001) and lymphovascular (22% vs. 6%, p = 0.001) invasions when compared with the pR cohort. After adjusting for age, sex, clinical T stages, and clinical nodal status on multivariable analysis, the presence of extramural vascular invasion (EMVI) on pretreatment magnetic resonance imaging (odds ratio 2.08, 95% confidence interval 1.03-4.20, p = 0.04) was identified as a significant predictor of pNR.

CONCLUSION

EMVI was an independent risk factor of pNR in patients with rectal cancer. Identifying pretreatment factors that predict pNR to neoadjuvant therapy is crucial as it allows for better risk stratification and personalized treatment strategies.

Overall survival prediction of gastric cancer using the gene signature of CT-detected extramural venous invasion combined with M2 macrophages infiltration

BACKGROUND

CT-detected Extramural venous invasion (EMVI) is known as an independent risk factor for distant metastasis in patients with advanced gastric cancer (GC). However, the molecular basis is not clear. In colorectal cancer, M2 macrophages plays a vital role in determining EMVI. This study aimed to investigate the relationship between CT-detected EMVI and the M2 macrophages as well as prognosis predictionusing a radiogenomic approach.

METHOD

We utilized EMVI-related genes (from mRNA sequencing of 13 GC samples correlated with EMVI score by spearman analysis, P < 0.01) to overlap the co-expression genes of WGCNA module and M2 macrophages related genes (from mRNA data of 371 GC patients in TCGA database), generating a total of 136 genes. An EMVI-M2-prognosis-related hub gene signature was constructed by COX and least absolute shrinkage and selection operator (LASSO) analysis from a training cohort TCGA database (n = 371) and validated it in a validation cohort from GEO database (n = 357). High- and low-risk groups were divided by hub gene (EGFLAM and GNG11) signature-derived risk scores. We assessed its predictive ability through Kaplan-Meier (K-M) curve and COX analysis. Furthermore, we utilized ESTIMATE to detect tumor mutation burden (TMB) and evaluate sensitivity to immune checkpoint inhibitors (ICIs). Expression of hub genes was tested using western blotting and immunohistochemistry (IHC) analysis.

RESULTS

The overall survival (OS) was significantly reduced in the high-risk group (Training/Validation: AUC = 0.701/0.620; P < 0.001/0.003). Furthermore, the risk score was identified as an independent predictor of OS in multivariate COX regression analyses (Training/Validation: HR = 1.909/1.928; 95% CI: 1.225-2.974/1.308-2.844). The low-risk group exhibited significantly higher TMB levels (P = 1.6e- 07) and greater sensitivity to ICIs. Significant higher expression of hub-genes was identified on multiple GC cell lines and original samples. Hub-genes knockdown in gastric cancer cell lines inhibited their proliferation, metastatic and invasive capacity to varying degrees. In vivo experiments indicate that EGFLAM, as one of the hub genes, its high expression can serve as a biomarker for low response to immunotherapy.

CONCLUSION

Our study demonstrated EMVI-M2 gene signature could effectively predict the prognosis of GC tissue, reflecting the relationship between EMVI and M2 macrophages.

Assessing venous invasion in stage II colon cancer: optimal elastin stains and survival analysis

AIMS

Venous invasion (VI) in colorectal carcinoma influences treatment strategies, especially in early stages. Despite elastin staining effectiveness in detecting VI, guidelines for its routine application, including the optimal number of slides for staining, are limited.

METHODS

Elastin staining was performed for VI assessment in patients with colorectal adenocarcinoma. Patients were categorised into two groups: single elastin stain group (SEG, n=248) and multiple elastin stain group (MEG, n=204).

RESULTS

The average number of elastin-stained blocks was 2±1.7, increasing to 3.3±1.9 in MEG. VI detection was significantly higher in patients in MEG (50.5%) compared with SEG (37.0%) (p=0.004). VI detection rate was higher in MEG (63.7%) than in SEG (46.0%) among patients with stage III-IV disease (p=0.011), but did not significantly differ among patients with stage I-II disease. Staining two blocks improved VI detection without additional gains from more stains. Compared with elastin performed on a single block, VI detected by elastin stain on two or more blocks did not significantly impact progression-free or disease-free survival with stage II patients.

CONCLUSIONS

Employing two elastin stains on separate blocks significantly enhances VI detection in colorectal carcinoma without additional benefits from more extensive staining. This study suggests that while increasing sensitivity for VI detection, staining beyond two blocks may not benefit prognostication and could be counterproductive, warranting further research. We emphasise the need for strategic use of the elastin stain and cautious interpretation of the increased detection sensitivity of multiple elastin stains.

Operative and Pathological Factors in Right-Sided Colon Cancers: How Can We Improve the Outcomes?

INTRODUCTION

Though the tumour-node-metastasis staging classification is the standard approach to risk stratification in patients with colorectal cancer, several other important variables including the presence of extramural venous invasion (EMVI), the tumour mismatch repair status, as well as surgical technique and its influence on lymph node yield all have an impact on long-term survival. This study aims to review both the impact of the type of operation on lymph node yield: complete mesocolic excision (CME) versus right hemicolectomy, and the impact of EMVI and microsatellite instability in predicting overall survival in patients undergoing a right hemicolectomy for colon cancer.

METHODS

Data of all patients who underwent an elective or emergency right hemicolectomy with curative intent for colon cancer between January 2013 and June 2022 (inclusive) was collected for this single-centre retrospective study. Kaplan-Meier survival curves were calculated using the Statistical Package for the Social Sciences (SPSS version 28, IBM Corp., Armonk, NY) software, and the log-rank (Mantel-Cox) test was used to compare survival distribution between different groups.

RESULTS

A total of 421 patients underwent a right hemicolectomy for colon cancer with curative intent during the study period. EMVI was present in 173 (41%) tumours. Survival analysis showed significantly reduced cancer-related survival in patients with EMVI-positive tumours (p < 0.001), with five-year survival rates of 70% in EMVI-positive groups versus 96% in EMVI-negative groups. Subgroup analysis showed a significant difference in survival between node-positive and node-negative tumours in cancers found to have EMVI (p < 0.001). Mean lymph node yield was significantly higher in the CME group versus the standard right hemicolectomy group (p < 0.001). We found no significant difference in survival between patients with microsatellite instability-high (MSI-H) tumours and microsatellite stable (MSS) tumours (p = 0.432).

CONCLUSION

Consideration of tumour biology and adopting the optimum surgical technique are factors that may influence long-term survival in patients with colorectal cancer. Extramural venous invasion is an important prognostic indicator of adverse outcomes in patients with right-sided colon cancer. Our study demonstrates a reduction in survival in patients with EMVI-positive tumours when undertaking subgroup analysis by the presence or absence of nodal disease. Further research needs to be undertaken to compare the relative efficacy of neoadjuvant versus adjuvant chemotherapy in right-sided cancers known to be EMVI-positive as some patients will fail to have adjuvant chemotherapy due to postoperative complications, thereby delaying recovery and missing the optimum window for treatment.