pT1 Colorectal Cancer Research Articles

Update on the management of pT1 colorectal cancer

Abstract With the implementation of CRC screening programs, the incidence of pT1 CRC has increased significantly: up to 40% of colon tumors detected in screening colonoscopies are pT1. Traditionally, the treatment of choice for CRC is surgery with lymph node resection, but pT1 CRC has a very good prognosis with 5-year disease-free survival rates greater than 90% and thanks to advanced endoscopy, it can be treated locally with a minimally invasive approach in many cases. After resection of the lesion, an adequate histological description of the specimen will guide us to make the final decision in the management of pT1 CRC: whether endoscopic resection is considered curative or whether additional surgery will be required to prevent local recurrence, lymphatic dissemination and /or distant metastasis. The decision to proceed with additional surgery or surveillance depends primarily on the estimated oncologic benefit of surgery, operative risk, and patient preferences. It must be taken into account that colorectal surgery carries a significant risk of morbidity and mortality for elderly patients. Currently we base our decisions on histological criteria, but the natural history of pT1 CRC resected by endoscopy is really unknown and there are not enough quality prospective studies with results after long-term follow-up of pT1 CRC non-surgically managed, especially in the case of high-risk pT1, which would explain the great variability in the management of these patients. In this thematic review we have analyzed the current state of management of pT1 CRC in the field of endoscopic diagnosis and treatment, histological evaluation and its prognostic implications. We have also reviewed the most recent evidence regarding surveillance: how to carry out adequate follow-up and determine the optimal frequency and the most appropriate surveillance method after local resection of pT1 CRC.

Association of circulating tumor DNA (ctDNA) molecular disease (MRD) detection with lymph node metastasis after local excision of pathological T1 colorectal cancer: First results from DENEB, a CIRCULATE-Japan GALAXY substudy.

23 Background: Patients with pathological T1 (pT1) colorectal cancer (CRC) at high risk for lymph node metastasis (LNM) after complete local resection are recommended to receive additional intestinal resection along with lymph node dissection. However, the existing pathological criteria for risk stratification of LNM are inadequate, such that ~90% of patients without LNM are exposed to potentially unnecessary treatment. Based on the CIRCULATE-Japan platform, we launched DENEB, a new prospective substudy within the GALAXY observational study, to explore the ability of predicting LNM using circulating tumor DNA (ctDNA) detection compared to the standard pathological criteria. Methods: This study included patients with pT1 CRC who underwent complete local resection and were scheduled for additional intestinal resection with lymph node dissection based on the standard pathologic risk-stratification criteria for LNM. The additional surgery was indicated for patients meeting any of the following criteria: (1) depth of submucosal invasion (>1000µm); (2) lymphovascular invasion; (3) poorly differentiated adenocarcinoma, signet-ring cell carcinoma, or mucinous carcinoma; and (4) high-grade tumor budding (BD2/3) at the site of deepest invasion according to the Japanese guideline. ctDNA was analyzed from plasma samples collected within 4 weeks before the additional intestinal resection using a personalized, tumor-informed assay (Signatera bespoke multiplex-PCR NGS assay). The study assessed the diagnostic concordance rate between ctDNA detection and the occurrence of LNM. Results: Of 208 CRC patients enrolled between July 2021 and May 2023 in DENEB, 166 patients met the inclusion criteria. Of these, 22 (13.3%) were ultimately diagnosed with pStage III due to the presence of LNM in additional intestinal resection. Among the 166 patients, 6 patients tested ctDNA-positive; all 6 had LNM, yielding a positive predictive value of 100.0%. On the other hand, 160 patients had ctDNA-negative results, 144 of whom did not have LNM, resulting in a negative predictive value of 90.0%. The overall diagnostic concordance rate for ctDNA in detecting LNM was 90.4% (95% confidence interval, 84.8% to 94.4%). All 6 patients with a ctDNA-positive result and LNM had left-sided colorectal cancer and a tumor diameter greater than 13 mm. Conclusions: This analysis showed that ctDNA testing has the potential to improve risk stratification of LNM in patients with pT1 CRC who underwent complete local resection. Clinical trial information: UMIN000039205 .

Are the width, length, depth, and area of submucosal invasion predictive of lymph node metastasis in pT1 colorectal cancer?

Submucosa-limited (pathological T1, pT1) colorectal cancers (CRCs) pose a continuing challenge in the choice of treatment options, which range from local excision to radical surgery. The aim of this study was to evaluate the morphometric and morphologic risk factors associated with regional lymph node metastasis (LNM) in pT1 CRC. We performed a histological review of patients who underwent oncological resection between 2016 and 2022. Tumor grade, budding, poorly differentiated clusters (PDCs), cancer gland rupture, lymphovascular invasion (LVI), and presence of deep submucosal invasion (DSI), as well as width, length, total area, and area of DSI, were evaluated as potential risk factors for LNM. A total of 264 cases of colon and rectal carcinomas with invasion into the submucosal layer (pT1) were identified. LNM was found in 46 of the 264 cases (17.4%). All morphometric parameters, as well as DSI (P=0.330), showed no significant association with LNM. High grade adenocarcinoma (P=0.050), budding (P=0.056), and PDCs (P<0.001) were associated with LNM. In the multivariate analysis, LVI presence remained the only significant independent risk factor (odds ratio, 15.7; 95% confidence interval, 8.5-94.9; P<0.001). The DSI of T1 CRC, as well as other morphometric parameters of submucosal tumor spread, held no predictive value in terms of LNM. LVI was the only independent risk factor of LNM.

Prediction of disease recurrence or residual disease after primary endoscopic resection of pT1 colorectal cancer—results from a large nationwide Danish study

PurposeRisk assessment of disease recurrence in pT1 colorectal cancer is crucial in order to select the appropriate treatment strategy. The study aimed to develop a prediction model, based on histopathological data, for the probability of disease recurrence and residual disease in patients with pT1 colorectal cancer.MethodsThe model dataset consisted of 558 patients with pT1 CRC who had undergone endoscopic resection only (n = 339) or endoscopic resection followed by subsequent bowel resection (n = 219). Tissue blocks and slides were retrieved from Pathology Departments from all regions in Denmark. All original slides were evaluated by one experienced gastrointestinal pathologist (TPK). New sections were cut and stained for haematoxylin and eosin (HE) and immunohistochemical markers. Missing values were multiple imputed. A logistic regression model with backward elimination was used to construct the prediction model.ResultsThe final prediction model for disease recurrence demonstrated good performance with AUC of 0.75 [95% CI 0.72–0.78], HL chi-squared test of 0.59 and scaled Brier score of 10%. The final prediction model for residual disease demonstrated medium performance with an AUC of 0.68 [0.63–0.72].ConclusionWe developed a prediction model for the probability of disease recurrence in pT1 CRC with good performance and calibration based on histopathological data. Together with lymphatic and venous invasion, an involved resection margin (0 mm) as opposed to a margin of ≤ 1 mm was an independent risk factor for both disease recurrence and residual disease.

Management of pT1 CRC detected on the colorectal cancer screening programme (Basque Country. Spain)

Abstract Background The Bowel Cancer Screening Programme (BCSP) started in 2009 with faecal immunochemical test (FIT, with cut-off 20µg/g faeces) every 2 years (for 50-69 year- olds). 2.518.715 people were invited until 2021. Participation rate was 70.4% with 5.3% positive rate and 92.7% adherence to colonoscopy. Colorectal cancer (CRC) detection rate was 2.28 ‰ with 70.6% found in initial stage. The PT1 (stage I) represented 40% of the total cancer detected (4,050 in the overall period). Objectives To compare the characteristics and management of pT1 CRC. Methods Retrospective cohort study including pT1 CRC Stage I diagnosed after colonoscopy in positive FIT from 2009-2017. Variables: sex, age groups, endoscopic and surgical treatment, CRC recurrence and survival. Chi-square, Logistic Regression, SPSS v.23. Results Of the 1,523 CRC detected, 585 were detected as pT1 and I stage (38.4%). 73.4% in men and by age group 59% over 60 years-old. 48.5% were treated with surgery and 51.5% with endoscopic resection. No significant differences were found adjusted by sex and age regardless of treatment. In 57.6% of patients under surgery, CRC was not reported by pathological analysis. All cases followed up by colonoscopy with variability in the number of surveillances over time. 4.1% (24) had CRC recurrence with 87% detected in the surveillance, no significant differences regardless of the treatment. 1.5% (9) died due to CRC progression. Conclusions Apart from the high number of CRC detected in early stages by the screening Programme, an important number of cases are reported as pT1 CRC. Endoscopic resection is one of the treatments of choice without significant impact either in recurrence of neoplasia or mortality. However, surgical procedure shows overtreatment because of the high number of cases without CRC after the procedure. Therefore, endoscopic resection could be the main choice to treat pT1 CRC. Key messages • Endoscopic resection is one of the treatment of choice without impact in recurrence for the pT1 CRC detected through the BCSP. • The Basque BCSP obtains excellent participation rate, reflected in early detection and treatment of pre and malignant lesions.

Dilemmas in the Clinical Management of pT1 Colorectal Cancer.

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

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

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

Low PD-L1 expression in immune cells predicts the presence of nodal metastasis in early invasive (pT1) colorectal cancer: a novel tool to tailor surgical treatment.

The current criteria for surgical treatment after endoscopic resection of a pT1 colorectal carcinoma (CRC) are unsatisfactory because nodal involvement is rarely present. This study investigates the correlation between PD-L1 expression and nodal metastasis in pT1 CRCs to enable its use for tailoring surgical treatment after endoscopic removal. Histopathological features of 81 surgically resected pT1 CRC, 19 metastatic and 62 non-metastatic cases were assessed. PD-L1 expression was evaluated by immunohistochemistry (clone 22C3) and independently assessed by two pathologists using tumour proportion score (TPS), combined positive score (CPS) and immune cell score (ICS). The correlation between PD-L1 expression and nodal metastasis, the optimal cut-off values, interobserver agreement and impact upon patients' surgical management were determined. PD-L1 expression in termsof CPS and ICS independently correlated with lymph node metastasis (PD-L1CPS : OR = -2.5, 95% CI = -4.11 to -0.97, P = 0.008 and PD-L1ICS : OR = -1.85, 95% CI = -2.90 to -0.79, P = 0.004) and < 1.2 CPS and <1.3% ICS were identified as the optimal cut-off values to discriminate between metastatic and non-metastatic patients. In our cohort, the implementation of these cut-off values would have avoided a significant rate of unnecessary surgeries in pN0 patients (PD-L1CPS = 43.2; PD-L1ICS = 51.9%). Ultimately, PD-L1 evaluation showed good interpathologist concordance in absolute terms [PD-L1CPS interclass correlation coefficient (ICC) = 0.91; PD-L1ICS ICC = 0.793] and using the identified cut-off values (PD-L1CPS ICC = 0.848; PD-L1ICS ICC = 0.756). Our study shows that PD-L1 expression is an effective predictor of nodal status and could improve patient selection for surgery after endoscopic removal of pT1 CRCs.

Risk Factors for Lymph Node Metastasis and Recurrence in T1 Colorectal Cancer: Analysis of 801 Patients in a Single Institute.

To identify risk factors for lymph node metastasis and postoperative recurrence of pT1 colorectal cancer by clinicopathological study of surgically resected cases. In 801 patients with pT1 colorectal cancer who underwent surgical resection with lymph node dissection between April 2007 and January 2021, we evaluated clinicopathological factors (age, gender, BMI, serum CEA level, tumor localization, additional resection after endoscopic treatment, operation time, blood loss, histological type, tumor size, vascular invasion, and central lymph node dissection). We performed univariate and multivariate analyses to examine risk factors for lymph node metastasis. We also examined risk factors for recurrence in 583 patients up to December 2017. Lymph node metastasis was observed in 100/801 patients (12.5%). Multivariate analysis of lymph node metastasis showed that patients with positive lymphatic invasion (odds ratio 2.57, 95% CI 1.62-4.04, P < .0001), positive venous invasion (odds ratio 2.31, 95% CI 1.48-3.61, P = .0002), and histologically poorly differentiated type (odds ratio 4.54, 95% CI 1.35-15.2, P = .014) were identified as risk factors. Postoperative recurrence was observed in 18/580 patients (3.1%). Risk factors for postoperative recurrence were also examined, including preoperative endoscopic treatment (odds ratio 3.59, 95% CI 1.18-10.9, P = .024), positive venous invasion (odds ratio 3.63, 95% CI 1.22-10.8, P = .021), positive lymph node metastasis (odds ratio 4.91, 95% CI 1.10-21.8, P = .037) were extracted as risk factors. In this study, venous invasion, lymphatic invasion, and histologically poorly differentiated type were identified as risk factors for lymph node metastasis in T1 colorectal cancer, and positive venous invasion, positive lymph node metastasis, and preoperative endoscopic treatment were identified as risk factors for recurrence. We hope that large prospective study will lead to the development of a more specific treatment strategy, including endoscopic treatment and additional surgical resection.

Transcriptomic and immunophenotypic profiling reveals molecular and immunological hallmarks of colorectal cancer tumourigenesis

ObjectiveBiological insights into the stepwise development and progression of colorectal cancer (CRC) are imperative to develop tailored approaches for early detection and optimal clinical management of this disease. Here, we...

Predicting lymph node metastasis and recurrence in patients with early stage colorectal cancer.

Tumor budding (TB), a powerful, independent predictor of colorectal cancer (CRC), is important for making appropriate treatment decisions. Currently, TB is assessed only using the tumor bud count (TBC). In this study, we aimed to develop a novel prediction model, which includes different TB features, for lymph node metastasis (LNM) and local recurrence in patients with pT1 CRC. Enrolled patients (n = 354) were stratified into training and validation cohorts. Independent predictors of LNM and recurrence were identified to generate predictive nomograms that were assessed using the area under the receiver operating characteristic (AUROC) and decision curve analysis (DCA). Seven LNM predictors [gross type, histological grade, lymphovascular invasion (LVI), stroma type, TBC, TB mitosis, and TB CDX2 expression] were identified in the training cohort. LNM, histology grade, LVI, TBC, stroma type, and TB mitosis were independent predictors of recurrence. We constructed an LNM predictive nomogram with a high clinical application value using the DCA. Additionally, a nomogram predicting recurrence-free survival (RFS) was constructed. It presented an AUROC value of 0.944 for the training cohort. These models may assist surgeons in making treatment decisions. In the high-risk group, radical surgery with a postoperative adjuvant chemotherapy was associated with RFS. Postoperative chemotherapy can be better for high-risk patients with pT1 CRC. We showed that TB features besides TBC play important roles in CRC pathogenesis, and our study provides prognostic information to guide the clinical management of patients with early stage CRC.

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

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). 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. 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). 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). 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.

HLA-G as a prognostic marker in stage II/III colorectal cancer: not quite there yet

Identifying innovative molecules involved in the tumor immune escape process could help refine the survival stratification of colorectal cancer (CRC) patients. HLA-G, a non-classical HLA molecule, physiologically involved in tolerogenic mechanisms, has recently emerged as a relevant prognostic marker in other tumor types, but ambiguous data are reported in the CRC setting. This study aims to evaluate the HLA-G expression and prognostic potential in a series of stage II/III CRCs. HLA-G expression was evaluated in 100 pT3 CRC cases by means of immunohistochemistry using the 4H84 and MEM-G/2 monoclonal antibodies. We observed heterogeneous expression of HLA-G showing different ranges: 4H84 expression ranged from > 1 to 40%—median 7%; MEM-G/2 expression ranged from 20 to 90%—median 50%. HLA-G positivity (any intensity > 1%) varied according to the antibody employed, identifying: 8 4H84 positive, 34 MEM-G/2 positive, 6 double-positive and 52 negative cases. Correlation with clinico-pathologic data showed a significant association with a poor tumor differentiation in stage III right-sided CRC subgroup (p = 0.043), while no other pathologic variable was significantly associated. Survival analysis revealed a reduced disease-free survival rate (HR 4.304613; p = 0.031) in the subgroup of CRC-related death cases, while no correlations were observed considering the whole series and the overall survival. In conclusion, HLA-G is a promising CRC prognostic marker however much work is still required regarding technical aspects and evaluation of expression.

PT3 colorectal cancer revisited: a multicentric study on the histological depth of invasion in more than 1000 pT3 carcinomas—proposal for a new pT3a/pT3b subclassification

BackgroundPathological TNM staging (pTNM) is the strongest prognosticator in colorectal carcinoma (CRC) and the foundation of its post-operative clinical management. Tumours that invade pericolic/perirectal adipose tissue generally fall into the pT3 category without further subdivision.MethodsThe histological depth of invasion into the pericolic/perirectal fat was digitally and conventionally measured in a training cohort of 950 CRCs (Munich). We biostatistically calculated the optimal cut-off to stratify pT3 CRCs into novel pT3a (≤3 mm)/pT3b (>3 mm) subgroups, which were then validated in two independent cohorts (447 CRCs, Bayreuth/542 CRCs, Mainz).ResultsCompared to pT3a tumours, pT3b CRCs showed significantly worse disease-specific survival, including in pN0 vs pN+ and colonic vs. rectal cancers (DSS: P < 0.001, respectively, pooled analysis of all cohorts). Furthermore, the pT3a/pT3b subclassification remained an independent predictor of survival in multivariate analyses (e.g. DSS: P < 0.001, hazard ratio: 4.41 for pT3b, pooled analysis of all cohorts). While pT2/pT3a CRCs showed similar survival characteristics, pT3b cancers remained a distinct subgroup with dismal survival.DiscussionThe delineation of pT3a/pT3b subcategories of CRC based on the histological depth of adipose tissue invasion adds valuable prognostic information to the current pT3 classification and implementation into current staging practices of CRC should be considered.

Differences in Factors Predicting Lymph Node Metastasis Between pT1 Rectal Cancer and pT1 Colon Cancer: A Retrospective Study.

Studies have demonstrated conflicting results regarding factors that predict lymph node metastasis (LNM) in pT1 colorectal cancers. We hypothesized that these discrepancies could be related to different factors predicting LNM between rectal and colon cancer. This study aimed to compare predicting factors for LNM between pT1 rectal and colon cancer. This retrospective study evaluated a prospectively maintained database that included 380 patients with pT1 colorectal cancer from January 2010 to December 2020. Patients were grouped according to whether they had rectal or colon cancer, with or without LNM, and factors predicting LNM were analyzed. In pT1 rectal cancer, LNM was associated with deeper submucosal (SM) invasion (P = .024) and a higher proportion of poorly differentiated tumors (P = .006). In pT1 colon cancer, LNM was associated with a higher proportion of moderately/poorly differentiated tumors (P = .002) and lymphatic invasion (P = .004). In the multivariate analysis for rectal cancer, depth of SM invasion (≥3000μm) was an independent predictive factor for LNM (95% confidence interval [CI], 1.48-27.94; P = .013), whereas for colon cancer, moderately/poorly differentiated tumors (95% CI, 1.38-8.13; P = .008) and lymphatic invasion (95% CI, 1.44-11.78; P = .008) were independent predictive factors for LNM. There were distinct differences in the factors predicting LNM between pT1 rectal cancer and colon cancer. These results suggest the necessity in differentiating between rectal and colon cancer when performing studies on LNM in pT1 colorectal cancer.

DENEB: Development of new criteria for curability after local excision of pathological T1 colorectal cancer using liquid biopsy.

According to the current international guidelines, high‐risk patients diagnosed with pathological T1 (pT1) colorectal cancer (CRC) who underwent complete local resection but may have risk of developing lymph node metastasis (LNM) are recommended additional intestinal resection with lymph node dissection. However, around 90% of the patients without LNM are exposed to the risk of being overtreated due to the insufficient pathological criteria for risk stratification of LNM. Circulating tumor DNA (ctDNA) is a noninvasive biomarker for molecular residual disease and relapse detection after treatments including surgical and endoscopic resection of solid tumors. The CIRCULATE‐Japan project includes a large‐scale patient‐screening registry of the GALAXY study to track ctDNA status of patients with stage II to IV or recurrent CRC that can be completely resected. Based on the CIRCULATE‐Japan platform, we launched DENEB, a new prospective study, within the GALAXY study for patients with pT1 CRC who underwent complete local resection and were scheduled for additional intestinal resection with lymph node dissection based on the standard pathologic risk stratification criteria for LNM. The aim of this study is to explore the ability of predicting LNM using ctDNA analysis compared with the standard pathological criteria. The ctDNA assay will build new evidence to establish a noninvasive personalized diagnosis in patients, which will facilitate tailored/optimal treatment strategies for CRC patients.

The Importance of Being "That" Colorectal pT1: A Combined Clinico-Pathological Predictive Score to Improve Nodal Risk Stratification.

The management of endoscopically resected pT1 colorectal cancer (CRC) relies on nodal metastasis risk estimation based on the assessment of specific histopathological features. Avoiding the overtreatment of metastasis-free patients represents a crucial unmet clinical need. By analyzing a consecutive series of 207 pT1 CRCs treated with colectomy and lymphadenectomy, this study aimed to develop a novel clinicopathological score to improve pT1 CRC metastasis prediction. First, we established the clinicopathological profile of metastatic cases: lymphovascular invasion (OR: 23.8; CI: 5.12–110.9) and high-grade tumor budding (OR: 5.21; CI: 1.60–16.8) correlated with an increased risk of nodal metastasis, while age at diagnosis >65 years (OR: 0.26; CI: 0.09–0.71) and high tumor-infiltrating lymphocytes (OR: 0.19; CI: 0.06–0.59) showed a protective effect. Combining these features, we built a five-tier risk score that, applied to our series, identified cases with a higher risk (score ≥ 2) of nodal metastasis (OR: 7.7; CI: 2.4–24.4). Notably, a score of 0 was only assigned to cases with no metastases (13/13 cases) and all the score 4 samples (2/2 cases) showed nodal metastases. In conclusion, we developed an effectively combined score to assess pT1 CRC nodal metastasis risk. We believe that its adoption within a multidisciplinary pT1 unit could improve patients' clinical management and limit surgical overtreatment.

Deep learning identifies inflamed fat as a risk factor for lymph node metastasis in early colorectal cancer.

The spread of early-stage (T1 and T2) adenocarcinomas to locoregional lymph nodes is a key event in disease progression of colorectal cancer (CRC). The cellular mechanisms behind this event are not completely understood and existing predictive biomarkers are imperfect. Here, we used an end-to-end deep learning algorithm to identify risk factors for lymph node metastasis (LNM) status in digitized histopathology slides of the primary CRC and its surrounding tissue. In two large population-based cohorts, we show that this system can predict the presence of more than one LNM in pT2 CRC patients with an area under the receiver operating curve (AUROC) of 0.733 (0.67-0.758) and patients with any LNM with an AUROC of 0.711 (0.597-0.797). Similarly, in pT1 CRC patients, the presence of more than one LNM or any LNM was predictable with an AUROC of 0.733 (0.644-0.778) and 0.567 (0.542-0.597), respectively. Based on these findings, we used the deep learning system to guide human pathology experts towards highly predictive regions for LNM in the whole slide images. This hybrid human observer and deep learning approach identified inflamed adipose tissue as the highest predictive feature for LNM presence. Our study is a first proof of concept that artificial intelligence (AI) systems may be able to discover potentially new biological mechanisms in cancer progression. Our deep learning algorithm is publicly available and can be used for biomarker discovery in any disease setting. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

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.

Tumor budding in colorectal cancer-Information for clinical use and instructions for practical evaluation

HintergrundBei einzelnen Patienten mit kolorektalen Karzinomen (CRC) zeigt sich ein schlechter klinischer Verlauf innerhalb desselben UICC-Stadiums (Union for International Cancer Control). Die Identifizierung von zusätzlichen Risikofaktoren ist daher notwendig, um eine optimale Therapieplanung zu erreichen.FragestellungIn welchen Situationen kann Tumor Budding die klinische Therapieentscheidung beeinflussen und wie sollte die standardisierte Auswertung erfolgen?Material und MethodeAktuelle Publikationen zum Thema Tumor Budding werden mit Fokus auf die praktische Anwendung und potenzielle Problemfälle in der Bestimmung des Tumor Buddings erläutert.ErgebnisseTumor Budding ist ein signifikanter Risikofaktor für einen schlechteren Verlauf des CRC und kann bei pT1-Karzinomen sowie Stadium-II-Karzinomen die Behandlung beeinflussen. Die Auswertung wurde durch die International Tumor Budding Consensus Conference (ITBCC) 2016 standardisiert und ist in der Praxis anwendbar. Schwierigkeiten in der Anwendung können durch die Kenntnis von potenziellen Problemfällen vermieden werden.