Clinicopathological characteristics of T1 colorectal cancer without background adenoma

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.

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.

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.

Subpopulation analysis of survival in high-risk T1 colorectal cancer: surgery versus endoscopic resection only

BACKGROUND AND AIMS

This study aimed to assess the long-term survival of patients with T1 colorectal cancer (CRC) after local or surgical resection considering the type and number of risk factors for lymph node metastasis.

METHODS

This study included patients with high-risk T1 CRC who underwent therapeutic resection at the National Cancer Center, Korea between January 2001 and December 2014. Risk factors included positive resection margin, high-grade histology, deep submucosal invasion, vascular invasion, budding, and no background adenoma (BGA). We statistically divided the population into favorable or unfavorable subpopulations. The favorable subpopulation included the following 5 combinations of risk factors: positive margin only or unconditional for margin status, deep submucosal invasion only, budding only, no BGA only, and budding + no BGA. We analyzed the survival rate according to the resection type (local or surgical) in the total cohort and in each subpopulation.

RESULTS

Eighty-one and 466 patients underwent local and surgical resections, respectively. The distant recurrence-free survival (DRFS) and overall survival (OS) rates were significantly high in the surgical group (hazard ratio [HR], .20; 95% confidence interval [CI], .06-.61; P = .0045 and HR, .41; 95% CI, .25-.70; P = .0010, respectively). In the favorable subpopulation, both DRFS and OS rates were not significantly different between the surgical and local groups (HR, .26; 95% CI, .02-4.19; P = .3431 and HR, .58; 95% CI, .27-1.23; P = .1534, respectively).

CONCLUSIONS

Intensive surveillance without additional surgery may be another option in selected cases after of high-risk T1 CRC endoscopic resection.

Transanal endoscopic microsurgical submucosal dissection (TEM-ESD): A novel approach to the local treatment of early rectal cancer

BACKGROUND

Complete local resection is currently the treatment of choice for low-risk early rectal cancer; however, the ideal resection technique for such tumours is still debated. Transanal endoscopic microsurgical submucosal dissection (TEM-ESD) is a new technique which combines the ergonomic advantages of transanal endoscopic microsurgery (TEM) with the minimally invasive approach of endoscopic submucosal dissection (ESD). The aim of our study was to assess the feasibility, safety, and long-term outcomes of TEM-ESD in treating early rectal cancer.

MATERIALS AND METHODS

We retrospectively analysed all cases of rectal adenocarcinomas treated with TEM-ESD in Karlsruhe Municipal Hospital between 2012 and 2019, as well as the perioperative and follow-up data of the patients.

RESULTS

We identified 40 cases (19 low-risk and 21 high-risk carcinomas) matching our criteria. The median size of the lesions was 3.8 cm and the median operating time 48.5 min. En bloc resection was possible in all cases, while histologically complete resection was confirmed in 18 of 19 low-risk tumours and in 30 out of all lesions. The resection was curative in 19 cases. No scarring of the mesorectum was reported during the completion of total mesorectal excision for high-risk tumours. There was only 1 case of local recurrence among patients treated with curative intent, with an overall survival rate of 100% and a disease-free survival rate of 96% at both 2 and 5 years for these patients.

CONCLUSION

TEM-ESD is a safe and feasible therapeutic option for resecting early rectal cancer, offering very good long-term outcomes.

Characteristics of minute T1 colorectal cancer in relevance to pathology and treatment

Purpose

Minute T1 colorectal cancer (CRC) lesions (≤5 mm) are rare; however, little is known about their characteristics and aggressiveness. In this study, we evaluated the characteristics of minute T1 CRC in relevance to pathology and treatment.

Methods

This retrospective study included 849 patients with T1 CRC endoscopically or surgically treated between January 2001 and December 2016. The patients were stratified into 4 groups according to tumor size; minute group (≤5 mm), small group (6–10 mm), medium group (11–20 mm), and large group (≥21 mm). Clinicopathological variables were evaluated with respect to tumor size.

Results

The incidence of the minute T1 CRC was 2.4% (20 of 849). Minute T1 CRC was significantly associated with flat type (minute, 25%; small, 12.6%; medium, 8.8%; large, 12.6%; P = 0.016), right-sided cancer (30%, 15.4%, 15.4%, 15.1%, P = 0.002) and the absence of background adenoma (BGA) (50%, 40.7%, 32.8%, 18.1%, P < 0.001). In patients who underwent surgery, lymph node metastasis (LNM) was significantly higher in the minute group (36.4%, 15.9%, 15.7%, 9.2%, P = 0.029).

Conclusion

Minute T1 CRC is significantly associated with flat type, right-sided cancers, as well as with the absence of BGA and LNM. These results suggested the minute T1 CRC lesions are often aggressive and are likely to be missed during colonoscopy.

Nomogram Development and External Validation for Predicting the Risk of Lymph Node Metastasis in T1 Colorectal Cancer

PURPOSE

Predicting lymph node metastasis (LNM) risk is crucial in determining further treatment strategies following endoscopic resection of T1 colorectal cancer (CRC). This study aimed to establish a new prediction model for the risk of LNM in T1 CRC patients.

MATERIALS AND METHODS

The development set included 833 patients with T1 CRC who had undergone endoscopic (n=154) or surgical (n=679) resection at the National Cancer Center. The validation set included 722 T1 CRC patients who had undergone endoscopic (n=249) or surgical (n=473) resection at Daehang Hospital. A logistic regression model was used to construct the prediction model. To assess the performance of prediction model, discrimination was evaluated using the receiver operating characteristic (ROC) curves with area under the ROC curve (AUC), and calibration was assessed using the Hosmer-Lemeshow (HL) goodness-of-fit test.

RESULTS

Five independent risk factors were determined in the multivariable model, including vascular invasion, high-grade histology, submucosal invasion, budding, and background adenoma. In final prediction model, the performance of the model was good that the AUC was 0.812 (95% confidence interval [CI], 0.770 to 0.855) and the HL chi-squared test statistic was 1.266 (p=0.737). In external validation, the performance was still good that the AUC was 0.771 (95% CI, 0.708 to 0.834) and the p-value of the HL chi-squared test was 0.040. We constructed the nomogram with the final prediction model.

CONCLUSION

We presented an externally validated new prediction model for LNM risk in T1 CRC patients, guiding decision making in determining whether additional surgery is required after endoscopic resection of T1 CRC.

Tumor size as a prognostic factor in patients with stage IIa colon cancer

BACKGROUND

The aim of this study was to identify stage II colon cancer patients with a high risk of recurrence.

METHODS

All patients who underwent surgery for stage II colon cancer (CC) were retrospectively enrolled and sub-grouped according to TNM staging (IIa-b-c) and stage IIa in high (IIaHR) and low risk (IIaLR) according to pathologic features. The primary outcomes measured were the 5-year overall survival (OS) and disease-free survival (DFS).

RESULTS

A total of 214 patients were reviewed. Only a maximum tumor diameter<4 cm in the IIaLR group was associated with a higher recurrence rate than a large tumor size (5-year DFS 71.7%vs.87.6%, p = 0.028). The DFS in the large IIaLR CC group was better than that in the IIaHR and IIb-c groups (5-year DFS: 92.7%vs.79.3%, p = 0.023). In contrast, the recurrence rate in the small IIaLR CC group was similar to that in the IIaHR, IIb-c stage CC group.

CONCLUSIONS

In stage IIa CC evaluation of the tumor size as a prognostic factor may help identify patients who could benefit from additional postoperative therapy.