Prognostic Impact of Extramural Lymphatic, Vascular, and Perineural Invasion in Stage II Colon Cancer: A Comparison With Intramural Invasion

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.

The depth of perineural invasion is an independent prognostic factor for stage II colorectal cancer

BACKGROUND

Perineural invasion (PNI) is the invasion of nerves by cancer cells and is associated with poor survival in stage II colorectal cancer. However, PNI can be further subdivided according to the depth of invasion, and the depth of PNI has not been clearly linked to prognosis.

METHOD

This study aimed to assess the prognostic value of different depths of PNI in stage II colorectal cancer. We defined PNI in the submucosal plexus and myenteric plexus as superficial perineural invasion (sup-PNI) and PNI in the subserous plexus as deep perineural invasion (deep-PNI). Patients were divided into three groups based on the depth of PNI: sup-PNI, deep-PNI and non-PNI. Then, univariate and multivariate Cox regression analyses were conducted to evaluate the role of PNI in the prognosis of stage II colorectal cancer.

RESULTS

This study enrolled 3508 patients with stage II colorectal cancer who underwent resection for primary colorectal lesions between January 2013 and September 2019. Clinicopathological features, including elevated carcinoembryonic antigen (CEA) levels, T4 stage, poor differentiation, deficient DNA mismatch repair (dMMR), and vascular invasion, were correlated with deep-PNI. Multivariate analyses revealed that deep-PNI was associated with worse overall survival (OS; hazard ratio [HR], 3.546; 95% confidence interval [CI], 2.307-5.449; P < 0.001) and disease-free survival (DFS; HR, 2.921; 95% CI, 2.032-4.198; P < 0.001), compared with non-PNI. Conversely, no significant difference in OS or DFS was observed between the sup-PNI and non-PNI groups in multivariate analyses.

CONCLUSIONS

The study demonstrated that the depth of PNI was an independent prognostic factor for patients with stage II colorectal cancer, and patients with deep PNI had a worse prognosis. Thus, patients with PNI require further subdivision according to the depth of invasion.

Prognostic Analysis of Lymphovascular Invasion in Stages I-III Colorectal Cancer: A Retrospective Study Based on Propensity Score Match

INTRODUCTION

Lymphovascular invasion (LVI) is a micropathological tumor factor believed to increase the risk of tumor metastasis and spread. Propensity score matching (PSM) is a statistical method that can control confounding factors. Current research rarely considers the confounding relationship between LVI and other factors that may influence prognosis. This study aimed to investigate the relationship between LVI and prognosis in patients with stage I-III colorectal cancer (CRC) by using propensity score matching (PSM).

METHODS

This was a retrospective study involving 610 patients. PSM was used to adjust for baseline differences between the groups. The survival rates were calculated. A nomogram was constructed based on the Cox proportional hazards model before matching. The C-index, receiver operating characteristic curve (ROC), and calibration curve were used to evaluate the nomogram.

RESULTS

A total of 150 patients tested positive for LVI, accounting for 24.6% of the total, and 120 couples of patients were identified after PSM. The survival curve and Cox proportional hazards model after matching confirmed the adverse effects of LVI on tumor prognosis. The Cox proportional hazards model before matching showed that age, carcinoembryonic antigen level, T stage, N stage, histologic grade and LVI were independent prognostic factors. The C-index of the nomogram established based on the Cox proportional hazards model was 0.787 (95% CI=0.728-0.845). The areas under the curve were 0.796 in the 3-year ROC.

CONCLUSIONS

LVI is an adverse prognostic factor in patients with stage I-III colorectal cancer.

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.