Lymphovascular Infiltration, Not Depth of Invasion, is the Critical Risk Factor of Metastases in Early Colorectal Cancer: Retrospective Population-based Cohort Study on Prospectively Collected Data, Including Validation

The Potential Health Economic Value of Adding Magnetomotive Ultrasound to Current Diagnostic Methods for Detecting Lymph Node Metastases in Rectal Cancer

BACKGROUND

Local resection of early rectal cancer (RC) is a desirable treatment option compared with surgery, offering reduced morbidity, mortality, health care costs and avoidance of stoma. However, local resection is restricted to cases without suspicion of lymph node metastases (LNM). Current methods to diagnose LNM and risk estimations based on histopathology cannot reliably identify patients eligible for local resection. The NanoEcho diagnostic system is based on a novel method for lymph node staging in RC. The aim of this study was to perform a health economic analysis at an early stage of clinical development to estimate the potential value of adding NanoEcho diagnostics to current diagnostic methods in RC.

METHODS

A Markov model for RC diagnosis was developed where the costs and health outcomes, including quality-adjusted life years (QALYs), for adding the NanoEcho diagnostics to current diagnostic methods were compared with current diagnostic methods alone. The diagnostic performance of the NanoEcho diagnostic system is still unknown and the base-case analysis was performed at an assumed 85% sensitivity and 85% specificity. Two testing strategies corresponding to two alternative ways of implementing the diagnostic test in clinic were evaluated: (1) examine all patients diagnosed with RC and (2) examine only patients diagnosed with clinical stages T1 and T2.

RESULTS

Adding the NanoEcho diagnostic system resulted in a gain of 0.032 life years and 0.124 QALYs per patient in the target population compared with current diagnostic methods alone. At a cost-neutral level, the estimated justifiable price of NanoEcho diagnostics was SEK 6995 in the first testing strategy and SEK 50,658 in the second testing strategy. The justifiable price of the NanoEcho diagnostics at a willingness to pay of 500,000 SEK/QALY was SEK 10,654 in the first testing strategy and SEK 65,132 in the second testing strategy.

CONCLUSION

The results indicate that adding NanoEcho diagnostics to standard of care can potentially reduce healthcare costs and increase quality of life in RC patients, assuming a sensitivity and specificity of 85%.

Improving radiologists' diagnostic accuracy for lymphovascular invasion in colorectal cancer: insights from a multicenter CT-based study

BACKGROUND

The current standard of subjective assessment by radiologists for lymphovascular invasion (LVI) in colorectal cancer (CRC) using CT images often falls short in diagnostic accuracy. This study introduces an advanced CT-based prediction model aimed at providing support for radiologists' assessment to accurately diagnose LVI.

METHODS

We conducted a retrospective analysis of 1409 patients with pathologically confirmed CRC from four institutions. Radiomics features were extracted from tumor areas on CT images, and Deep Residual Shrinkage Networks with Channel-wise Thresholds (DRSN-CW) algorithm was utilized to build prediction model. We assessed the model's impact on enhancing radiologists' diagnostic performance and employed Shapley Additive Explanation (SHAP) to interpret the influence of key features on predictions.

RESULTS

The prediction model achieved strong prediction performance with AUCs of 0.896 (95% CI: 0.866-0.923), 0.849 (0.782-0.908), 0.845 (0.782-0.901) and 0.799 (0.709-0.881) in the training and validation cohorts. Crucially, when informed by the model, radiologists demonstrated a significant improvement in diagnosing LVI. SHAP analysis provided detailed insights into the model's decision-making process, enhancing its clinical relevance. We also observed that patients predicted to be LVI-negative by the model had significantly longer overall survival (OS) compared to those LVI-positive (training cohort, p = 0.012; internal validation cohort, p = 0.046).

CONCLUSIONS

This study introduces a CT-based prediction model that significantly enhances radiologists' ability to accurately diagnose LVI in CRC. By improving diagnostic accuracy and demonstrating the association between LVI predictions and OS, the model provides a valuable tool for clinical decision-making, with the potential to improve patient outcomes.

Should endoscopic submucosal dissection be offered to patients with early colorectal cancer?

BACKGROUND

Endoscopic submucosal dissection is increasingly used to treat early-stage colorectal cancer. This study evaluated the feasibility of endoscopic submucosal dissection in this setting and the determinants of lymph node metastasis.

METHODS

We reviewed patients who underwent colorectal endoscopic submucosal dissection for early-stage colorectal cancer at a tertiary center between 2011 and 2023. The primary outcome was the identification of high-risk pathologic features predictive of lymph node metastasis in patients undergoing oncologic colon resection following endoscopic submucosal dissection.

RESULTS

We reviewed 1,398 patients who underwent endoscopic submucosal dissection, and 83 (6%) had colorectal cancer. Twenty-four patients (29%) were closely monitored after endoscopic submucosal dissection, and 59 (71%) underwent oncologic colon resection because of high-risk pathologies of the endoscopic submucosal dissection specimen. In the oncologic colon resection group, the mean age was 62.7 years (±10.2), with 56% male predominance, and 14% showed positive lymph nodes in the final pathology. Analysis comparing patients with and without lymph node metastasis showed significant differences in sex, lesion size, submucosal invasion depth, and budding scores. Multivariate analysis showed that lesions with a submucosal invasion depth ≥2.00 mm of the endoscopic submucosal dissection resection specimen had higher odds of lymph node metastasis (odds ratio 18.7, P = .028), whereas lesions with a diameter >20 mm were associated with a lower likelihood of lymph node metastasis (odds ratio 0.07, P = .036).

CONCLUSION

The study highlights the oncologic safety of early-stage endoscopic submucosal dissection as a viable treatment option for carefully selected patients with colorectal cancer. After tissue resection with endoscopic submucosal dissection, if the lesion size is less than 20 mm, depth of invasion up to 2 mm may be considered safe in the absence of other high-risk pathologic factors.

Preoperative prediction of multiple biological characteristics in colorectal cancer using MRI and machine learning

Colorectal cancer (CRC) is the second most prevalent cause of oncological mortality, and its diagnostic and therapeutic decision-making processes is complex. Alteration in molecular characteristic expression is closely related to tumor invasiveness and can serve a novel biomarker for predicting cancer prognosis. In this study, we aimed to construct radiomic models through machine learning to predict the progression of CRC. We collected the clinical, pathological, and magnetic resonance imaging (MRI) data of 136 CRC patients who underwent direct surgical resection. Immunohistochemistry analysis was performed to detect the expression levels of p53, synaptophysin (Syn), human epidermal growth factor receptor 2 (HER2), perineural invasion (PNI), and vascular invasion (VI) expression levels in CRC tissues. After the manual lesion segmentation, 1781 radiomics features were extracted from the transverse T2-weighted image of MRI (T2W-MRI). We employed Spearman's rank correlation coefficient, greedy recursive deletion strategy, minimum redundancy, maximum relevance, least absolute shrinkage, and selection operator regression were utilized to screen for radiological features. Radiomics and clinical models were constructed using the K-nearest neighbor (KNN). The diagnostic efficiencies of the prediction models were evaluated using receiver operating characteristic curves and quantified employing the area under the curve (AUC). Our research results indicate that compared with the single radioactive model, the clinical radiomics model in the validation cohort showed better diagnostic performance, as indicated by the AUC values (p53 = 0.758, Syn = 0.739, HER2 = 0.786, PNI = 0.835, VI = 0.797). Furthermore, the calibration curve and decision curve analyses showed the clinical benefits. In summary, we developed and validated a clinical radiomics model to preoperative prediction of the biological characteristic expression levels of CRC. The findings of this research may offer a promising noninvasive method for evaluating CRC risk stratification and may lay the groundwork for treatment of this disease.

Applicability of the Scottish screen-detected polyp cancer study (SSPoCS) algorithm in a multicentric cohort in the management of malignant colorectal polyps

BACKGROUND/OBJECTIVES

Robust evidence regarding the management after endoscopic resection of malignant colorectal polyps (MCP) is lacking. Inconsistencies in reporting on potential prognostic factors hinder the decision process. To address these issues, the Scottish Screen-detected Polyp Cancer Study (SSPoCS) introduced an algorithm based in two easily obtainable variables: resection margin and lymphovascular invasion. This study aims to assess the applicability of the SSPoCS algorithm in a Portuguese multicentric cohort.

METHODS

Endoscopically resected MCP in five centers were included. The main outcome was residual/recurrent malignancy (RRM), defined as any of the following: (1) residual intramural or lymph node malignancy in the surgical specimen after completion surgery; (2) local or systemic recurrent disease in conservatively managed patients.

RESULTS

Two-hundred and eleven patients were included (mean age: 68.6 ± 10.4 years; male participants: 65.4%); 121 underwent completion surgery while 90 remained in surveillance. Thirty-two patients (15.2%) experienced RRM: 27 displayed residual malignancy in the surgical specimen and five developed recurrent disease. According to the SSPoCS algorithm: 120 patients were classified as having low-risk of residual disease, six of whom displayed RRM (5.0%); 10 as medium-risk, with one having RRM (10.0%); and 81 as high-risk, 25 of whom experienced RRM (30.9%). Lesions classified as low risk showed a negative predictive value (NPV) of 95.0% to exclude RRM. The algorithm demonstrated good accuracy in predicting RRM in a Receiver Operating Characteristic curve analysis (AUC: 0.74; 95% CI: 0.65-0.83; p < 0.001).

CONCLUSIONS

The SSPoCS algorithm revealed good accuracy in predicting residual/recurrent malignancy with a NPV of 95.0% to exclude RRM in low-risk lesions.

Variation in the detection of lymphovascular invasion in T1 colorectal cancer and its impact on treatment: A nationwide Dutch study

BACKGROUND

Lymphovascular invasion (LVI) plays an important role in determining the risk of lymph node metastasis (LNM) in T1 colorectal cancer (CRC) patients and influencing treatment decisions and patient outcomes.

OBJECTIVE

This study evaluated how the detection of LVI varies between Dutch laboratories and investigated its impact on the treatment and oncological outcomes of T1 CRC patients.

METHODS

Pathology reports and clinical data of T1 CRC patients who underwent local resection between 2015 and 2019 were obtained from the Dutch nationwide pathology databank (Palga cohort, n = 5513). Data on the standard of LVI diagnosis (H&E/Immunohistochemistry) were not available. We categorized laboratories as low, average, or high detectors and evaluated the impact of LVI detection practice on the surgical resection rate and the proportion of LNM-negative (LNM-) surgeries. In the second part of the study, we used the Dutch T1 CRC Working Group cohort (n = 1268) to evaluate the impact of LVI detection practice on cancer recurrences during follow-up. Multivariable logistic regression analyses and Cox proportional hazard regression were used to study the association between LVI detection practice and the outcomes.

RESULTS

In the PALGA cohort, the proportion of surgical resections after local resection of a T1 CRC was significantly higher among patients diagnosed by laboratories with a high LVI detection rate (high vs. low: adjusted OR [aOR] 1.87; 95% confidence interval [CI] 1.52-2.31) as was the proportion of LNM-surgeries (aOR 1.73; 95% CI 1.39-2.15). In the second cohort, no significant difference was observed in cancer recurrences among patients diagnosed in laboratories with high detection rates compared with low detection rates (aHR 2.23; 95% CI 0.94-5.23).

CONCLUSION

These findings suggest that a high detection rate of LVI does not improve oncological outcomes and may expose more patients to unnecessary oncological surgery, emphasizing the need for standardization of LVI diagnosis.

Outcomes of noncurative endoscopic submucosal dissection for T1 colorectal cancer: Prospective, multicenter, cohort study in Japan

OBJECTIVES

This study investigated the incidence of lymph node metastasis and long-term outcomes in patients with T1 colorectal cancer where endoscopic submucosal dissection (ESD) resulted in noncurative treatment. It is focused on those with deep submucosal invasion, a factor considered a weak predictor of lymph node metastasis in the absence of other risk factors.

METHODS

This nationwide, multicenter, prospective study conducted a post-hoc analysis of 141 patients with T1 colorectal cancer ≥20 mm where ESD of the lesion resulted in noncurative outcomes, characterized by poor differentiation, deep submucosal invasion (≥1000 μm), lymphovascular invasion, high-grade tumor budding, or positive vertical margins. Clinicopathologic features and patient prognoses focusing on lesion sites and additional surgery requirements were evaluated. Lymph node metastasis incidence in the low-risk T1 group, identified by deep submucosal invasion as the sole high-risk histological feature, was assessed.

RESULTS

Lymph node metastasis occurred in 14% of patients undergoing additional surgery post-noncurative endoscopic submucosal dissection for T1 colorectal cancer. In the low-risk T1 group, in the absence of other risk factors, the frequency was 9.7%. The lymph node metastasis rates in patients with T1 colon and rectal cancers did not differ significantly (14% vs. 16%). Distant recurrence was observed in one patient (2.3%) in the ESD only group and in one (1.0%) in the additional surgery group, both of whom had had rectal cancer removed.

CONCLUSION

The risk of lymph node metastasis or distant occurrence was not negligible, even in the low-risk T1 group. The findings suggest the need for considering additional surgery, particularly for rectal lesions (Clinical Trial Registration: UMIN000010136).

The risk factors of lymph node metastasis in early colorectal cancer: a predictive nomogram and risk assessment

PURPOSE

Endoscopic procedures and surgery are common treatments for early colorectal cancer (CRC). However, only approximately 10% of patients who undergo surgery have lymph node metastases (LNM) detected on postoperative pathology, which often leads to overtreatment. This study aims to comprehensively analyze the risk factors for LNM in early CRC patients, establishing a predictive model to aid in treatment decisions.

METHODS

This study reviewed the clinicopathologic data of patients with early CRC who underwent surgery from January 2015 to June 2023. Univariate and multivariate logistic regression analyses were employed to identify LNM risk factors. The receiver operating characteristic (ROC) analysis and calibration curves were also constructed to verify the model's discrimination and calibration. A simplified scale was calculated to promote the risk stratification for LNM.

RESULTS

The study analyzed medical records of 375 patients. Of these, 37 (9.9%) cases had LNM. Univariate analysis identified age, nerve invasion, depth of submucosal invasion, histologic grade, LVI, and tumor budding as risk factors. The multivariate analysis confirmed histologic grade (OR, 13.403; 95% CI, 1.415-126.979; P = 0.024), LVI (OR, 6.703; 95% CI, 2.600-17.284; P < 0.001), and tumor budding (OR, 3.090; 95% CI, 1.082-8.820; P = 0.035) as independent predictors. The optimal nomogram, incorporating six risk factors, demonstrated strong predictability with an area under the ROC curve (AUC) of 0.837 (95% CI, 0.762-0.912). A simplified risk assessment scale with a total score of 19 points was developed.

CONCLUSION

The study developed a nomogram and a simplified risk assessment scale to predict LNM risk, potentially optimizing the management of early CRC patients.

Long-Term Follow-Up After Non-Curative Endoscopic Submucosal Dissection for Early Gastrointestinal Cancer-A Retrospective Multicenter Analysis

Background: Endoscopic Submucosal Dissection (ESD) has become the standard therapy for early malignant lesions in the gastrointestinal tract and has shown as good oncological surgery results. Approximately 30% of ESDs do not meet the criteria for oncological curability, and upfront surgery is indicated. Hence, about 40% of patients with an indication for surgery are advised against surgery because of comorbidities and an advanced age. Methods: We performed a multicenter retrospective cohort study on the long-term outcomes of non-curative ESDs, performed between 2009 and May 2024, without additional tumor therapy. The primary outcome was the recurrence of malignancy, either local malignancy or lymph node metastasis during follow-up, or death. We compared the outcomes between two cohorts: after non-curative ESD (ncESD) and after curative ESD (cESD). Results: A total of 374 ESDs were analyzed in this study. Overall, the technical success rate was 91%, and the oncological curative resection criteria were met in 70.9% of patients. Severe complications occurred in 5% of cases without procedure-associated mortality. In the ncESD group, 20% (7/35) of patients had a recurrence of malignancy primarily due to positive horizontal margins in the resection specimens, and 3 out of 35 died due to a non-oncological reason during the follow-up (mean length 36.6 months). In the cESD group, 3% (1/33) of patients had tumor recurrence, and 1 patient died because of a non-oncological reason. The tumor recurrence rate between the cohorts was significant (p = 0.017), and overall mortality did not show significance (p = 0.33). Conclusions: Especially in the elderly and multimorbid patients, the recommendation to perform rescue surgery after non-curative ESD remains challenging. Residual malignancy rates in surgical resection specimens are low, recurrence rates of malignancy are low, and mortality rates for non-oncological reasons are high in this population. There is a need for more data for the individualization of patient management after non-curative ESD.

Histological Risk Factors for Lymph Node Metastasis in pT1 Colorectal Cancer: Does Submucosal Invasion Depth Really Matter?

OBJECTIVE

After endoscopic resection of colorectal cancer with submucosal invasion (pT1 CRC), additional surgical treatment is recommended if deep submucosal invasion (DSI) is present. This study aimed to further elucidate the risk factors for lymph node metastasis (LNM) in patients with pT1 CRC, especially the effect of DSI on LNM.

METHODS

Patients with pT1 CRC who underwent lymph node dissection were selected. The Chi-square test and multivariate logistic regression were used to analyze the relationship between clinicopathological characteristics and LNM. The submucosal invasion depth (SID) was measured via 4 methods and analyzed with 3 cut-off values.

RESULTS

Twenty-eight of the 239 patients presented with LNM (11.7%), and the independent risk factors for LNM included high histological grade (P=0.003), lymphovascular invasion (LVI) (P=0.004), intermediate to high budding (Bd 2/3) (P=0.008), and cancer gland rupture (CGR) (P=0.008). Moreover, the SID, width of submucosal invasion (WSI), and area of submucosal invasion (ASI) were not significantly different. When one, two, three or more risk factors were identified, the LNM rates were 1.1% (1/95), 12.5% (7/56), and 48.8% (20/41), respectively.

CONCLUSION

Indicators such as the SID, WSI, and ASI are not risk factors for LNM and are subjective in their measurement, which renders them relatively inconvenient to apply in clinical practice. In contrast, histological grade, LVI, tumor budding and CGR are relatively straightforward to identify and have been demonstrated to be statistically significant. It would be prudent to focus on these histological factors rather than subjective measurements.

Clinicopathological and molecular differences between stage IV screen-detected and interval colorectal cancers in the Flemish screening program

Introduction

Interval cancer (IC) is an important quality indicator in colorectal cancer (CRC) screening. Previously, we found that fecal immunochemical test (FIT) ICs are more common in women, older age, right-sided tumors, and advanced stage. Here, we extended our existing stage IV patient cohort with clinicopathological and molecular characteristics, to identify factors associated with FIT-IC.

Methods

Logistic regression models were fit to identify variables associated with the odds of having a stage IV FIT-IC. Multivariate models were corrected for gender, age, and location.

Results

A total of 292 screen-detected (SD) CRCs and 215 FIT-IC CRCs were included. FIT-IC CRC had 5 fold higher odds to be a neuroendocrine (NET) tumor and 2.5 fold higher odds to have lymphovascular invasion. Interestingly, some variables lost significance upon accounting for location. Thus, tumor location is a critical covariate that should always be included when evaluating factors related to FIT-IC.

Conclusions

We identified NETs and lymphovascular invasion as factors associated with increased odds of having a stage IV FIT-IC. Moreover, we highlight the importance of tumor location as a covariate in evaluating FIT-IC related factors. More research across all stages is needed to clarify how these insights might help to optimize the Flemish CRC screening program.

Lymphovascular invasion is a dominant risk factor for lymph node metastasis in T2 rectal cancer

Background and study aims Surgical resection is standard treatment of T2 rectal cancer due to risk of concomitant lymph node metastases (LNM). Local resection could potentially be an alternative to surgical treatment in a subgroup of patients with low risk of LNM. The aim of this study was to identify clinical and histopathological risk factors of LNM in T2 rectal cancer. Patients and methods This was a retrospective registry-based population study on prospectively collected data on all patients with T2 rectal cancer undergoing surgical resection in Sweden between 2009 and 2021. Potential risk factors of LNM, including age, gender, resection margin, lymphovascular invasion (LVI), histologic grade, mucinous cancer, and perineural invasion (PNI) were analyzed using univariate and multivariate logistic regression. Results Of 1607 patients, 343 (21%) with T2 rectal cancer had LNM. LVI (odds ratio [OR] = 4.21, P < 0.001) and age < 60 years (OR = 1.80, P < 0.001) were significant and independent risk factors. However, PNI (OR = 1.50, P = 0.15), mucinous cancer (OR = 1.14, P = 0.60), histologic grade (OR = 1.47, P = 0.07) and non-radical resection margin (OR = 1.64, P = 0.38) were not significant risk factors for LNM in multivariate analyses. The incidence of LNM was 15% in the absence of any risk factor. Conclusions This was a large study on LNM in T2 rectal cancer which showed that LVI is the dominant risk factor. Moreover, low age constituted an independent risk factor, whereas gender, resection margin, PNI, histologic grade, and mucinous cancer were not independent risk factors of LNM. Thus, these findings may provide a useful basis for management of patients after local resection of early rectal cancer.

Endoscopic removal of gastrointestinal lesions by using third space endoscopy techniques

The concept of submucosal space, or rather the "third space", located between the intact mucosal flap and the muscularis propria layer of the gastrointestinal tract, represents a tunnel that the endoscopist could use to perform interventions in the muscularis propria layer or breech it to enter the mediastinum or the peritoneal cavity without full thickness perforation. The tunnel technique can be used both for the removal of mucosal tumours, called endoscopic submucosal tunnel dissection (ESTD), for the removal of subepithelial tumours (SELs), called submucosal tunnelling endoscopic resection (STER), and for the removal of extra-luminal lesions (for example in the mediastinum or in the rectum), called submucosal tunnelling endoscopic resection for extraluminal tumours (STER-ET). Aim of this updated narrative review, is to summarize the evidences that analyses indications, and outcomes of tunnelling techniques for the treatment of above mentioned lesions.

Predictors of early colorectal cancer metastasis to lymph nodes: providing rationale for therapy decisions

With the improvement of national health awareness and the popularization of a series of screening methods, the number of patients with early colorectal cancer is gradually increasing, and accurate prediction of lymph node metastasis of T1 colorectal cancer is the key to determining the optimal therapeutic solutions. Whether patients with T1 colorectal cancer undergoing endoscopic resection require additional surgery and regional lymph node dissection is inconclusive in current guidelines. However, we can be sure that in early colorectal cancer without lymph node metastasis, endoscopic resection alone does not affect the prognosis, and it greatly improves the quality of life and reduces the incidence of surgical complications while preserving organ integrity. Therefore, it is vital to discriminate patients without lymph node metastasis in T1 colorectal cancer, and this requires accurate predictors. This paper briefly explains the significance and shortcomings of traditional pathological factors, then extends and states the new pathological factors, clinical test factors, molecular biomarkers, and the risk assessment models of lymph node metastasis based on artificial intelligence.

Correlations of pathomorphological parameters between lesions at the invasive front and lymph node metastases in colorectal cancer: a retrospective clinical study

BACKGROUND

Lymph node (LN) metastasis is one of the most important indicators to evaluate stage, choose treatment strategy, and predict outcome of colorectal cancer (CRC). The morphological correlation between primary tumors and LN metastases can help predict the incidence of LN metastasis in CRC more accurately and assist with more individualized risk-stratification management decisions.

METHODS

A retrospective study was devised with paired tissue specimens from the invasive front of primary tumors and LN metastases in 426 patients after a radial surgery for CRC. According to the presence (N +) or absence (N-) of regional LN metastasis and the number of LN metastases (pN1a/1b/1c/2a/2b), comparisons were performed regarding tumor budding (TB) and poorly-differentiated clusters (PDC). In addition, their correlation with the incidence of LN metastasis and the extent were explored.

RESULTS

The TB and PDC in the invasive front of primary tumors presented significant correlations with the incidence of LN metastasis and the number of LN metastases in CRC (P < 0.001). TB2/3 led to a risk of LN metastasis 6.68-fold higher than TB1, while PDC2/3 resulted in a risk of LN metastasis 8.46-fold higher than PDC1. Additionally, the risk of developing 4 or more LN metastases was 3.08-fold and 2.86-fold higher upon TB2/3 and PDC2/3 than that with TB1 and PDC1, respectively. Moderate positive correlations were found between the invasive front of primary tumors and LN metastases in terms of TB and PDC, respectively.

CONCLUSIONS

TB and PDC, at the invasive tumor front are important morphological markers to evaluate LN metastasis in CRC, and they can be employed as reference indicators to assess or predict the potential of LN metastasis in CRC in clinical practice.

Oncologic outcomes of screen-detected and non-screen-detected T1 colorectal cancers

BACKGROUND

The incidence of T1 colorectal cancer (CRC) has increased with the implementation of CRC screening programs. It is unknown whether the outcomes and risk models for T1 CRC based on non-screen-detected patients can be extrapolated to screen-detected T1 CRC. This study aimed to compare the stage distribution and oncologic outcomes of T1 CRC patients within and outside the screening program.

METHODS

Data from T1 CRC patients diagnosed between 2014 and 2017 were collected from 12 hospitals in the Netherlands. The presence of lymph node metastasis (LNM) at diagnosis was compared between screen-detected and non-screen-detected patients using multivariable logistic regression. Cox proportional hazard regression was used to analyze differences in the time to recurrence (TTR), metastasis-free survival (MFS), cancer-specific survival (CSS), and overall survival. Additionally, the performance of conventional risk factors for LNM was evaluated across the groups.

RESULTS

1803 patients were included (1114 [62%] screen-detected), with median follow-up of 51 months (interquartile range 30). The proportion of LNM did not significantly differ between screen- and non-screen-detected patients (12.6% vs. 8.9%; odds ratio 1.41; 95%CI 0.89-2.23); a prediction model for LNM performed equally in both groups. The 3- and 5-year TTR, MFS, and CSS were similar for patients within and outside the screening program. However, overall survival was significantly longer in screen-detected T1 CRC patients (adjusted hazard ratio 0.51; 95%CI 0.38-0.68).

CONCLUSIONS

Screen-detected and non-screen-detected T1 CRCs have similar stage distributions and oncologic outcomes and can therefore be treated equally. However, screen-detected T1 CRC patients exhibit a lower rate of non-CRC-related mortality, resulting in longer overall survival.

Precision endoscopy in colorectal polyps' characterization and planning of endoscopic therapy

Precision endoscopy in the management of colorectal polyps and early colorectal cancer has emerged as the standard of care. It includes optical characterization of polyps and estimation of submucosal invasion depth of large nonpedunculated colorectal polyps to select the appropriate endoscopic resection modality. Over time, several imaging modalities have been implemented in endoscopic practice to improve optical performance. Among these, image-enhanced endoscopy systems and magnification endoscopy represent now well-established tools. New advanced technologies, such as endocytoscopy and confocal laser endomicroscopy, have recently shown promising results in predicting the histology of colorectal polyps. In recent years, artificial intelligence has continued to enhance endoscopic performance in the characterization of colorectal polyps, overcoming the limitations of other imaging modes. In this review we retrace the path of precision endoscopy, analyzing the yield of various endoscopic imaging techniques in personalizing management of colorectal polyps and early colorectal cancer.

Refining Risk Criteria May Substantially Reduce Unnecessary Additional Surgeries after Local Resection of T1 Colorectal Cancer

BACKGROUND

The low positive predictive value for lymph node metastases (LNM) of common practice risk criteria (CPRC) in T1 colorectal carcinoma (CRC) leads to manyunnecessary additional surgeries following local resection. This study aimed to identify criteria that may improve on the CPRC.

METHODS

Logistic regression analysis was performed to determine the association of diverse variables with LNM or 'poor outcome' (LNM and/or distant metastases and/or recurrence) in a single center T1 CRC cohort. The diagnostic capacity of the set of variables obtained was compared with that of the CPRC.

RESULTS

The study comprised 161 cases. Poorly differentiated clusters (PDC) and tumor budding grade > 1 (TB > 1) were the only independent variables associated with LNM. The area under the curve (AUC) for these criteria was 0.808 (CI 95% 0.717-0.880) compared to 0.582 (CI 95% 0.479-0.680) for CPRC. TB > 1 and lymphovascular invasion (LVI) were independently associated with 'poor outcome', with an AUC of 0.801 (CI 95% 0.731-0.859), while the AUC for CPRC was 0.691 (CI 95% 0.603-0.752). TB > 1, combined either with PDC or LVI, would reduce false positives between 41.5% and 45% without significantly increasing false negatives.

CONCLUSIONS

Indicating additional surgery in T1 CRC only when either TB > 1, PDC, or LVI are present could reduce unnecessary surgeries significantly.

Management after local excision of small rectal cancers. Indications for completion total mesorectal excision and possible alternatives

The treatment of superficial rectal cancers (local excision, or proctectomy with total mesorectal excision (TME) remains controversial. Endoscopy and endorectal ultrasonography are essential for the precise initial definition of these small cancers. During endoscopy, the depth of the lesion can be estimated using virtual chromoendoscopy with magnification, thereby aiding the assessment of the possibilities of local excision. Current international recommendations indicate completion proctectomy after wide local excision for cases where the pathologic examination reveals poorly-differentiated lesions, lymphovascular invasion, grade 2 or 3 tumor budding, and incomplete resection. But debate persists regarding whether the depth of submucosal invasion can accurately predict the risk of lymph node spread. Recent data from the literature suggest that the depth of submucosal invasion should no longer, by itself, be an indication for additional oncological surgery. Adjuvant radio-chemotherapy could be an alternative to completion proctectomy in patients with pT1 rectal cancer and unfavorable histopathological criteria. A Dutch randomized controlled trial is underway to validate this strategy.

Risk of recurrence in high-risk T1 colon cancer following endoscopic and surgical resection: registry-based cohort study

BACKGROUND

Endoscopic resection of T1 colon cancer (CC) is currently limited by guidelines related to risk of lymph node metastases. However, clinical outcome following endoscopic and surgical resection is poorly investigated.

METHOD

A retrospective multicentre national cohort study was conducted on prospectively collected data from the Swedish colorectal cancer registry on all non-pedunculated T1 CC patients undergoing surgical and endoscopic resection between 2009 and 2021. Patients were categorized on the basis of deep submucosal invasion (Sm2-3), lymphovascular invasion (LVI), poor tumour differentiation, and R1/Rx into low- and high-risk cases. The primary outcomes of interest were recurrence rates and disease-free interval (DFI, defined as time from treatment to date of recurrence) according to resection methods and risk factors (sex, age at diagnosis, histologic grade, LVI, perineural invasion, mucinous subtype, submucosal invasion, tumour location, resection margin and nodal positivity in the surgical group).

RESULTS

In total, 1805 patients undergoing endoscopic (488) and surgical (1317) resection with 60.0 months median follow-up were included. Recurrence occurred in 18 (3.7%) endoscopically and 48 (3.6%) surgically resected patients. Adjuvant treatment was administered in 7.4% and 0.2% of the cases respectively in the surgical and endoscopically treated patients. Five-year DFI was 95.6% after endoscopic and 96.2% after surgical resection, with no significant difference when adjusting for confounding factors (HR 1.03, 95% c.i. 0.56 to 1.91, P = 0.920). There were no statistically significant differences in recurrence comparing endoscopic (1.7%) versus surgical (3.6%) low-risk and endoscopic (5.4%) versus surgical (3.8%) high-risk cases. LVI was the only significant risk factor for recurrence in multivariate Cox regression (HR 3.73, 95% c.i. 1.76 to 7.92, P < 0.001).

CONCLUSIONS

This study shows no difference in recurrence after endoscopic and surgical resection in high-risk T1 CC. Although it was not possible to match groups according to treatment, the multivariate analysis showed that lymphovascular invasion was the only independent risk factor for recurrence.

Additional staining for lymphovascular invasion is associated with increased estimation of lymph node metastasis in patients with T1 colorectal cancer: Systematic review and meta-analysis

OBJECTIVES

Lymphovascular invasion (LVI) is a critical risk factor for lymph node metastasis (LNM), which requires additional surgery after endoscopic resection of T1 colorectal cancer (CRC). However, the impact of additional staining on estimating LNM is unclear. This systematic review aimed to evaluate the impact of additional staining on determining LNM in T1 CRC.

METHODS

We searched five electronic databases. Outcomes were diagnostic odds ratio (DOR), assessed using hierarchical summary receiver operating characteristic curves, and interobserver agreement among pathologists for positive LVI, assessed using Kappa coefficients (κ). We performed a subgroup analysis of studies that simultaneously included a multivariable analysis for other risk factors (deep submucosal invasion, poor differentiation, and tumor budding).

RESULTS

Among the 64 studies (18,097 patients) identified, hematoxylin-eosin (HE) and additional staining for LVI had pooled sensitivities of 0.45 (95% confidence interval [CI] 0.32-0.58) and 0.68 (95% CI 0.44-0.86), specificities of 0.88 (95% CI 0.78-0.94) and 0.76 (95% CI 0.62-0.86), and DORs of 6.26 (95% CI 3.73-10.53) and 6.47 (95% CI 3.40-12.32) for determining LNM, respectively. In multivariable analysis, the DOR of additional staining for LNM (DOR 5.95; 95% CI 2.87-12.33) was higher than that of HE staining (DOR 1.89; 95% CI 1.13-3.16) (P = 0.01). Pooled κ values were 0.37 (95% CI 0.22-0.52) and 0.62 (95% CI 0.04-0.99) for HE and additional staining for LVI, respectively.

CONCLUSION

Additional staining for LVI may increase the DOR for LNM and interobserver agreement for positive LVI among pathologists.

Association of survival with adjuvant chemotherapy in patients with stage IB gastric cancer: a multicentre, observational, cohort study

BACKGROUND

Recurrence following radical resection in patients with stage IB gastric cancer (GC) is not uncommon. However, whether postoperative adjuvant chemotherapy could reduce the risk of recurrence in stage IB GC remains contentious.

METHODS

We collected data on 2110 consecutive patients with pathologic stage IB (T1N1M0 or T2N0M0) GC who were admitted to 8 hospitals in China from 2009 to 2018. The survival of patients who received adjuvant chemotherapy was compared with that of postoperative observation patients using propensity score matching (PSM). Two survival prediction models were constructed to estimate the predicted net survival gain attributable to adjuvant chemotherapy.

FINDINGS

Of the 2110 patients, 1344 received adjuvant chemotherapy and 766 received postoperative observation. Following the 1-to-1 matching, PSM yielded 637 matched pairs. Among matched pairs, adjuvant chemotherapy was not associated with improved survival compared with postoperative observation (OS: hazard ratio [HR], 0.72; 95% CI, 0.52-1.00; DFS: HR, 0.91; 95% CI, 0.64-1.29). Interestingly, in the subgroup analysis, reduced mortality after adjuvant chemotherapy was observed in the subgroups with elevated serum CA19-9 (HR, 0.22; 95% CI, 0.08-0.57; P = 0.001 for multiplicative interaction), positive lymphovascular invasion (HR, 0.32; 95% CI, 0.17-0.62; P < 0.001 for multiplicative interaction), or positive lymph nodes (HR, 0.17; 95% CI, 0.07-0.38; P < 0.001 for multiplicative interaction). The survival prediction models mainly based on variables associated with chemotherapy benefits in the subgroup analysis demonstrated good calibration and discrimination, with relatively high C-indexes. The C-indexes for OS were 0.74 for patients treated with adjuvant chemotherapy and 0.70 for patients treated with postoperative observation. Two nomograms were built from the models that can calculate individualized estimates of expected net survival gain attributable to adjuvant chemotherapy.

INTERPRETATION

In this cohort study, pathologic stage IB alone was not associated with survival benefits from adjuvant chemotherapy compared with postoperative observation in patients with early-stage GC. High-risk clinicopathologic features should be considered simultaneously when evaluating patients with stage IB GC for adjuvant chemotherapy.

FUNDING

National Natural Science Foundation of China; the National Key R&D Program of China.

Risk assessment in pT1 colorectal cancer

Colorectal cancer (CRC) is a common malignancy worldwide and tumour stage is closely related to clinical outcome. A small but significant proportion of submucosal-invasive (ie, pT1) CRC are associated with regional lymph node metastases (LNM) and a worse prognosis. The likelihood of LNM in pT1 CRC needs to be balanced against the operative risk and costs of surgical resection when determining the best patient management. A wide range of histopathological and clinical factors may affect LNM risk in this setting. This script provides a comprehensive overview of the tumour and patient-associated features that have been linked to LNM risk in pT1 CRC. Some of the features are well established within the literature and are included in published guidelines, while others are novel and emerging in nature. Odds ratios for LNM that are associated with key predictive features are provided where appropriate, and published models developed as an aid to the calculation of LNM risk are discussed.

Prevalence and clinical significance of the muscle retracting sign during endoscopic submucosal dissection of large macronodular colorectal lesions (with videos)

BACKGROUND AND AIMS

The muscle retracting sign (MRS) can be present during endoscopic submucosal dissection (ESD) of macronodular colorectal lesions. The prevalence of MRS and its pathologic and clinical implications is unclear. This study evaluated the effect of MRS on the technical and clinical outcomes of ESD.

METHODS

All patients referred for ESD of protruding lesions or granular mixed lesions with >10 mm macronodule granular mixed laterally spreading tumors (LST-GMs) in 2 academic centers from January 2017 to October 2022 were prospectively included. Size of the macronodule was analyzed retrospectively. The primary outcome was the curative resection rate according to MRS status. Secondary outcomes were R0 resection, perforation, secondary surgery rate, and risk factors for MRS.

RESULTS

Of 694 lesions, 84 (12%) had MRS (MRS+). The curative resection rate was decreased by MRS (MRS+ 41.6% vs lesions without MRS [MRS-] 81.3%), whereas the perforation (MRS+ 22.6% vs MRS- 9.2%), submucosal cancer (MRS+ 34.9% vs MRS- 9.2%), and surgery (MRS+ 45.2% vs MRS- 6%) rates were increased. The R0 resection rate of MRS+ colonic lesions was lower than that of rectal lesions (53% vs 74.3%). In multivariate analysis, protruding lesions (odds ratio, 2.47; 95% confidence interval, 1.27-4.80) and macronodules >4 cm (odds ratio, 4.24; 95% confidence interval, 2.23-8.05) were risk factors for MRS.

CONCLUSIONS

MRS reduces oncologic outcomes and increases the perforation rate. Consequently, procedures in the colon should be stopped if MRS is detected, and those in the rectum should be continued due to the morbidity of alternative therapy.

Impact of surgery after endoscopically resected high-risk T1 colorectal cancer: results of an emulated target trial

BACKGROUND AND AIMS

We aimed to compare the long-term outcomes of patients with high-risk T1 colorectal cancer (CRC) resected endoscopically who received either additional surgery or surveillance.

METHODS

We used data from routine care to emulate a target trial aimed at comparing 2 strategies after endoscopic resection of high-risk T1 CRC: surgery with lymph node dissection (treatment group) versus surveillance alone (control group). All patients from 14 tertiary centers who underwent an endoscopic resection for high-risk T1 CRC between March 2012 and August 2019 were included. The primary outcome was a composite outcome of cancer recurrence or death at 48 months.

RESULTS

Of 197 patients included in the analysis, 107 were categorized in the treatment group and 90 were categorized in the control group. From baseline to 48 months, 4 of 107 patients (3.7%) died in the treatment group and 6 of 90 patients (6.7%) died in the control group. Four of 107 patients (3.7%) in the treatment group experienced a cancer recurrence and 4 of 90 patients (4.4%) in the control group experienced a cancer recurrence. After balancing the baseline covariates by inverse probability of treatment weighting, we found no significant difference in the rate of death and cancer recurrence between patients in the 2 groups (weighted hazard ratio, .95; 95% confidence interval, .52-1.75).

CONCLUSIONS

Our study suggests that patients with high-risk T1 CRC initially treated with endoscopic resection may not benefit from additional surgery.

Long-term outcomes of endoscopic or surgical resection in T1 colorectal cancer patients: a retrospective cohort study

BACKGROUND

The personalized treatments of T1 colorectal cancer (CRC) remains controversial. We compared the long-term outcomes of T1 CRC patients after endoscopic resection (ER) and surgery, and evaluated the risk factors for the long-term prognosis.

METHODS

T1 CRCs after resection at the Cancer Hospital, Chines Academy of Medical Sciences from June 2011 to November 2021 were reviewed. High-risk factors included positive resection margin, poor differentiation, deep submucosal invasion (DSI ≥ 1000 μm), lymphovascular invasion and intermediate/high tumor budding. Comparative analyses were conducted based on three treatment methods: follow-up after ER (Group A), additional surgery after ER (Group B) and initial surgery (Group C). The primary endpoints included recurrence-free survival (RFS) and overall survival (OS). Cox proportional hazard regression models were constructed to identify risk factors for RFS and OS.

RESULTS

A total of 528 patients were enrolled (173 patients in Group A, 102 patients in Group B, 253 patients in Group C). The 3-year RFS, 5-year RFS, 3-year OS, and 5-year OS rates were 96.7%, 94.7%, 99.1%, and 97.8%, respectively. In the absence of other high-risk factors, RFS (P = 0.321) and OS (P = 0.155) of patients with DSI after ER were not inferior to those after surgery. Multivariate analyses identified sex (HR 0.379; 95% CI 0.160-0.894), Charlson comorbidities index (CCI) (HR 3.330; 95% CI 1.571-7.062), margin (HR 8.212; 95% CI 2.325-29.006), and budding (HR 3.794; 95% CI 1.686-8.541) as independent predictive factors of RFS, and identified CCI (HR 10.266; 95% CI 2.856-36.899) as an independent predictive factor of OS.

CONCLUSION

The long-term outcomes of ER are comparable to those of surgery in T1 CRC patients with DSI when other high-risk factors are negative. Resection margin, tumor budding, sex, and CCI may be the most important long-term prognostic factors for T1 CRC patients.

Diagnostic Accuracy of Highest-Grade or Predominant Histological Differentiation of T1 Colorectal Cancer in Predicting Lymph Node Metastasis: A Systematic Review and Meta-Analysis

INTRODUCTION

Treatment guidelines for colorectal cancer (CRC) suggest 2 classifications for histological differentiation-highest grade and predominant. However, the optimal predictor of lymph node metastasis (LNM) in T1 CRC remains unknown. This systematic review aimed to evaluate the impact of the use of highest-grade or predominant differentiation on LNM determination in T1 CRC.

METHODS

The study protocol is registered in the International Prospective Register of Systematic Reviews (PROSPERO, registration number: CRD42023416971) and was published in OSF ( https://osf.io/TMAUN/ ) on April 13, 2023. We searched 5 electronic databases for studies assessing the diagnostic accuracy of highest-grade or predominant differentiation to determine LNM in T1 CRC. The outcomes were sensitivity and specificity. We simulated 100 cases with T1 CRC, with an LNM incidence of 11.2%, to calculate the differences in false positives and negatives between the highest-grade and predominant differentiations using a bootstrap method.

RESULTS

In 42 studies involving 41,290 patients, the differentiation classification had a pooled sensitivity of 0.18 (95% confidence interval [CI] 0.13-0.24) and 0.06 (95% CI 0.04-0.09) ( P < 0.0001) and specificity of 0.95 (95% CI 0.93-0.96) and 0.98 (95% CI 0.97-0.99) ( P < 0.0001) for the highest-grade and predominant differentiations, respectively. In the simulation, the differences in false positives and negatives between the highest-grade and predominant differentiations were 3.0% (range 1.6-4.4) and -1.3% (range -2.0 to -0.7), respectively.

DISCUSSION

Highest-grade differentiation may reduce the risk of misclassifying cases with LNM as negative, whereas predominant differentiation may prevent unnecessary surgeries. Further studies should examine differentiation classification using other predictive factors.

Development and validation of comprehensive nomograms from the SEER database for predicting early mortality in metastatic rectal cancer patients

BACKGROUND

Metastatic rectal cancer is an incurable malignancy, which is prone to early mortality. We aimed to establish nomograms for predicting the risk of early mortality in patients with metastatic rectal cancer.

METHODS

In this study, clinical data were obtained from the Surveillance, Epidemiology, and End Results (SEER) database.We utilized X-tile software to determine the optimal cut-off points of age and tumor size in diagnosis. Significant independent risk factors for all-cause and cancer-specific early mortality were determined by the univariate and multivariate logistic regression analyses, then we construct two practical nomograms. In order to assess the predictive performance of nomograms, we performed calibration plots, time-dependent receiver-operating characteristic curve (ROC), decision curve analysis (DCA) and clinical impact curve (CIC).

RESULTS

A total of 2570 metastatic rectal cancer patients were included in the study. Multivariate logistic regression analyses revealed that age at diagnosis, CEA level, tumor size, surgical intervention, chemotherapy, radiotherapy, and metastases to bone, brain, liver, and lung were independently associated with early mortality of metastatic rectal cancer patients in the training cohort. The area under the curve (AUC) values of nomograms for all-cause and cancer-specific early mortality were all higher than 0.700. Calibration curves indicated that the nomograms accurately predicted early mortality and exhibited excellent discrimination. DCA and CIC showed moderately positive net benefits.

CONCLUSIONS

This study successfully generated applicable nomograms that predicted the high-risk early mortality of metastatic rectal cancer patients, which can assist clinicians in tailoring more effective treatment regimens.

Management of non-curative endoscopic resection of T1 colon cancer

Endoscopic resection techniques enable en-bloc resection of T1 colon cancers. A complete removal of T1 colon cancer can be considered curative when histologic examination of the specimens shows none of the high-risk factors for lymph nodes metastases. Criteria predicting lymph nodes metastases include deep submucosal invasion, poor differentiation, lymphovascular invasion, and high-grade tumor budding. In these cases, complete (R0), local endoscopic resection is considered sufficient as negligible risk of lymph nodes metastases does not outweigh morbidity and mortality associated with surgical resection. Challenges arise when endoscopic resection is incomplete (RX/R1) or high-risk histological features are present. The risk of lymph node metastasis in T1 CRC ranges from 1% to 36.4%, depending on histologic risk factors. Presence of any risk factor labels the patient "high risk," warranting oncologic surgery with mesocolic lymphadenectomy. However, even if 70%-80% of T1-CRC patients are classified as high-risk, more than 90% are without lymph node involvement after oncological surgery. Surgical overtreatment in T1 CRC is a challenge, requiring a balance between oncologic safety and minimizing morbidity/mortality. This narrative review explores the landscape of managing non-curative T1 colon cancer, focusing on the choice between advanced endoscopic resection techniques and surgical interventions. We discuss surveillance strategies and shared decision-making, emphasizing the importance of a multidisciplinary approach.

Endoscopic intermuscular dissection for locally advanced rectal cancer: A case report

BACKGROUND

Endoscopic submucosal dissection is considered curative for patients with early rectal cancer when level of submucosal invasion is < 1000 microns with favourable histopathological features. Recent data suggests even deeper submucosal invasion can potentially be curative if R0 resection can be achieved and when no high-risk histopathological features are seen in the resected specimen. To achieve R0 resection, deeper dissection is required.

CASE SUMMARY

A 66 year old New Zealand European male presented with 3 mo history of per rectal bleeding. He was referred for a colonoscopy test to investigate this further. This revealed a malignant appearing lesion in the rectum. Biopsies however showed high grade dysplasia only. Given endoscopic appearances suspicious for deep submucosal invasion, patient was consented for endoscopic intermuscular dissection (EID). The case was successfully performed, and the presence of muscularis propria was confirmed in the resected specimen. There were no complications and total procedure time was 124 min. Lesion was clear of radial margins however deep margins were positive confirming it was at least a pT2 cancer. Patient was recommended to have further treatment but could not have radical surgery due to comorbidities and instead was referred for long course chemoradiotherapy.

CONCLUSION

EID is a safe and feasible option for management of rectal cancer in highly selected patients.

A Retrospective Multicenter Study of Risk Factors, Stratification, and Prognosis of Lymph Node Metastasis in T1 and T2 Colorectal Cancer

BACKGROUND

The objective of this study was to compare the long-term prognosis of patients with T1 and T2 colorectal cancer (CRC) according to lymph node metastasis (LNM) and to identify risk factors for LNM.

METHODS

We retrospectively reviewed patients who underwent curative resection for T1 or T2 CRC at five University-affiliated hospitals between January 2012 and December 2021. The patients were divided into several groups depending on the presence of LNM or the number of risk factors.

RESULTS

Of the total 765 patients, 87 (11.3%) patients had LNM. These patients had poorer recurrence-free survival (RFS) than patients without LNM (72.6% vs. 88.6%). The multivariable analysis showed that high-grade tumors (p = 0.003), lymphovascular invasion (p < 0.001), and rectal location (p = 0.049) were independent predictors of LNM. When divided into groups according to the number of the three risk factors, the risk of LNM increased from 5.4% (ultralow-risk group; no risk factor) to 60.0% (high-risk group; all three risk factors) and the 5-year RFS rate decreased from 96.3% in the ultralow-risk group to 60% in the high-risk group (p < 0.001).

CONCLUSION

Radical surgery should be considered for T1 and T2 CRC patients with these risk factors.

Lymph Node Molecular Analysis with OSNA Enables the Identification of pT1 CRC Patients at Risk of Recurrence: A Multicentre Study

Early-stage colorectal carcinoma (CRC)-pT1-is a therapeutic challenge and presents some histological features related to lymph node metastasis (LNM). A significant proportion of pT1 CRCs are treated surgically, resulting in a non-negligible surgical-associated mortality rate of 1.5-2%. Among these cases, approximately 6-16% exhibit LNM, but the impact on survival is unclear. Therefore, there is an unmet need to establish an objective and reliable lymph node (LN) staging method to optimise the therapeutic management of pT1 CRC patients and to avoid overtreating or undertreating them. In this multicentre study, 89 patients with pT1 CRC were included. All histological features associated with LNM were evaluated. LNs were assessed using two methods, One-Step Nucleic Acid Amplification (OSNA) and the conventional FFPE plus haematoxylin and eosin (H&E) staining. OSNA is an RT-PCR-based method for amplifying CK19 mRNA. Our aim was to assess the performance of OSNA and H&E in evaluating LNs to identify patients at risk of recurrence and to optimise their clinical management. We observed an 80.9% concordance in LN assessment using the two methods. In 9% of cases, LNs were found to be positive using H&E, and in 24.7% of cases, LNs were found to be positive using OSNA. The OSNA results are provided as the total tumour load (TTL), defined as the total tumour burden present in all the LNs of a surgical specimen. In CRC, a TTL ≥ 6000 CK19 m-RNA copies/µL is associated with poor prognosis. Three patients had TTL > 6000 copies/μL, which was associated with higher tumour budding. The discrepancies observed between the OSNA and H&E results were mostly attributed to tumour allocation bias. We concluded that LN assessment with OSNA enables the identification of pT1 CRC patients at some risk of recurrence and helps to optimise their clinical management.

Combined endoscopic and laparoscopic surgery (CELS) for early colon cancer in high-risk patients

BACKGROUND

Local excision of early colon cancers could be an option in selected patients with high risk of complications and no sign of lymph node metastasis (LNM). The primary aim was to assess feasibility in high-risk patients with early colon cancer treated with Combined Endoscopic and Laparoscopic Surgery (CELS).

METHODS

A non-randomized prospective feasibility study including 25 patients with Performance Status score ≥ 1 and/or American Society of Anesthesiologists score ≥ 3, and clinical Union of International Cancer Control stage-1 colon cancer suitable for CELS resection. The primary outcome was failure of CELS resection, defined as either: Incomplete resection (R1/R2), local recurrence within 3 months, complication related to CELS within 30 days (Clavien-Dindo grade ≥ 3), death within 30 days or death within 90 days due to complications to surgery.

RESULTS

Fifteen patients with clinical T1 (cT1) and ten with clinical T2 (cT2) colon cancer and without suspicion of metastases were included. Failure occurred in two patients due to incomplete resections. Histopathological examination classified seven patients as having pT1, nine as pT2, six as pT3 adenocarcinomas, and three as non-invasive tumors. In three patients, the surgical strategy was changed intraoperatively to conventional colectomy due to tumor location or size. Median length of stay was 1 day. Seven patients had completion colectomy performed due to histological high-risk factors. None had LNM.

CONCLUSIONS

In selected patients, CELS resection was feasible, and could spare some patients large bowel resection.

pT1 colorectal cancer: A treatment dilemma

The implementation of population screening programs for colorectal cancer (CRC) has led to a considerable increase in the prevalence pT1-CRC originating on polyps amenable by local treatments. However, a high proportion of patients are referred for unnecessary oncological surgeries without a clear benefit in terms of survival. Selecting the appropriate endoscopic resection technique in the moment of diagnosis becomes crucial to provide the best treatment alternative to each individual polyp and patient. For this, it is imperative to increase the optical diagnostic skill for differentiating pT1-CRCs and decide the appropriate initial therapy. En bloc resection is crucial to obtain an adequate histological specimen that might allow organ preserving therapeutic management. In this review, we address key challenges in T1 CRC management, explore the efficacy and safety of the available diagnostic and therapeutic approaches, and shed light on upcoming advances in the field.

Impact of adjuvant chemotherapy on long-term overall survival in patients with high-risk stage II colon cancer: a nationwide cohort study

BACKGROUND

This study aimed to investigate the impact of adjuvant chemotherapy on long-term survival in unselected patients with high-risk stage II colon cancer including an analysis of each high-risk feature.

MATERIALS AND METHODS

Data from the Danish Colorectal Cancer Group, the National Patient Registry and the Danish Pathology Registry from 2014 to 2018 were merged. Patients surviving > 90 days were included. High-risk features were defined as emergency presentation, including self-expanding metal stents (SEMS)/loop-ostomy as a bridge to resection, grade B or C anastomotic leakage, pT4 tumors, lymph node yield < 12 or signet cell carcinoma. Eligibility criteria for chemotherapy were age < 75 years, proficient MMR gene expression, and performance status ≤ 2. The primary outcome was 5-year overall survival. Secondary outcomes included the proportion of eligible patients allocated for adjuvant chemotherapy and the time to first administration.

RESULTS

In total 939 of 3937 patients with stage II colon cancer had high-risk features, of whom 408 were eligible for chemotherapy. 201 (49.3%) patients received adjuvant chemotherapy, with a median time to first administration of 35 days after surgery. The crude 5-year overall survival was 84.9% in patients receiving adjuvant chemotherapy compared with 66.3% in patients not receiving chemotherapy, p < 0.001. This association corresponded to an absolute risk difference of 14%.

CONCLUSION

5-year overall survival was significantly higher in patients with high-risk stage II colon cancer treated with adjuvant chemotherapy compared with no chemotherapy. Adjuvant treatment was given to less than half of the patients who were eligible for it.

Endoscopic Treatment of T1 Colorectal Cancer

Commonly accepted criteria for curative resection of T1 colorectal cancer include R0 resection with horizontal and vertical clear margins (R0), absence of lympho-vascular or vessel infiltration (L0, V0), a low to moderate histological grading (G1/2), low tumor cell budding, and limited (<1000 µm) infiltration into the submucosa. However, submucosal infiltration depth in the absence of other high-risk features has recently been questioned as a high-risk situation for lymph-node metastasis. Consequently, endoscopic resection techniques should focus on the acquisition of qualitatively and quantitively sufficient submucosal tissue. Here, we summarize the current literature on lymph-node metastasis risk after endoscopic resection of T1 colorectal cancer. Moreover, we discuss different endoscopic resection techniques with respect to the quality of the resected specimen.

Dilemmas in the Clinical Management of pT1 Colorectal Cancer

Implementation of population-based colorectal cancer screening programs has led to increases in the incidence of pT1 colorectal cancer. These incipient invasive cancers have a very good prognosis and can be treated locally, but more than half of these cases are treated with surgery due to the presence of histological high-risk criteria. These high-risk criteria are suboptimal, with no consensus among clinical guidelines, heterogeneity in definitions and assessment, and poor concordance in evaluation, and recent evidence suggests that some of these criteria considered high risk might not necessarily affect individual prognosis. Current criteria classify most patients as high risk with an indication for additional surgery, but only 2-10.5% have lymph node metastasis, and the residual tumor is present in less than 20%, leading to overtreatment. Patients with pT1 colorectal cancer have excellent disease-free survival, and recent evidence indicates that the type of treatment, whether endoscopic or surgical, does not significantly impact prognosis. As a result, the protective role of surgery is questionable. Moreover, surgery is a more aggressive treatment option, with the potential for higher morbidity and mortality rates. This article presents a comprehensive review of recent evidence on the clinical management of pT1 colorectal cancer. The review analyzes the limitations of histological evaluation, the prognostic implications of histological risk status and the treatment performed, the adverse effects associated with both endoscopic and surgical treatments, and new advances in endoscopic treatment.

Nomogram as a novel predictive tool for lymph node metastasis in T1 colorectal cancer treated with endoscopic resection: a nationwide, multicenter study

BACKGROUND AND AIMS

Since 2009, the Japanese Society for Cancer of the Colon and Rectum guidelines have recommended that tumor budding and submucosal invasion depth, in addition to lymphovascular invasion and tumor grade, be included as risk factors for lymph node metastasis (LNM) in patients with T1 colorectal cancer (CRC). In this study, a novel nomogram was developed and validated by usirge-scale, real-world data, including the Japanese Society for Cancer of the Colon and Rectum risk factors, to accurately evaluate the risk of LNM in T1 CRC.

METHODS

Data from 4673 patients with T1 CRC treated at 27 high-volume institutions between 2009 and 2016 were analyzed for LNM risk. To prepare a nonrandom split sample, the total cohort was divided into development and validation cohorts. Pathologic findings were extracted from the medical records of each participating institution. The discrimination ability was measured by using the concordance index, and the variability in each prediction was evaluated by using calibration curves.

RESULTS

Six independent risk factors for LNM, including submucosal invasion depth and tumor budding, were identified in the development cohort and entered into a nomogram. The concordance index was .784 for the clinical calculator in the development cohort and .790 in the validation cohort. The calibration curve approached the 45-degree diagonal in the validation cohort.

CONCLUSIONS

This is the first nomogram to include submucosal invasion depth and tumor budding for use in routine pathologic diagnosis based on data from a nationwide multi-institutional study. This nomogram, developed with real-world data, should improve decision-making for an appropriate treatment strategy for T1 CRC.

"Transanal endoscopic microsurgery" with a flexible colonoscope (F-TEM): a new endoscopic treatment for suspicious deep submucosal invasion T1 rectal carcinoma

BACKGROUND

Endoscopic techniques allow resections of deep submucosal invasion rectal carcinoma, but mostly are facing issues such as costs, follow-up care or size limit. Our aim was to design a new endoscopic technique, which retains the advantages over surgical resections while eliminating the disadvantages mentioned above.

PATIENTS AND METHODS

We propose a technique for the resection of the superficial rectal tumours, with highly suspicious deep submucosal invasion. It combines steps of endoscopic submucosal dissection, muscular resection and edge-to-edge suture of the muscular layers, finally performing the equivalent of a "transanal endoscopic microsurgery" with a flexible colonoscope (F-TEM).

RESULTS

A 60-year-old patient was referred to our unit, following the discovery of a 15 mm distal rectum adenocarcinoma. The computed tomography and the endoscopic ultrasound examination revealed a T1 tumour, without secondary lesions. Considering that the initial endoscopic evaluation highlighted a depressed central part of the lesion, with several avascular zones, an F-TEM was performed, without severe complication. The histopathological examination revealed negative resection margins, without risk factors for lymph node metastasis, no adjuvant therapy being proposed.

CONCLUSION

F-TEM allows endoscopic resection of highly suspicious deep submucosal invasion T1 rectal carcinoma and it proves to be a feasible alternative to surgical resection or other endoscopic treatments as endoscopic submucosal dissection or intermuscular dissection.

Diagnostic endoscopic submucosal dissection for colorectal lesions with suspected deep invasion

BACKGROUND

 Endoscopic submucosal dissection (ESD) is potentially a curative treatment for T1 colorectal cancer under certain conditions. The aim of this study was to evaluate the feasibility and effectiveness of ESD for lesions with a suspicion of focal deep invasion.

METHODS

 In this retrospective multicenter study, consecutive patients with colorectal neoplasia displaying a focal (< 15 mm) deep invasive pattern (FDIP) that were treated by ESD were included. We excluded ulcerated lesions (Paris III), lesions with distant metastasis, and clearly advanced tumors (tumoral strictures).

RESULTS

 124 patients benefited from 126 diagnostic dissection attempts for FDIP lesions. Dissection was feasible in 120/126 attempts (95.2 %) and, where possible, the en bloc and R0 resection rates were 95.8 % (115/120) and 76.7 % (92/120), respectively. Thirty-three resections (26.2 %) were for very low risk tumors, so considered curative, and 38 (30.2 %) were for low risk lesions. Noncurative R0 resections were for lesions with lymphatic or vascular invasion (LVI; n = 8), or significant budding (n = 9), and LVI + budding combination (n = 4).

CONCLUSION

 ESD is feasible and safe for colorectal lesions with an FDIP ≤ 15 mm. It was curative in 26.6 % of patients and could be a valid option for a further 30.6 % of patients with low risk T1 cancers, especially for frail patients with co-morbidities.

Biparametric magnetic resonance imaging-based radiomics features for prediction of lymphovascular invasion in rectal cancer

BACKGROUND

Preoperative assessment of lymphovascular invasion(LVI) of rectal cancer has very important clinical significance. However, accurate preoperative imaging evaluation of LVI is highly challenging because the resolution of MRI is still limited. Relatively few studies have focused on prediction of LVI of rectal cancer with the tool of radiomics, especially in patients with negative statue of MRI-based extramural vascular invasion (mrEMVI).The purpose of this study was to explore the preoperative predictive value of biparametric MRI-based radiomics features for LVI of rectal cancer in patients with the negative statue of mrEMVI.

METHODS

The data of 146 cases of rectal adenocarcinoma confirmed by postoperative pathology were retrospectively collected. In the cases, 38 had positive status of LVI. All patients were examined by MRI before the operation. The biparametric MRI protocols included T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI). We used whole-volume three-dimensional method and two feature selection methods, minimum redundancy maximum relevance (mRMR) and least absolute shrinkage and selection operator (LASSO), to extract and select the features. Logistics regression was used to construct models. The area under the receiver operating characteristic curve (AUC) and DeLong's test were used to evaluate the diagnostic performance of the radiomics based on T2WI and DWI and the combined models.

RESULTS

Radiomics models based on T2WI and DWI had good predictive performance for LVI of rectal cancer in both the training cohort and the validation cohort. The AUCs of the T2WI model were 0.87 and 0.87, and the AUCs of the DWI model were 0.94 and 0.92. The combined model was better than the T2WI model, with AUCs of 0.97 and 0.95. The predictive performance of the DWI model was comparable to that of the combined model.

CONCLUSIONS

The radiomics model based on biparametric MRI, especially DWI, had good predictive value for LVI of rectal cancer. This model has the potential to facilitate the clinical recognition of LVI in rectal cancer preoperatively.

Prognostic Factors for Lymph Node Metastases in pT1 Colorectal Cancer Differ According to Tumor Morphology: A Nationwide Cohort Study

OBJECTIVE

To investigate whether there is a differential impact of histopathological risk factors for lymph node metastases (LNM) in pedunculated and nonpedunculated pT1 colorectal cancers (CRC).

BACKGROUND

Tumor budding, lymphovascular invasion (LVI), and venous invasion (VI) are recognized risk factors for LNM in pT1 CRC. Whether the importance of these factors varies according to tumor morphology is unknown.

METHODS

Patients undergoing resection with lymphadenectomy for pT1 CRC in Denmark from January 2016 to January 2019 were identified in the Danish Colorectal Cancer Database and clinicopathological data was reviewed. Prognostic factors for LNM were investigated using multivariable analyses on the cohort as a whole as well as when stratifying according to tumor morphology (pedunculated vs. nonpedunculated).

RESULTS

A total of 1167 eligible patients were identified, of whom 170 had LNM (14.6%). Independent prognostic factors for LNM included LVI [odds ratio (OR)=4.26, P <0.001], VI (OR=3.42, P <0.001), tumor budding (OR=2.12, P =0.002), high tumor grade (OR=2.76, P =0.020), and age per additional year (OR=0.96, P <0.001). On subgroup analyses, LVI and VI remained independently prognostic for LNM regardless of tumor morphology. However, tumor budding was only prognostic for LNM in pedunculated tumors (OR=4.19, P <0.001), whereas age was only prognostic in nonpedunculated tumors (OR=0.61, P =0.003).

CONCLUSIONS

While LVI and LI were found to be prognostic of LNM in all pT1 CRC, the prognostic value of tumor budding differs between pedunculated and nonpedunculated tumors. Thus, tumor morphology should be taken into account when considering completion surgery in patients undergoing local excision.

Risk of recurrence after endoscopic resection of nonpedunculated T1 colorectal cancer

BACKGROUND

The long-term outcome after local excision of T1 colorectal cancer (CRC) remains unknown. The aim of this study was to examine clinical and histopathological risk factors for recurrence in patients with T1 CRC undergoing endoscopic resection.

METHODS

This was a retrospective registry-based population study on prospectively collected data of all patients with nonpedunculated T1 CRC undergoing only local excision (no salvage surgery) in Sweden between 2009 and 2018. Potential risk factors for recurrence, including age, sex, tumor location, resection margins, lymphovascular, perineural, and submucosal invasion, grade of differentiation, and mucinous subtype, were analyzed using univariate and multivariate cox regression.

RESULTS

Median follow-up time was 60 months, and 28 /602 patients (4.7 %) had a recurrence (13 local and 18 distant). Recurrence rate stratified by submucosal invasion was: Sm1 3.5 % (14 /397), Sm2 6.0 % (8 /133), and Sm3 8.3 % (6 /72), with no significant differences. Resection margins, lymphovascular and perineural invasion, grade of differentiation, mucinous subtype, and age were not significant risk factors for recurrence. In contrast, rectal location was found to be a significant risk factor for tumor recurrence in multivariate analysis (hazard ratio 3.08, P = 0.006). The 3- and 5-year disease-free survival was 96.2 % and 91.1 %, respectively, in T1 CRC patients undergoing endoscopic resection.

CONCLUSION

Tumor recurrence was rare (4.7 %) in this large population-based study on recurrence after local excision of nonpedunculated T1 CRC. Rectal location was an independent risk factor for recurrence, suggesting the need for strict surveillance after endoscopic resection of early rectal cancer.

Relevance of polyp size for primary endoscopic full-thickness resection of suspected T1 colorectal cancers

BACKGROUND

En bloc local excision of suspected T1 colorectal cancer (CRC) provides optimal tumor risk assessment with curative intent. Endoscopic full-thickness resection (eFTR) with an over-the-scope device has emerged as a local excision technique for T1 CRCs, but data on the upper size limit for achieving a histological complete (R0) resection are lacking. We aimed to determine the influence of polyp size on the R0 rate.

METHODS

eFTR procedures for suspected T1 CRCs performed between 2015 and 2021 were selected from the endoscopy databases of three tertiary centers. The main outcome was R0 resection, defined as tumor- and dysplasia-free margins (≥ 0.1 mm) for both the deep and lateral resection margins. Regression analysis was performed to identify risk factors for R1/Rx resection, mainly focusing on endoscopically estimated polyp size.

RESULTS

136 patients underwent eFTR for suspected T1 CRC (median size 15 mm [IQR 13-18 mm]; 83.1 % cancer). The rates of technical success and R0 resection were 87.5 % (119/136; 95 %CI 80.9 %-92.1 %) and 79.7 % (106/136; 95 %CI 72.1 %-85.7 %), respectively. Increasing polyp size was significantly associated with R1/Rx resection (risk ratio 2.35 per 5-mm increase, 95 %CI 1.80-3.07; P < 0.001). The R0 rate was 89.9 % (80/89) for polyps ≤ 15 mm, 71.4 % (25/35) for 16-20 mm, and 11.1 % (1/9) for those > 20 mm.

CONCLUSIONS

eFTR is associated with a 90 % R0 rate for T1 CRCs of ≤ 15 mm. Performing eFTR for polyps 16-20 mm should depend on access, their mobility, and the availability of alternative resection techniques. eFTR for > 20-mm polyps results in a high R1 rate and should not be recommended.

Endoscopic intermuscular dissection for deep submucosal invasive cancer in the rectum: a new endoscopic approach

BACKGROUND

The risk of lymph node metastasis associated with deep submucosal invasion should be balanced against the mortality and morbidity of total mesorectal excision (TME). Dissection through the submucosa hinders radical deep resection, and full-thickness resection may influence the outcome of completion TME. Endoscopic intermuscular dissection (EID) in between the circular and longitudinal part of the muscularis propria could potentially provide an R0 resection while leaving the rectal wall intact.

METHODS

In this prospective cohort study, the data of patients treated with EID for suspected deep submucosal invasive rectal cancer between 2018 and 2020 were analyzed. Study outcomes were the percentages of technical success, R0 resection, curative resection, and adverse events.

RESULTS

67 patients (median age 67 years; 73 % men) were included. The median lesion size was 25 mm (interquartile range 20-33 mm). The rates of overall technical success, R0 resection, and curative resection were 96 % (95 %CI 89 %-99 %), 81 % (95 %CI 70 %-89 %), and 45 % (95 %CI 33 %-57 %). Only minor adverse events occurred in eight patients (12 %).

CONCLUSION

EID for deep invasive T1 rectal cancer appears to be feasible and safe, and the high R0 resection rate creates the potential of rectal preserving therapy in 45 % of patients.

Clinical outcome of non-curative endoscopic submucosal dissection for early colorectal cancer

OBJECTIVE

Endoscopic submucosal dissection (ESD) in a curative intent for submucosa-invasive early (T1) colorectal cancers (T1-CRCs) often leads to subsequent surgical resection in case of histologic parameters indicating higher risk of nodal involvement. In some cases, however, the expected benefit may be offset by the surgical risks, suggesting a more conservative approach.

DESIGN

Retrospective analysis of consecutive patients with T1-CRC who underwent ESD at 13 centres ending inclusion in 2019 (n=3373). Cases with high risk of nodal involvement (non-curative ESD: G3, submucosal invasion>1000 µm, lymphovascular involvement, budding or incomplete resection/R1) were analysed if follow-up data (endoscopy/imaging) were available, regardless of the postendoscopic management (follow-up vs surgery) selected by the multidisciplinary teams in these institutions. Comorbidities were classified according to Charlson Comorbidity Index (CCI). Outcomes were disease recurrence, death and disease-related death rates in the two groups. Rate of residual disease (RD) at both the previous resection site and regional lymph nodes was assessed in the surgical cases as well as from follow-up in the follow-up group.

RESULTS

Of 604 patients treated by colorectal ESD for submucosally invasive cancer, 207 non-curative resections (34.3%) were included (138 male; mean age 67.6±10.9 years); in 65.2% of cases, no complete resection was achieved (R1). Of the 207 cases, 60.9% (n=126; median CCI: 3; IQR: 2-4) underwent surgical treatment with RD in 19.8% (25/126), while 39.1% (n=81, median CCI: 5; IQR: 4-6) were followed up by endoscopy in all cases. Patients in the follow-up group had a higher overall mortality (HR=3.95) due to non-CRC causes (n=9, mean survival after ESD 23.7±13.7 months). During this follow-up time, tumour recurrence and disease-specific survival rates were not different between the groups (median follow-up 30 months; range: 6-105).

CONCLUSION

Following ESD for a lesion at high risk of RD, follow-up only may be a reasonable choice in patients at high risk for surgery. Also, endoscopic resection quality should be improved.

TRIAL REGISTRATION NUMBER

NCT03987828.

Composite scoring system and optimal tumor budding cut-off number for estimating lymph node metastasis in submucosal colorectal cancer

BACKGROUND

Tumor budding is associated with lymph node (LN) metastasis in submucosal colorectal cancer (CRC). However, the rate of LN metastasis associated with the number of tumor buds is unknown. Here, we determined the optimal tumor budding cut-off number and developed a composite scoring system (CSS) for estimating LN metastasis of submucosal CRC.

METHODS

In total, 395 patients with histologically confirmed T1N0-2M0 CRC were evaluated. The clinicopathological characteristics were subjected to univariate and multivariate analyses. The Akaike information criterion (AIC) values of the multivariate models were evaluated to identify the optimal cut-off number. A CSS for LN metastasis was developed using independent risk factors.

RESULTS

The prevalence of LN metastasis was 13.2%. Histological differentiation, lymphatic or venous invasion, and tumor budding were associated with LN metastasis in univariate analyses. In multivariate models adjusted for histological differentiation and lymphatic or venous invasion, the AIC value was lowest for five tumor buds. Unfavorable differentiation (odds ratio [OR], 8.16; 95% confidence interval [CI], 1.80-36.89), lymphatic or venous invasion (OR, 5.91; 95% CI, 2.91-11.97), and five or more tumor buds (OR, 3.01; 95% CI, 1.21-7.69) were independent risk factors. In a CSS using these three risk factors, the rates of LN metastasis were 5.6%, 15.5%, 31.0%, and 52.4% for total composite scores of 0, 1, 2, and ≥ 3, respectively.

CONCLUSIONS

For the estimation of LN metastasis in submucosal CRC, the optimal tumor budding cut-off number was five. Our CSS can be utilized to estimate LN metastasis.

Deep Submucosal Invasion Is Not an Independent Risk Factor for Lymph Node Metastasis in T1 Colorectal Cancer: A Meta-Analysis

BACKGROUND & AIMS

Deep submucosal invasion (DSI) is considered a key risk factor for lymph node metastasis (LNM) and important criterion to recommend surgery in T1 colorectal cancer. However, metastatic risk for DSI is shown to be low in the absence of other histologic risk factors. This meta-analysis determines the independent risk of DSI for LNM.

METHODS

Suitable studies were included to establish LNM risk for DSI in univariable analysis. To assess DSI as independent risk factor, studies were eligible if risk factors (eg, DSI, poor differentiation, lymphovascular invasion, and high-grade tumor budding) were simultaneously included in multivariable analysis or LNM rate of DSI was described in absence of poor differentiation, lymphovascular invasion, and high-grade tumor budding. Odds ratios (OR) and 95% CIs were calculated.

RESULTS

Sixty-seven studies (21,238 patients) were included. Overall LNM rate was 11.2% and significantly higher for DSI-positive cancers (OR, 2.58; 95% CI, 2.10-3.18). Eight studies (3621 patients) were included in multivariable meta-analysis and did not weigh DSI as a significant predictor for LNM (OR, 1.73; 95% CI, 0.96-3.12). As opposed to a significant association between LNM and poor differentiation (OR, 2.14; 95% CI, 1.39-3.28), high-grade tumor budding (OR, 2.83; 95% CI, 2.06-3.88), and lymphovascular invasion (OR, 3.16; 95% CI, 1.88-5.33). Eight studies (1146 patients) analyzed DSI as solitary risk factor; absolute risk of LNM was 2.6% and pooled incidence rate was 2.83 (95% CI, 1.66-4.78).

CONCLUSIONS

DSI is not a strong independent predictor for LNM and should be reconsidered as a sole indicator for oncologic surgery. The expanding armamentarium for local excision as first-line treatment prompts serious consideration in amenable cases to tailor T1 colorectal cancer management.