Management of T1 colorectal cancers after endoscopic treatment based on the risk stratification of lymph node metastasis

Clinical usefulness of hybrid endoscopic submucosal dissection for T1b colorectal carcinomas ≤20 mm to ensure adequate vertical margins

Objective

To evaluate endoscopic resection strategies for cT1b colorectal carcinomas (CRCs) ≤20 mm to determine strategies that enable adequate vertical margins (VMs).

Methods

We enrolled 128 consecutive patients with cT1b colorectal carcinomas ≤20 mm resected by endoscopic mucosal resection or hybrid endoscopic submucosal dissection (ESD). Tumor lifting conditions after submucosal injection were classified into type A (lifting, soft dome-like), type B (lifting, hard trapezoid-like), and non-lifting (positive non-lifting sign). Predictors of positive VMs (VM 1) and adequate VMs were identified.

Results

All non-lifting tumors were resected by hybrid ESD and VMs were ≥500 µm. Vertical margin 1 tumors were only found in the endoscopic mucosal resection group, in which, the proportion of type B tumors with VM 1 was significantly higher than that of tumors with negative VMs (p < 0.01). Type A tumors showed no significant between-group differences. Among type B tumors, the proportion of VMs ≥500 µm was significantly higher (p < 0.01) and the VM distance was significantly longer (p < 0.01) in the hybrid ESD group than in the endoscopic mucosal resection group.

Conclusions

Hybrid ESD can be selected for type B tumors to ensure adequate VMs.

A Novel 4-Tier Classification for Tumor Budding and the Importance of Tumor Invasive Patterns in the Prognosis of Colorectal Cancer

BACKGROUND

Colorectal carcinoma (CRC) is a major global health issue, with significant morbidity and mortality. Although the TNM staging system remains the standard for prognosticating CRC, it fails to capture the full complexity of tumor behavior. Tumor budding (TB) and tumor invasive patterns (TIPs) are emerging as promising histopathological markers that may provide additional prognostic insights, particularly in predicting the nodal metastasis (N), lymphovascular invasion (LVI), and perineural invasion (PNI). This study aims to assess the correlation between TB, TIP, and CRC prognosis.

MATERIALS AND METHODS

This ambidirectional observational study, conducted at our tertiary care center, included 60 biopsy-proven CRC patients, the majority of whom were at stages 2 and 3. Histopathological evaluation of TB and TIP were performed on Hematoxylin and Eosin (H&E) stained slides. TB and TIP categories are then compared against various histopathological parameters. Statistical analysis was performed.

RESULTS

In the 60 CRC cases studied, low TB was observed in 60% of cases, whereas high TB was seen in 5%. TIP analysis showed that 57% of cases had expansile patterns and 35% of cases had infiltrative patterns. A significant association was found between TB and N (p - 0.018) as well as TIP and PNI (p - 0.016). Multivariate analysis revealed that TB remained a strong predictor for N (OR (odds ratio) = 12.8 and p < 0.001). Although not statistically significant, distinct trends were observed between low and zero TB. Our study's findings on TB and TIP align with several historical studies, reinforcing their prognostic significance in CRC. Despite being a small cohort, our study aligns with these findings, emphasizing TB and TIP as critical prognostic markers in CRC.

CONCLUSION

TB and TIP are valuable prognostic tools in CRC, offering insights into tumor behavior and metastasis potential. Their incorporation into routine histopathological evaluation could enhance prognostic accuracy.

Is endoscopic submucosal dissection safe in the management of early-stage colorectal cancers?

BACKGROUND

Endoscopic submucosal dissection (ESD) is increasingly being adopted for the treatment of early-stage colorectal cancer (CRC) lesions.

METHODS

We retrospectively analyzed patients with early-stage CRC treated between 2015 and 2023, using ESD and colectomy databases, categorizing them into three groups: ESD only (n ​= ​24), oncological colorectal resection (OCR) only (n ​= ​90), and OCR after ESD (n ​= ​59). We compared pathological and oncological outcomes among these groups.

RESULTS

The OCR after ESD group demonstrated higher non-granular lesions, and deeper submucosal invasion compared to ESD only group. The primary OCR group showed higher 2-year overall survival compared to ESD-only group (98.9 ​% vs 85.6 ​%, p ​= ​0.01), with no colorectal cancer-related mortality in any of the groups. Notably, 2-year disease-free survival rates were comparable across all groups (93.8 ​% ESD only, 88.0 ​% primary OCR only, and 97.8 ​% for OCR after ESD, p ​= ​0.27).

CONCLUSION

The current study highlights feasibility the promising potential and oncologic safety of ESD in carefully selected patients with early malignant lesions.

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.

Pitfalls during histological assessment in locally resected pT1 colorectal cancer

Colorectal cancer (CRC) is a common malignancy worldwide, and the stage of the tumour is closely related to clinical outcome. Bowel cancer screening programmes have resulted in the identification of colorectal cancer at earlier stages. Approximately 10% of patients with the earliest stage of CRC (i.e. pT1) will possess regional lymph node metastases (LNM). Therefore, if these patients have initially been treated by local resection (e.g. polypectomy), this subgroup will require surgical resection. Identification of pathological risk factors for LNM within locally resected pT1 CRC is a very important process during the histological assessment of these lesions. This paper describes the most commonly encountered and clinically significant difficulties in the histological assessment of these cases. These pitfalls are illustrated using four examples of locally resected pT1 CRC that were received by our department during routine diagnostic practice.

Comparison of the prognosis and lymph node metastasis between no tumor budding and low-grade tumor budding in T1 and T2 colorectal cancer

Tumor budding is a significant prognostic factor in colorectal cancer (CRC) management and is graded as follows: 0-4 buds as low, 5-9 buds as intermediate, and > 10 buds as high. However, the specific prognostic difference between cases with 0 buds (BD0) and those with 1-4 buds (BD1) is not well established owing to a lack of comparative studies. This study aimed to examine and compare the rate of lymph node (LN) metastasis and prognosis by distinguishing between BD0 and BD1 within the low-grade category (0-4 buds) of tumor budding in submucosa (T1) and muscularis propria (T2) CRC. We retrospectively identified 223 cases of T1 and T2 CRC underwent surgery from 2015 to 2018 across three medical institutions using medical records. Pathology, including assessing tumor budding, was subsequently reconfirmed, and the recurrence and survival of patients were evaluated up to December 2023. Patients in the BD1 group exhibited a higher T stage than those in the BD0 group, accompanied by significantly increased rates of lymphovascular and perineural invasion. The prevalence of LN metastasis was 14.8%. No significant differences in LN metastasis were observed between the BD0 and BD1 groups. In a multivariate analysis exploring factors associated with LN metastasis, relevant factors included lymphatic invasion, perineural invasion, and ≥ 5 buds. There were no significant differences in 5-year survival and progression free survival rates between the BD0 and BD1 groups (P = 0.971). This study confirmed that there was no significant difference in LN metastasis or prognosis between patients with BD0 and BD1.

Efficacy of a whole slide image-based prediction model for lymph node metastasis in T1 colorectal cancer: A systematic review

BACKGROUND AND AIM

Accurate stratification of the risk of lymph node metastasis (LNM) following endoscopic resection of submucosal invasive (T1) colorectal cancer (CRC) is imperative for determining the necessity for additional surgery. In this systematic review, we evaluated the efficacy of prediction of LNM by artificial intelligence (AI) models utilizing whole slide image (WSI) in patients with T1 CRC.

METHODS

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a systematic review was conducted through searches in PubMed (MEDLINE), Embase, and the Cochrane Library for relevant studies published up to December 2023. The inclusion criteria were studies assessing the accuracy of hematoxylin and eosin-stained WSI-based AI models for predicting LNM in patients with T1 CRC.

RESULTS

Four studies met the criteria for inclusion in this systematic review. The area under the receiver operating characteristic curve for these AI models ranged from 0.57 to 0.76. In the three studies in which AI performance was compared directly with current treatment guidelines, AI consistently exhibited a higher area under the receiver operating characteristic curve. At a fixed sensitivity of 100%, specificities ranged from 18.4% to 45.0%.

CONCLUSIONS

Artificial intelligence models based on WSI can potentially address the issue of diagnostic variability between pathologists and exceed the predictive accuracy of current guidelines. However, these findings require confirmation by larger studies that incorporate external validation.

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.

Approaches and considerations in the endoscopic treatment of T1 colorectal cancer

The detection of early colorectal cancer (CRC) is increasing through the implementation of screening programs. This increased detection enhances the likelihood of minimally invasive surgery and significantly lowers the risk of recurrence, thereby improving patient survival and reducing mortality rates. T1 CRC, the earliest stage, is treated endoscopically in cases with a low risk of lymph node metastasis (LNM). The advantages of endoscopic treatment compared with surgery include minimal invasiveness and limited tissue disruption, which reduce morbidity and mortality, preserve bowel function to avoid colectomy, accelerate recovery, and improve cost-effectiveness. However, T1 CRC has a risk of LNM. Thus, selection of the appropriate treatment between endoscopic treatment and surgery, while avoiding overtreatment, is challenging considering the potential for complete resection, LNM, and recurrence risk.

Role of the artificial intelligence in the management of T1 colorectal cancer

Approximately 10% of submucosal invasive (T1) colorectal cancers demonstrate extraintestinal lymph node metastasis, necessitating surgical intervention with lymph node dissection. The ability to identify T1b (submucosal invasion depth ≥ 1000 µm) as a risk factor for lymph node metastasis via pre-treatment endoscopy is crucial in guiding treatment strategies. Accurately distinguishing T1b from T1a (submucosal invasion depth < 1000 µm) or dysplasia remains a significant challenge for artificial intelligence (AI) systems, which require high and consistent diagnostic capabilities. Moreover, as endoscopic therapies like endoscopic full-thickness resection and endoscopic intermuscular dissection evolve, and the focus on reducing unnecessary surgeries intensifies, the initial management of T1 colorectal cancers via endoscopic treatment is anticipated to increase. Consequently, the development of highly accurate and reliable AI systems is essential, not only for pre-treatment depth assessment but also for post-treatment risk stratification of lymph node metastasis. While such AI diagnostic systems are still under development, significant advancements are expected in the near future to improve decision-making in T1 colorectal cancer management.

Early Rectal Cancer and Local Excision: A Narrative Review

A rise in the incidence of early rectal cancer consequent to bowel-screening programs around the world and an increase in the incidence in young adults has led to a growing interest in organ-sparing treatment options. The rectum, being the most distal portion of the large intestine, is a fertile ground for local excision techniques performed with endoscopic or surgical techniques. Moreover, the advancement in endoscopic optical evaluation and the better definition of imaging techniques allow for a more precise local staging of early rectal cancer. Although the local treatment of early rectal cancer seems promising, in clinical practice, a significant number of patients who could benefit from local excision techniques undergo total mesorectal excision (TME) as the first approach. All relevant prospective clinical trials were identified through a computer-assisted search of the PubMed, EMBASE, and Medline databases until January 2024. This review is dedicated to endoscopic and surgical local excision in the treatment of early rectal cancer and highlights its possible role in current and future clinical practice, taking into account surgical completion techniques and chemoradiotherapy.

Differentiation grade as a risk factor for lymph node metastasis in T1 colorectal cancer

OBJECTIVES

Japanese guidelines include high-grade (poorly differentiated) tumors as a risk factor for lymph node metastasis (LNM) in T1 colorectal cancer (CRC). However, whether the grading is based on the least or most predominant component when the lesion consists of two or more levels of differentiation varies among institutions. This study aimed to investigate which method is optimal for assessing the risk of LNM in T1 CRC.

METHODS

We retrospectively evaluated 971 consecutive patients with T1 CRC who underwent initial or additional surgical resection from 2001 to 2021 at our institution. Tumor grading was divided into low-grade (well- to moderately differentiated) and high-grade based on the least or predominant differentiation analyses. We investigated the correlations between LNM and these two grading analyses.

RESULTS

LNM was present in 9.8% of patients. High-grade tumors, as determined by least differentiation analysis, accounted for 17.0%, compared to 0.8% identified by predominant differentiation analysis. A significant association with LNM was noted for the least differentiation method (p < 0.05), while no such association was found for predominant differentiation (p = 0.18). In multivariate logistic regression, grading based on least differentiation was an independent predictor of LNM (p = 0.04, odds ratio 1.68, 95% confidence interval 1.00-2.83). Sensitivity and specificity for detecting LNM were 27.4% and 84.1% for least differentiation, and 2.1% and 99.3% for predominant differentiation, respectively.

CONCLUSIONS

Tumor grading via least differentiation analysis proved to be a more reliable measure for assessing LNM risk in T1 CRC compared to grading by predominant differentiation.

Colon cancer: the 2023 Korean clinical practice guidelines for diagnosis and treatment

Colorectal cancer is the third most common cancer in Korea and the third leading cause of death from cancer. Treatment outcomes for colon cancer are steadily improving due to national health screening programs with advances in diagnostic methods, surgical techniques, and therapeutic agents.. The Korea Colon Cancer Multidisciplinary (KCCM) Committee intends to provide professionals who treat colon cancer with the most up-to-date, evidence-based practice guidelines to improve outcomes and help them make decisions that reflect their patients' values and preferences. These guidelines have been established by consensus reached by the KCCM Guideline Committee based on a systematic literature review and evidence synthesis and by considering the national health insurance system in real clinical practice settings. Each recommendation is presented with a recommendation strength and level of evidence based on the consensus of the committee.

Diagnostic performance of endocytoscopy with normal pit-like structure sign for colorectal low-grade adenoma compared with conventional modalities

Objectives

A "resect-and-discard" strategy has been proposed for diminutive adenomas in the colorectum. However, this strategy is sometimes difficult to implement because of the lack of confidence in differentiating low-grade adenoma (LGA) from advanced lesions such as high-grade adenoma or carcinoma. To perform real-time precise diagnosis of LGA with high confidence, we assessed whether endocytoscopy (EC) diagnosis, considering normal pit-like structure (NP-sign), an excellent indicator of LGA, could have additional diagnostic potential compared with conventional modalities.

Methods

All the neoplastic lesions that were observed by non-magnifying narrow-band imaging (NBI), magnifying NBI (M-NBI), magnifying pit pattern, and EC prior to pathological examination between 2005 and 2018 were retrospectively investigated. The neoplastic lesions were classified into two categories: LGA and other neoplastic lesions. We assessed the differential diagnostic ability of EC with NP-sign between LGA and other neoplastic lesions compared with that of NBI, M-NBI, pit pattern, and conventional EC in terms of sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve (AUC).

Results

A total of 1376 lesions from 1097 patients were eligible. The specificity (94.9%), accuracy (91.5%), and area under the receiver operating characteristic curve (0.95) of EC with NP-sign were significantly higher than those of NBI, M-NBI, pit pattern, and conventional EC.

Conclusions

EC diagnosis with NP-sign has significantly higher diagnostic performance for predicting colorectal LGA compared with the conventional modalities and enables stratification of neoplastic lesions for "resect-and-discard" with higher confidence.

Curative criteria for endoscopic treatment of colorectal cancer

As endoscopic treatment enables en bloc resection of T1 colorectal cancers, the risk of recurrence, often assimilated to the risk of lymph node metastases, must be assessed in order to offer patients an additional treatment if this risk is deemed significant. The curative criteria currently used by most guidelines are depth of invasion <1 mm, well or moderately differentiated tumour, absence of lympho-vascular invasion, absence of significant budding and tumour-free resection margins. However, these factors must be assessed by qualified pathologists, as they are difficult to evaluate. Moreover, the combination of these factors leads to unnecessary surgery in over 80 % of patients whose tumours are classified as high risk. Refinement of current criteria and research into new tumour and immunological markers are needed to better predict the actual risk of our patients.

Use of artificial intelligence in the management of T1 colorectal cancer: a new tool in the arsenal or is deep learning out of its depth?

The field of artificial intelligence is rapidly evolving, and there has been an interest in its use to predict the risk of lymph node metastasis in T1 colorectal cancer. Accurately predicting lymph node invasion may result in fewer patients undergoing unnecessary surgeries; conversely, inadequate assessments will result in suboptimal oncological outcomes. This narrative review aims to summarize the current literature on deep learning for predicting the probability of lymph node metastasis in T1 colorectal cancer, highlighting areas of potential application and barriers that may limit its generalizability and clinical utility.

Lymph Node Metastases and Associated Recurrence-Free Survival in Microsatellite Stable and Unstable Colon Cancer

BACKGROUND

In contrast to microsatellite stable (MSS) colon cancer, predictors of lymph node metastases and their association with recurrence are not well-defined in microsatellite instability (MSI) colon cancer.

METHODS

A cohort of nonmetastatic colon cancer patients undergoing surgery between 2015 and 2021 were evaluated for predictors of lymph node metastases (LNMs) and their association with recurrence-free survival (RFS).

RESULTS

Of 1466 patients included in the analyses, 361 (25 %) had MSI. Compared with MSS, MSI was associated with earlier stage, fewer LNMs in the patients with N1 or N2 disease, and fewer high-risk features. Compared with the T3-T4 MSS patients, the odds ratios for LNM were 0.52 (95% confidence interval [CI], 0.38-0.71) for the T3-T4 MSI patients, 0.27 (95% CI, 0.38-0.71) for the T1-T2 MSS patients, and 0.15 (95 % CI, 0.08-0.26) for the T1-T2 MSI patients. In both groups, LNMs were associated with T category, patient age, and venous, lymphatic, or perineural invasion. In the MSS patients, LNMs were additionally associated with patient sex and histologic grade. Compared with the MSS patients, the MSI patients with N0 and N1 disease had a better 3-year RFS. However, the MSI patients with N2 disease had a lower rate of 3-year RFS than the MSS patients (hazard ratio, 19.75 vs 4.49).

CONCLUSIONS

In MSI colon cancer, LNMs are 50 % less prevalent, but the factors associated with LNM are like those in MSS colon cancer. The improved prognosis traditionally associated with early-stage MSI colon cancers dissipates with four or more LNMs. These findings should be taken into consideration by clinicians selecting the most appropriate course of treatment for MSI colon cancer.

Whole slide image-based prediction of lymph node metastasis in T1 colorectal cancer using unsupervised artificial intelligence

OBJECTIVES

Lymph node metastasis (LNM) prediction for T1 colorectal cancer (CRC) is critical for determining the need for surgery after endoscopic resection because LNM occurs in 10%. We aimed to develop a novel artificial intelligence (AI) system using whole slide images (WSIs) to predict LNM.

METHODS

We conducted a retrospective single center study. To train and test the AI model, we included LNM status-confirmed T1 and T2 CRC between April 2001 and October 2021. These lesions were divided into two cohorts: training (T1 and T2) and testing (T1). WSIs were cropped into small patches and clustered by unsupervised K-means. The percentage of patches belonging to each cluster was calculated from each WSI. Each cluster's percentage, sex, and tumor location were extracted and learned using the random forest algorithm. We calculated the areas under the receiver operating characteristic curves (AUCs) to identify the LNM and the rate of over-surgery of the AI model and the guidelines.

RESULTS

The training cohort contained 217 T1 and 268 T2 CRCs, while 100 T1 cases (LNM-positivity 15%) were the test cohort. The AUC of the AI system for the test cohort was 0.74 (95% confidence interval [CI] 0.58-0.86), and 0.52 (95% CI 0.50-0.55) using the guidelines criteria (P = 0.0028). This AI model could reduce the 21% of over-surgery compared to the guidelines.

CONCLUSION

We developed a pathologist-independent predictive model for LNM in T1 CRC using WSI for determination of the need for surgery after endoscopic resection.

TRIAL REGISTRATION

UMIN Clinical Trials Registry (UMIN000046992, https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000053590).

An artificial intelligence prediction model outperforms conventional guidelines in predicting lymph node metastasis of T1 colorectal cancer

Background

According to guidelines, a lot of patients with T1 colorectal cancers (CRCs) undergo additional surgery with lymph node dissection after being treated by endoscopic resection (ER) despite the low incidence of lymph node metastasis (LNM).

Aim

The aim of this study was to develop an artificial intelligence (AI) model to more effectively identify T1 CRCs at risk for LNM and reduce the rate of unnecessary additional surgery.

Methods

We retrospectively analyzed 651 patients with T1 CRCs. The patient cohort was randomly divided into a training set (546 patients) and a test set (105 patients) (ratio 5:1), and a classification and regression tree (CART) algorithm was trained on the training set to develop a predictive AI model for LNM. The model used 12 clinicopathological factors to predict positivity or negativity for LNM. To compare the performance of the AI model with the conventional guidelines, the test set was evaluated according to the Japanese Society for Cancer of the Colon and Rectum (JSCCR) and National Comprehensive Cancer Network (NCCN) guidelines. Finally, we tested the performance of the AI model using the test set and compared it with the JSCCR and NCCN guidelines.

Results

The AI model had better predictive performance (AUC=0.960) than the JSCCR (AUC=0.588) and NCCN guidelines (AUC=0.850). The specificity (85.8% vs. 17.5%, p<0.001), balanced accuracy (92.9% vs. 58.7%, p=0.001), and the positive predictive value (36.3% vs. 9.0%, p=0.001) of the AI model were significantly better than those of the JSCCR guidelines and reduced the percentage of the high-risk group for LNM from 83.8% (JSCCR) to 20.9%. The specificity of the AI model was higher than that of the NCCN guidelines (85.8% vs. 82.4%, p=0.557), but there was no significant difference between the two. The sensitivity of the NCCN guidelines was lower than that of our AI model (87.5% vs. 100%, p=0.301), and according to the NCCN guidelines, 1.2% of the 105 test set patients had missed diagnoses.

Conclusion

The AI model has better performance than conventional guidelines for predicting LNM in T1 CRCs and therefore could significantly reduce unnecessary additional surgery.

CT morphological features for predicting the risk of lymph node metastasis in T1 colorectal cancer

OBJECTIVES

The aim of this study is to evaluate the feasibility of clinicopathological characteristics and computed tomography (CT) morphological features in predicting lymph node metastasis (LNM) for patients with T1 colorectal cancer (CRC).

METHODS

A total of 144 patients with T1 CRC who underwent CT scans and surgical resection were retrospectively included in our study. The clinicopathological characteristics and CT morphological features were assessed by two observers. Univariate and multiple logistic regression analyses were used to identify significant LNM predictive variables. Then a model was developed using the independent predictive factors. The predictive model was subjected to bootstrapping validation (1000 bootstrap resamples) to calculate the calibration curve and relative C-index.

RESULTS

LNM were found in 30/144 patients (20.83%). Four independent risk factors were determined in the multiple logistic regression analysis, including presence of necrosis (adjusted odds ratio [OR] = 10.32, 95% confidence interval [CI] 1.96-54.3, p = 0.004), irregular outer border (adjusted OR = 5.94, 95% CI 1.39-25.45, p = 0.035), and heterogeneity enhancement (adjusted OR = 7.35, 95% CI 3.11-17.38, p = 0.007), as well as tumor location (adjusted ORright-sided colon = 0.05 [0.01-0.60], p = 0.018; adjusted ORrectum = 0.22 [0.06-0.83], p = 0.026). In the internal validation cohort, the model showed good calibration and good discrimination with a C-index of 0.89.

CONCLUSIONS

There are significant associations between lymphatic metastasis status and tumor location as well as CT morphologic features in T1 CRC, which could help the doctor make decisions for additional surgery after endoscopic resection.

KEY POINTS

• LNM more frequently occurs in left-sided T1 colon cancer than in right-sided T1 colon and rectal cancer. • CT morphologic features are risk factors for LNM of T1 CRC, which may be related to fundamental biological behaviors. • The combination of tumor location and CT morphologic features can more effectively assist in predicting LNM in patients with T1 CRC, and decrease the rate of unnecessary extra surgeries after endoscopic resection.

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.

Serum amyloid A1 recruits neutrophils to the invasive front of T1 colorectal cancers

BACKGROUND AND AIM

The tumor microenvironment plays an essential role in the development and progression of colorectal cancer (CRC). We recently reported that crosstalk between CRC cells and tumor-associated macrophages (TAMs) via serum amyloid A1 (SAA1) promotes invasion by T1 CRCs. In the present study, we aimed to clarify the role of neutrophils in early CRCs.

METHODS

Immunohistochemical analysis of CD66b, chemokine CXC motif ligand 8 (CXCL8 or interleukin-8, IL-8) and matrix metalloproteinase-9 (MMP-9) was performed using primary T1 CRCs (n = 49). The HL-60 human promyelocytic leukemia cell line and THP-1 human monocytic leukemia cell line were used to obtain neutrophil-like and macrophage-like cells, respectively. Boyden chamber assays were used to analyze cell migration and invasion, and quantitative RT-PCR was used to analyze gene expression.

RESULTS

Immunohistochemical analysis revealed accumulation of neutrophils at the SAA1-positive invasive front of T1 CRCs. Experiments using HL-60 cells suggested that treatment with SAA1 induced neutrophil migration and expression of CXCL8 and MMP-9 in neutrophils and that neutrophils promote CRC cell migration and invasion. Immunohistochemistry confirmed accumulation of CXCL8- or MMP-9-positive neutrophils at the SAA1-positive invasive front of T1 CRCs. Moreover, co-culture experiments using CRC, THP-1 and HL-60 cells suggested that CRC cells activated by macrophages upregulate CXCL8 and MMP-9 in neutrophils.

CONCLUSIONS

Our results suggest that interplay between macrophages and CRC cells leads to recruitment of neutrophils to the invasive front of T1 CRCs and that SAA1 secreted by CRC cells activate neutrophils to promote invasion.

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.

Long-term Outcomes After Endoscopic Submucosal Dissection for Large Colorectal Epithelial Neoplasms: A Prospective, Multicenter, Cohort Trial From Japan

BACKGROUND & AIMS

To determine the long-term outcomes after colorectal endoscopic submucosal dissection (ESD), we conducted a large, multicenter, prospective cohort trial with a 5-year observation period.

METHODS

Between February 2013 and January 2015, we consecutively enrolled 1740 patients with 1814 colorectal epithelial neoplasms ≥20 mm who underwent ESD. Patients with noncurative resection (non-CR) lesions underwent additional radical surgery, as needed. After the initial treatment, intensive 5-year follow-up with planned multiple colonoscopies was conducted to identify metastatic and/or local recurrences. Primary outcomes were overall survival, disease-specific survival, and intestinal preservation rates. The rates of local recurrence and metachronous invasive cancer were evaluated as the secondary outcomes.

RESULTS

The 5-year overall survival, disease-specific survival, and intestinal preservation rates were 93.6%, 99.6%, and 88.6%, respectively. Patients with CR lesions had no metastatic occurrence, and patients with non-CR lesions had 4 metastatic occurrences. Kaplan-Meier curves revealed that overall survival and disease-specific survival rates were significantly higher in patients with CR lesions than in those with non-CR lesions (P > .001 and P = .009, respectively). Local recurrence occurred in only 8 lesions (0.5%), which were successfully resected by subsequent endoscopic treatment. Multiple logistic regression analyses revealed that piecemeal resection (hazard ratio, 8.19; 95% CI, 1.47-45.7; P = .02) and margin-positive resection (hazard ratio, 8.06; 95% CI, 1.76-37.0; P = .007) were significant independent predictors of local recurrence after colorectal ESD. Fifteen metachronous invasive cancers (1.0%) were identified during surveillance colonoscopy, most of which required surgical resection.

CONCLUSIONS

A favorable long-term prognosis indicates that ESD can be the standard treatment for large colorectal epithelial neoplasms.

CLINICAL TRIAL REGISTRATION NUMBER

UMIN000010136.

New scoring system to distinguish deep invasive submucosal and muscularis propria colorectal cancer during colonoscopy: a development and global multicenter external validation study (e-T2 Score)

BACKGROUND AND AIMS

Diagnostics to differentiate deep submucosal invasive (invasion depth ≥1000 μm [T1b]) colorectal cancer (CRC) from muscularis propria invasive (T2) CRC are limited. We aimed to establish and validate a scoring system that differentiates T1b from T2.

METHODS

A multicenter retrospective cross-validation study was performed. Four hundred sixty-one consecutive pathologically confirmed T1b or T2 CRCs were divided into the development (T1b, 222; T2, 189) and internal validation (T1b, 31; T2, 19) cohorts. Eight potential endoscopic findings were evaluated using the development cohort: loss of lobulation, deep depression, demarcated depressed area, protuberance within the depression, expanding appearance, fold convergency, erosion or white plaque, and Borrmann type 2 or 3 tumor. A scoring system that differentiates T1b from T2 was developed, and diagnostic performance was tested using the internal validation cohort by 8 endoscopists. External validation was conducted using 50 CRC images by 4 endoscopists from other institutions, including outside of Japan.

RESULTS

Multivariate analysis identified the following 5 independent predictive endoscopic findings of T2 CRC: deep depression (odds ratio [OR], 2.08; 95% confidence interval [CI], 1.07-4.04), demarcated depressed area (OR, 4.40; 95% CI, 1.39-13.9), 4-fold convergency or more (OR, 3.41; 95% CI, 1.90-6.11), erosion or white plaque (OR, 8.28; 95% CI, 2.77-24.7), and Borrmann type 2 or 3 tumor (OR, 8.76; 95% CI, 3.58-21.5). The area under the receiver-operating characteristic curve (AUROC) was .90 (95% CI, .87-.93) in the development cohort, .80 (95% CI, .76-.85) in the internal validation, and .76 (95% CI, .69-.83) in the external validation.

CONCLUSIONS

We established and validated a new scoring system to differentiate T1b from T2 CRC using 5 simple endoscopic findings.

Risk Factors for Predicting Lymph Node Metastasis in Submucosal Colorectal Cancer

Objectives:

The cornerstone of treating colorectal cancer (CRC) is generally a surgical resection with lymph node (LN) dissection. The tools for predicting lymph node metastasis (LNM) in submucosal (SM) CRC are useful to avoid unnecessary surgical resection.

Methods:

Retrospectively, we analyzed 526 consecutive patients with SM CRC who underwent surgical resection at the Osaka International Cancer Institute, Osaka University Hospital, and Minoh City Hospital, Japan, between 1984 and 2012. The Osaka International Cancer Institute group and the Osaka University Hospital group were randomly divided into a training set and a test set of 2:1. The prediction model was validated in Minoh City Hospital.

Results:

We partitioned patients using three risk factors involved in the presence or absence of LNM in SM CRC: lymphatic invasion (Ly), budding grade (BD) and the depth of submucosal invasion (DSI) (cut-off value 2789 μm) that were significantly different in the multivariate analysis. As a result, a predictive model of “LNM <5%” when “Ly negative and DSI <2789 μm” was evaluated. We similarly partitioned by DSI 3000 μm as easy-to-evaluate values in clinical use. We developed the additional model for predicting LNM is 1.05%, that is, LNM <5%, when there are “Ly negative and DSI <3000 μm.”

Conclusions:

As a limitation, only patients who underwent surgical resection were included in this study. This predictive model could help clinicians and CRC patients decide on the additional surgery required after endoscopic resection.

Current problems and perspectives of pathological risk factors for lymph node metastasis in T1 colorectal cancer: Systematic review

With the prevalence of endoscopic submucosal dissection and endoscopic full thickness resection, which enable complete resection of T1 colorectal cancer with a negative margin, the treatment strategy following endoscopic resection has become more important. The necessity of secondary surgical resection is determined on the basis of the risk of lymph node metastasis according to the histopathological findings of resected specimens because ~10% of T1 colorectal cancer cases have lymph node metastasis. The current Japanese treatment guidelines state four risk factors for lymph node metastasis: lymphovascular invasion, histological differentiation, depth of submucosal invasion, and tumor budding. These guidelines have succeeded in stratifying the low-risk group for lymph node metastasis, in which endoscopic resection alone is acceptable for cure. On the other hand, there are some problems: there is variation in diagnosis methods and low interobserver agreement for each pathological factor and 90% of surgical resections are unnecessary, with lymph node metastasis negativity. To ensure patients with T1 colorectal cancer receive more appropriate treatment, these problems should be addressed. In this systematic review, we gave some suggestions to these practical issues of four pathological factors as predictors.

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.

A model based on endorectal ultrasonography predicts lateral lymph node metastasis in low and middle rectal cancer

PURPOSE

To investigate the risk factors for lymph node (LN) metastasis in low and middle rectal tumors, construct a predictive model and test the model's diagnostic efficacy.

METHODS

The clinical and pathological data of 172 patients with rectal cancer confirmed by surgery were retrospectively evaluated, among whom 61 patients were finally included in this study. Patients were divided into positive groups and negative groups based on LN metastasis, and risk factors that might affect LN metastasis were analyzed. Finally, a risk predictive model was constructed based on the weights of each risk factor.

RESULTS

Compared with pathology, the efficacy of diagnosing LN metastasis only according to conventional endorectal ultrasonography (ERUS) features of LN was not high, with sensitivity 67%, specificity 86%, positive predictive value 76%, negative predictive value 80%, and accuracy 79%. Univariate analysis showed that circumferential angle of the tumor, ultrasonic T- stage (UT stage), conventional ultrasound features diagnosis of LN metastasis, strain ratio (SR) of tumor were risk factors for LN metastasis, while vascular resistance index of rectal tumor was protective factor. Multivariate analysis showed that UT stage (OR = 7.188, p = 0.049), conventional ultrasound features diagnosis of LN metastasis (OR = 8.010, p = 0.025) and SR (OR = 5.022, p = 0.031) were independent risk factors for LN metastasis. These risk factors were included in logistic regression analysis and the model was established, Y = -7.3 + 1.9 X10 + 2.1 X11 + 1.6 X13 (Y = Logit[P], P: LN metastasis rate, X10: UT stage, X11: conventional ultrasound features diagnosis of LN metastasis, X13: SR). The receiver operating characteristic (ROC) curve was used to test the model's predictive efficacy, the area under the curve was 0.95, sensitivity: 95%, specificity: 87%. Hosmer-Lemeshow goodness of fit test showed X2 = 6.015, p = 0.65 (p > 0.05), indicating that the model had a high predictive value.

CONCLUSION

Evaluation of perirectal LN metastasis only based on conventional ERUS features of LN was not effective enough. UT stage of tumor, conventional ultrasound features diagnosis of LN metastasis and SR were independent risk factors for LN metastasis. The predictive model had good assessment efficacy and had certain clinical application value.

Establishment of a Dynamic Nomogram for Predicting the Risk of Lymph Node Metastasis in T1 Stage Colorectal Cancer

BACKGROUND

Accurate prediction of the risk of lymph node metastasis in patients with stage T1 colorectal cancer is crucial for the formulation of treatment plans for additional surgery and lymph node dissection after endoscopic resection. The purpose of this study was to establish a predictive model for evaluating the risk of LNM in patients with stage T1 colorectal cancer.

METHODS

The clinicopathological and imaging data of 179 patients with T1 stage colorectal cancer who underwent radical resection of colorectal cancer were collected. LASSO regression and a random forest algorithm were used to screen the important risk factors for LNM, and a multivariate logistic regression equation and dynamic nomogram were constructed. The C index, Calibration curve, and area under the ROC curve were used to evaluate the discriminant and prediction ability of the nomogram. The net reclassification index (NRI), comprehensive discriminant improvement index (IDI), and clinical decision curve (DCA) were compared with traditional ESMO criteria to evaluate the accuracy, net benefit, and clinical practicability of the model.

RESULTS

The probability of lymph node metastasis in patients with T1 colorectal cancer was 11.17% (20/179). Multivariate analysis showed that the independent risk factors for LNM in T1 colorectal cancer were submucosal invasion depth, histological grade, CEA, lymphovascular invasion, and imaging results. The dynamic nomogram model constructed with independent risk factors has good discrimination and prediction capabilities. The C index was 0.914, the corrected C index was 0.890, the area under the ROC curve was 0.914, and the accuracy, sensitivity, and specificity were 93.3, 80.0, and 91.8%, respectively. The NRI, IDI, and DCA show that this model is superior to the ESMO standard.

CONCLUSION

This study establishes a dynamic nomogram that can effectively predict the risk of lymph node metastasis in patients with stage T1 colorectal cancer, which will provide certain help for the formulation of subsequent treatment plans for patients with stage T1 CRC after endoscopic resection.

Identification of Predictive Factors for Lymph Node Metastasis in pT1 Stage Colorectal Cancer Patients: A Retrospective Analysis Based on the Population Database

Objective: The purpose of this study was to identify predictive factors for lymph node metastasis (LNM) in pT1 stage colorectal cancer (CRC) patients. Methods: From the Surveillance, Epidemiology, and End Results (SEER) database, 2,697 consecutive pT1 stage patients who underwent surgical resection were retrospectively reviewed. Predictive factors for LNM were identified by the univariate and multivariate logistic regression analysis. The Kaplan-Meier curves and multivariate Cox regression analysis were used to evaluate the relationships between LNM and overall survival (OS) as well as cancer specific survival (CSS) of pT1 stage CRC patients. Results: The prevalence of LNM in pT1 stage CRC patients was 15.2% (410/2,697). Patient age <60 years (OR:1.869, 95% CI: 1.505-2.321, p < 0.001), poorly differentiated or mucinous or signet ring cell adenocarcinoma (OR:2.075, 95% CI: 1.584-2.717, p < 0.001), elevated carcinoembryonic antigen (CEA) level (OR:1.343, 95% CI: 1.022-1.763, p = 0.033) and perineural invasion (PNI) (OR:6.212, 95% CI: 3.502-11.017, p < 0.001) were significantly associated with LNM in pT1 stage patients. The survival analysis demonstrated that pT1 stage patients with LNM had a worse OS (5-year OS: 82.2% vs 88.7%, p = 0.020) and CSS (5-year CSS: 74.9% vs 81.5%, p = 0.041) than those without lymph node metastasis. Lymph node metastasis was an independent predictor of poor OS (HR: 1.543, 95% CI: 1.156-2.060, p = 0.003) and CSS (HR: 1.614, 95% CI: 1.121-2.324, p = 0.010) for pT1 stage colorectal cancer patients. Conclusion: Age, differentiation type, CEA level and perineural invasion were independent predictive factors for LNM in pT1 stage CRC patients. These findings might provide further risk stratification for pT1 stage patients and help clinicians identify high-risk individuals.

Tumor Location as a Prognostic Factor in T1 Colorectal Cancer

The incidence of T1 colorectal cancer is expected to increase because of the prevalence of colorectal cancer screening and the progress of endoscopic treatment such as endoscopic submucosal dissection or endoscopic full-thickness resection. Currently, the requirement for additional surgery after endoscopic resection of T1 colorectal cancer is determined according to several treatment guidelines (in USA, Europe, and Japan) referring to the following pathological findings: lymphovascular invasion, tumor differentiation, depth of invasion, and tumor budding, all of which are reported to be risk factors for lymph node metastasis. In addition to these factors, in this review, we investigate whether tumor location, which is an objective factor, has an impact on the presence of lymph node metastasis and recurrence. From recent studies, left-sided location, especially the sigmoid colon in addition to rectum, could be a risk factor for lymph node metastasis and cancer recurrence. The treatment of T1 colorectal cancer should be managed considering these findings.

Role of barium enema examination for the diagnosis of submucosal invasion depth in T1 colorectal cancers

BACKGROUND

The indication for endoscopic resection for submucosally invasive colorectal cancer (T1-CRC) depends on the preoperative diagnosis of invasion depth. The aim of this investigation was to evaluate the association between barium enema examination (BE) profile views and depth of submucosal (SM) invasion in CRCs.

METHODS

We reviewed the radiographic and endoscopic findings of 145 T1-CRCs diagnosed from 2008 to 2019. We measured the widths of horizontal and vertical rigidity under a BE profile view corresponding to CRC and compared the values with SM invasion depth. Horizontal rigidity was defined as the horizontal length and vertical rigidity as the vertical width of the barium defect corresponding to each target lesion. The most appropriate cut-off values for predicting SM invasion ≥1.8 mm were calculated by receiver operating characteristic curve analysis.

RESULTS

Values of horizontal rigidity (r = 0.626, P < 0.05) and vertical rigidity (r = 0.482, P < 0.05) correlated significantly with SM invasion depth. The most appropriate cut-off values for the prediction of SM invasion depth ≥ 1.8 mm were 4.5 mm for horizontal rigidity, with an accuracy of 80.7%; and 0.7 mm for vertical rigidity, with an accuracy of 77.9%. The prevalence of lympho-vascular invasion was significantly different when those cut-off values were applied (43.2% vs. 17.5% for horizontal rigidity, P < 0.005).

CONCLUSIONS

In T1-CRC, values of horizontal and vertical rigidities under a BE profile view were correlated with SM invasion depth. While the accuracy of the rigidities for the prediction of SM invasion depth ≥ 1.8 mm was not high, horizontal rigidity may be predictive of lympho-vascular invasion, thus aiding in therapeutic decision-making.

Multidisciplinary management of early rectal cancer - The role of surgical local excision in current and future clinical practice

The implementation of bowel cancer screening programs has led to a rise in the incidence of early rectal cancer. The combination of increased incidence and the growing interest in organ-sparing treatment options has led to an amplified importance of local excision techniques in treatment strategies for early rectal cancer. In addition, developments in new technologies of single-port surgery have popularized surgical techniques. Although local treatment of early rectal cancer seems promising, a multidisciplinary approach is necessary and awareness of the oncological robustness is warranted to enable shared decision-making. This review illustrates the position of surgical local excision in the treatment of early rectal cancer and reflects on its role in current and future clinical practice.

Risk Stratification of T1 Colorectal Cancer Metastasis to Lymph Nodes: Current Status and Perspective

With the widely spreading population-based screening programs for colorectal cancer and recent improvements in endoscopic diagnosis, the number of endoscopic resections in subjects with T1 colorectal cancer has been increasing. Some reports suggest that endoscopic resection prior to surgical resection of T1 colorectal cancer has no adverse effect on prognosis and contributes to this tendency. The decision on the need for surgical resection as an additional treatment after endoscopic resection of T1 colorectal cancer should be made according to the metastasis risk to lymph nodes based on histopathological findings. Because lymph node metastasis occurs in approximately 10% of patients with T1 colorectal cancer according to current international guidelines, the remaining 90% of patients may be at an increased risk of surgical resection and associated postoperative mortality, with no clinical benefit derived from unnecessary surgical resection. Although a more accurate prediction system for lymph node metastasis is needed to solve this problem, risk stratification for lymph node metastasis remains controversial. In this review, we focus on the current status of risk stratification of T1 colorectal cancer metastasis to lymph nodes and outline future perspectives.

The essential problem of over-measuring the depth of submucosal invasion in pT1 colorectal cancer

A depth of submucosal invasion (DSI) of ≥1000 μm is an important risk factor for lymph node metastasis (LNM) in patients with submucosal invasive (pT1) colorectal cancer (CRC), according to the European Society of Gastrointestinal Endoscopy and the Japanese Society for Cancer of the Colon and Rectum (JSCCR) guidelines. According to the latter, if the location of the muscularis mucosae in the invasive area is not confirmed, the DSI can be measured from the surface. In these cases, a 'remaining intramucosal lesion' (rIL), which is in the invasive area, is sometimes observed. To avoid over-measuring the DSI, we proposed a 'modified DSI' (mDSI), which excludes the rIL from the JSCCR DSI. We investigated the characteristics and effectiveness of the rIL and mDSI by grouping cases with polypoid growth (PG) and non-polypoid growth (NPG) histologically. Three hundred and thirty-nine consecutive patients with pT1 CRC were examined. LNM was detected in 37 cases. The distribution of the DSI and rIL was significantly higher in PG than in NPG cases (P<0.001). There was no difference in the mDSI distribution between the PG-/NPG-type cases. An rIL was observed in 39% (127/301) of cases, in which the location of the muscularis mucosae could not be determined or estimated and the mDIS could be estimated. In 13% (16/127) of cases, the mDSI was effective (JSCCR DSI ≥1000 and mDSI <1000 μm). Among these 16 cases, 11 (69%) did not have risk factors (mDSI, lymphovascular invasion, budding grade, or special histological types) and may have avoided unnecessary surgery.

Predictors of lymph-node metastasis in surgically resected T1 colorectal cancer in Western populations

Background

The risk of lymph-node metastasis (LNM) in T1 colorectal cancer (CRC) has not been well documented in heterogeneous Western populations. This study investigated the predictors of LNM and the long-term outcomes of patients by analysing T1 CRC surgical specimens and patients’ demographic data.

Methods

Patients with surgically resected T1 CRC between 2004 and 2014 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. Patients with multiple primary cancers, with neoadjuvant therapy, or without a confirmed histopathological diagnosis were excluded. Multivariate logistic-regression analysis was used to identify the predictors of LNM.

Results

Of the 22,319 patients, 10.6% had a positive lymph-node status based on the final pathology (nodal category: N1 9.6%, N2 1.0%). Younger age, female sex, Asian or African-American ethnicity, poor differentiation, and tumor site outside the rectum were significantly associated with LNM. Subgroup analyses for patients stratified by tumor site suggested that the rate of positive lymph-node status was the lowest in the rectum (hazard ratio: 0.74; 95% confidence interval: 0.63–0.86).

Conclusion

The risk of LNM was potentially lower in Caucasian patients than in API or African-American patients with surgically resected T1 CRC. Regarding the T1 CRC site, the rectum was associated with a lower risk of LNM.

Clinical and endoscopic characteristics of post-colonoscopy colorectal cancers detected within 10 years after a previous negative examination

Background and study aims We sometimes encounter colorectal cancer (CRC) that is discovered during the time interval between initial colonoscopy and the recommended follow-up examination. Although several studies reported such cases of CRC, most were based on registry data, which implied that the endoscopic quality was not consistent or guaranteed. We aimed to clarify these clinical and endoscopic characteristics at our high-volume center where a retrospective survey could be precisely performed.

Patients and methods We retrospectively analyzed patients with CRC who underwent endoscopic resection or surgery from April 2002 to December 2010, categorizing them into two groups: a “study group” of patients with a negative colonoscopy during the previous 10 years, and a “control group” of patients without a previous colonoscopy or with a previous colonoscopy more than 10 years prior.

Results A total of 2042 patients had CRC, among which 55 patients were classified into the study group and the remaining 1989 into the control group. The CRC cases in the study group showed a significant association with smaller (< 30 mm) tumor size (odds ratio [OR] 2.3; 95 % confidence interval [CI] 1.3–4.0) and proximal tumor site (OR 1.7; 95 %CI 0.9–2.9). In addition, right-sided and depressed-type T1 CRCs were significantly more common in the study group.

Conclusions Tumor size and location were associated with CRCs detected within 10 years after the negative examination. In addition, depressed-type T1 CRCs were more common. Therefore, we should pay more attention to small, right-sided, or depressed-type tumors in daily colonoscopy.

Classic and Novel Histopathologic Risk Factors for Lymph Node Metastasis in T1 Colorectal Cancer: A Systematic Review and Meta-analysis

BACKGROUND

Treatment of endoscopically resected T1 colorectal cancers is based on the risk of lymph node metastasis. Risk is based on histopathologic features, although there is lack of consensus as to what constitutes high-risk features.

OBJECTIVE

The purpose of this study was to conduct a systematic review and meta-analysis of histopathologic risk factors for lymph node metastasis.

DATA SOURCES

A search of MEDLINE, Embase, Scopus, and Cochrane controlled register of trials for risk factors for lymph node metastasis was performed from inception until August 2018.

STUDY SELECTION

Included patients must have had an oncologic resection to confirm lymph node status and reported at least 1 histopathologic risk factor.

INTERVENTION

Rates of lymph node positivity were compared between patients with and without risk factors.

MAIN OUTCOME MEASURES

We report the results of the meta-analysis as ORs.

RESULTS

Of 8592 citations, 60 met inclusion criteria. Pooled analyses found that lymphovascular invasion, vascular invasion, neural invasion, and poorly differentiated histology were significantly associated with lymph node metastasis, as were depths of 1000 µm (OR = 2.76), 1500 µm (OR = 4.37), 2000 µm (OR = 2.37), submucosal level 3 depth (OR = 3.08), and submucosal level 2/3 (OR = 3.08) depth. Depth of 3000 µm, Haggitt level 4, and widths of 3000 µm and 4000 µm were not significantly associated with lymph node metastasis. Tumor budding (OR = 4.99) and poorly differentiated clusters (OR = 14.61) were also significantly associated with lymph node metastasis.

LIMITATIONS

Included studies reported risk factors independently, making it impossible to examine the additive metastasis risk in patients with numerous risk factors.

CONCLUSIONS

We identified 1500 μm as the depth most significantly associated with lymph node metastasis. Novel factors tumor budding and poorly differentiated clusters were also significantly associated with lymph node metastasis. These findings should help inform guidelines regarding risk stratification of T1 tumors and prompt additional investigation into the exact contribution of poorly differentiated clusters to lymph node metastasis.

Activated macrophages promote invasion by early colorectal cancer via an interleukin 1β-serum amyloid A1 axis

Submucosal invasion and lymph node metastasis are important issues affecting treatment options for early colorectal cancer (CRC). In this study, we aimed to unravel the molecular mechanism underlying the invasiveness of early CRCs. We performed RNA‐sequencing (RNA‐seq) with poorly differentiated components (PORs) and their normal counterparts isolated from T1 CRC tissues and detected significant upregulation of serum amyloid A1 (SAA1) in PORs. Immunohistochemical analysis revealed that SAA1 was specifically expressed in PORs at the invasive front of T1b CRCs. Upregulation of SAA1 in CRC cells promoted cell migration and invasion. Coculture experiments using CRC cell lines and THP‐1 cells suggested that interleukin 1β (IL‐1β) produced by macrophages induces SAA1 expression in CRC cells. Induction of SAA1 and promotion of CRC cell migration and invasion by macrophages were inhibited by blocking IL‐1β. These findings were supported by immunohistochemical analysis of primary T1 CRCs showing accumulation of M1‐like/M2‐like macrophages at SAA1‐positive invasive front regions. Moreover, SAA1 produced by CRC cells stimulated upregulation of matrix metalloproteinase‐9 in macrophages. Our data suggest that tumor‐associated macrophages at the invasive front of early CRCs promote cancer cell migration and invasion through induction of SAA1 and that SAA1 may be a predictive biomarker and a useful therapeutic target.

Histopathological risk factors for lymph node metastases in T1 colorectal cancer: meta-analysis

BACKGROUND

National screening programmes increase the proportion of T1 colorectal cancers. Local excision may be possible, but the risk of lymph node metastases (LNMs) could jeopardize long-term outcomes. The aim of the present study was to review the association between histopathological findings and LNMs in T1 colorectal cancer.

METHODS

A systematic literature search was conducted using PubMed,Embase, and Cochrane online databases. Studies investigating the association between one or more histopathological factors and LNMs in patients who underwent resection for T1 colorectal cancer were included.

RESULTS

Sixteen observational studies were included in the meta-analysis, including a total of 10 181 patients, of whom 1 307 had LNMs. Lymphovascular invasion (odds ratio (OR) 7.42; P < 0.001), tumour budding (OR 4.00; P < 0.001), depth of submucosal invasion, whether measured as at least 1000 µm (OR 3.53; P < 0.001) or Sm2-3 (OR 2.12; P = 0.020), high tumour grade (OR 3.75; P < 0.001), polypoid growth pattern (OR 1.59; P = 0.040), and rectal location of tumour (OR 1.36; P = 0.003) were associated with LNMs.

CONCLUSION

Distinct histopathological factors associated with nodal metastases in T1 colorectal cancer can aid selection of patients for local excision or major excisional surgery.

Development and validation of a nomogram for further decision of radical surgery in pT1 colorectal cancer after local resection

PURPOSE

The aim of this study was to develop and validate a nomogram to assist physicians making further decisions on the requirement of a radical surgery for T1 colorectal cancer (CRC) after local excision through preoperative prediction of lymph node metastasis (LNM).

METHODS

A total of 141 T1 CRC patients were enrolled from January 2013 to August 2020. The independent predictive parameters were determined in multivariate analyses. The nomogram was constructed based on predictors of LNM and its performance was evaluated with respect to its calibration, discrimination, and decision curve analysis. Internal validation by bootstrapping was performed to verify the applicability of the nomogram.

RESULTS

cN in CT/MRI (N+), histologic type (poorly differentiated, mucinous adenocarcinoma, and signet-ring cell carcinoma), tumor budding (G3), and lymphovascular invasion were identified in the multivariable analysis (p<0.05). The developed nomogram incorporated these four predictors and it yielded good discrimination and calibration, with an area under the curve (AUC) of 0.89 (95% confidence interval [CI]: 0.80-0.97). However, the Japanese guideline yielded an AUC of 0.75 (95% CI: 0.63-0.87). A decision curve analysis showed that the predictive scoring system had a high clinical application value, and the nomogram conferred a greater benefit than the Japanese guideline did (range of threshold within 10%-80%).

CONCLUSIONS

This study proposed a novel predictive model to assist physicians in making treatment decisions regarding additional surgery after local excision.

Risk Factors for Lymph Node Metastasis in Pathological T1b Colorectal Cancer

BACKGROUND/AIM

The rate of lymph node metastasis (LNM) of colorectal carcinoma (CRC) with a submucosal (SM) invasion depth of 1000 µm or more can reach 12.5%, which is the most common reason for additional resection in daily practice. Other studies have reported that the rate of LNM is less than 2%, regardless of the depth of invasion, if the lesions show good histology, lymphovascular infiltration is negative, and tumor budding is limited. The purpose of this study was to investigate new risk factors for LNM in T1b colorectal cancer.

PATIENTS AND METHODS

The 239 patients who were diagnosed with pathological T1b CRC after colorectal surgical resection at the Osaka Police Hospital in Japan between January 2008 and December 2018 were retrospectively reviewed in this study.

RESULTS

The LNM rate was 11.3% (27/239). The variables identified as being significant factors using multivariate analysis were: i) lymphatic invasion (Ly)-positive [odds ratio (OR)=5.97; 95% confidence interval (CI)=2.27-15.74], ii) female gender (OR=3.49; 95%CI=1.38-8.85), and iii) left-sided colorectal involvement (OR=4.98; 95%CI=1.22-20.39). If none of these risk factors were present with T1b, the LNM rate was 0% (0/28).

CONCLUSIONS

Ly-positive, female gender, and left-sided colorectal involvement could be risk factors for LNM in T1b CRC.

Clinical significance of immunohistochemical lymphovascular evaluation to determine additional surgery after endoscopic submucosal dissection for colorectal T1 carcinoma

PURPOSE

The Japanese Society for Cancer of the Colon and Rectum (JSCCR) guidelines indicate lymphovascular invasion-evaluated by hematoxylin and eosin (HE) staining-as a surgical requirement after endoscopic submucosal dissection (ESD) in T1 colorectal carcinoma (CRC) patients; however, immunohistochemical evaluation may be superior. This study aimed to clarify the significance of immunohistochemical lymphovascular evaluation as an indicator for additional surgery of T1 CRC after ESD, and assessed the guidelines' adequacy, even when evaluating through immunostaining.

METHODS

Patients with T1 CRC who underwent ESD were enrolled across three institutions between January 2012 and December 2017. Immunohistochemical lymphovascular evaluation was performed. Clinicopathological features, pathological evaluations, and surgery indications were recorded. Univariate and multivariate logistic regression identified risk factors for lymph node (LN) metastasis of T1 CRC after ESD.

RESULTS

Among 370 patients with T1 CRC, recurrence, 5-year overall survival, and 5-year disease specific survival rates were 1.6%, 94.6%, and 99.5%, respectively. Six patients (1.6%) experienced recurrence, five of whom underwent additional surgery. Those with no risk factors did not exhibit recurrence. A total of 215 (58.1%) patients underwent additional surgery after ESD, 21 (9.7%) of whom exhibited LN metastasis. Among 16 patients who underwent additional surgery due to lymphovascular invasion, three (18.8%) had LN metastasis. Multivariate logistic regression analysis identified lymphatic invasion as a significant risk factor for LN metastasis (odds ratio 3.9, 95% confidence interval 1.0-14.6, P = 0.0421).

CONCLUSIONS

The JSCCR guidelines have clinical validity, and immunohistochemical lymphatic evaluation findings potentially predict LN metastasis for T1 CRC after ESD.

Artificial Intelligence System to Determine Risk of T1 Colorectal Cancer Metastasis to Lymph Node

BACKGROUND & AIMS

In accordance with guidelines, most patients with T1 colorectal cancers (CRC) undergo surgical resection with lymph node dissection, despite the low incidence (∼10%) of metastasis to lymph nodes. To reduce unnecessary surgical resections, we used artificial intelligence to build a model to identify T1 colorectal tumors at risk for metastasis to lymph node and validated the model in a separate set of patients.

METHODS

We collected data from 3134 patients with T1 CRC treated at 6 hospitals in Japan from April 1997 through September 2017 (training cohort). We developed a machine-learning artificial neural network (ANN) using data on patients' age and sex, as well as tumor size, location, morphology, lymphatic and vascular invasion, and histologic grade. We then conducted the external validation on the ANN model using independent 939 patients at another hospital during the same period (validation cohort). We calculated areas under the receiver operator characteristics curves (AUCs) for the ability of the model and US guidelines to identify patients with lymph node metastases.

RESULTS

Lymph node metastases were found in 319 (10.2%) of 3134 patients in the training cohort and 79 (8.4%) of /939 patients in the validation cohort. In the validation cohort, the ANN model identified patients with lymph node metastases with an AUC of 0.83, whereas the guidelines identified patients with lymph node metastases with an AUC of 0.73 (P < .001). When the analysis was limited to patients with initial endoscopic resection (n = 517), the ANN model identified patients with lymph node metastases with an AUC of 0.84 and the guidelines identified these patients with an AUC of 0.77 (P = .005).

CONCLUSIONS

The ANN model outperformed guidelines in identifying patients with T1 CRCs who had lymph node metastases. This model might be used to determine which patients require additional surgery after endoscopic resection of T1 CRCs. UMIN Clinical Trials Registry no: UMIN000038609.

Artificial intelligence in gastrointestinal endoscopy: general overview

Artificial intelligence (AI) is now a trendy subject in clinical medicine and especially in gastrointestinal (GI) endoscopy. AI has the potential to improve the quality of GI endoscopy at all levels. It will compensate for humans' errors and limited capabilities by bringing more accuracy, consistency, and higher speed, making endoscopic procedures more efficient and of higher quality. AI showed great results in diagnostic and therapeutic endoscopy in all parts of the GI tract. More studies are still needed before the introduction of this new technology in our daily practice and clinical guidelines. Furthermore, ethical clearance and new legislations might be needed. In conclusion, the introduction of AI will be a big breakthrough in the field of GI endoscopy in the upcoming years. It has the potential to bring major improvements to GI endoscopy at all levels.

Offerhaus G, Siersema PD, Tollenaar RAEM, Hardwick JCH, Hawinkels LJAC, Moons LMG, Lacle MM, Mesker WE, Boonstra JJ. Tumour-stroma ratio has poor prognostic value in non-pedunculated T1 colorectal cancer: A multi-centre case-cohort study

BACKGROUND

Current risk stratification models for early invasive (T1) colorectal cancer are not able to discriminate accurately between prognostic favourable and unfavourable tumours, resulting in over-treatment of a large (>80%) proportion of T1 colorectal cancer patients. The tumour-stroma ratio (TSR), which is a measure for the relative amount of desmoplastic tumour stroma, is reported to be a strong independent prognostic factor in advanced-stage colorectal cancer, with a high stromal content being associated with worse prognosis and survival. We aimed to investigate whether the TSR predicts clinical outcome in patients with non-pedunculated T1 colorectal cancer.

METHODS

Hematoxylin and eosin (H&E)-stained tumour tissue slides from a retrospective multi-centre case cohort of patients with non-pedunculated surgically treated T1 colorectal cancer were assessed for TSR by two independent observers who were blinded for clinical outcomes. The primary end point was adverse outcome, which was defined as the presence of lymph node metastasis in the resection specimen or colorectal cancer recurrence during follow-up.

RESULTS

All 261 patients in the case cohort had H&E slides available for TSR scoring. Of these, 183 were scored as stroma-low, and 78 were scored as stroma-high. There was moderate inter-observer agreement (κ = 0.42). In total, 41 patients had lymph node metastasis, 17 patients had recurrent cancer and five had both. Stroma-high tumours were not associated with an increased risk for an adverse outcome (adjusted hazard ratio = 0.66, 95% confidence interval 0.37-1.18; p = 0.163).

CONCLUSIONS

Our study emphasises that existing prognosticators may not be simply extrapolated to T1 colorectal cancers, even though their prognostic value has been widely validated in more advanced-stage tumours.

Long-term Outcomes of Primary Endoscopic Resection vs Surgery for T1 Colorectal Cancer: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

There is controversy over the best therapeutic approach for T1 colorectal cancer. We performed a systematic review and meta-analysis of long-term outcomes of endoscopic resection (ER) vs those of primary or additional surgery.

METHODS

We performed a systematic review of the PubMed, Embase, and Cochrane databases through October 2019 for studies that reported outcomes (overall survival, disease-specific survival, recurrence-free survival at 5 years, recurrence, and metastasis) of ER vs surgery in patients with colorectal neoplasms. Hazard ratios (HR) were calculated based on time to events.

RESULTS

In total, 17 published studies with 19,979 patients were included. The median follow-up time among the studies was 36 months. The meta-analysis found no significant differences between primary ER and primary surgery in overall survival (79.6% vs 82.1%, HR, 1.10; 95% CI, 0.84-1.45), recurrence-free survival (96.0% vs 96.7%, HR, 1.28; 95% CI, 0.87-1.88), or disease-specific survival (94.8% vs 96.5%; HR, 1.09; 95% CI, 0.67-1.78). Additional surgery and primary surgery did not produce significant differences in recurrence-free survival (HR, 1.27; 95% CI, 0.85-1.89). A significantly lower proportion of patients who underwent primary ER had procedure-related adverse events (2.3%) than patients who underwent primary surgery (10.9%) (P < .001). Lymphovascular invasion and rectal cancer, but not depth of submucosal invasion, were independently associated with recurrence for all T1 colorectal cancers.

CONCLUSIONS

In a systematic review and meta-analysis, we found that ER should be considered as the first-line treatment for endoscopically resectable T1 colorectal cancers. In cases of noncurative resection, additional surgery can have comparable outcomes to primary surgery.