Tumor Budding and PDC Grade Are Stage Independent Predictors of Clinical Outcome in Mismatch Repair Deficient Colorectal Cancer

The prognostic significance of growth pattern, tumor budding, poorly differentiated clusters, desmoplastic reaction pattern and tumor-stroma ratio in colorectal cancer and an evaluation of their relationship with KRAS, NRAS, BRAF mutations

Growth pattern (GP), tumor budding (TB), poorly differentiated clusters (PDC), desmoplastic reaction pattern (DRP) and tumor-stroma ratio (TSR) are prognostic histomorphological parameters in colorectal cancer (CRC). Correlations between these parameters, their individual prognostic values, and their relationship with KRAS/NRAS/BRAF mutations have not been comprehensively examined. We aimed to investigate these associations, which have not been previously explored in this combination. 126 CRC cases were included. GP, TB, PDC, DRP and TSR were evaluated by two experienced pathologists. KRAS/NRAS/BRAF mutation profile were determined using qPCR. Demographic, clinicopathological and survival data were recorded. Interrelations were investigated by statistical analysis. Infiltrative GP was more frequent in high-score TB, PDC-G3, and stroma-high tumors (p < 0.05). High-score TB was more common in PDC-G3 and stroma-high tumors (p < 0.05). Immature DRP was more frequent in stroma-high tumors (p = 0.014). Among histomorphological parameters, a significant relationship was found only between infiltrative GP and the presence of KRAS mutation (p = 0.023). Moreover, GP was significantly associated with pT, lymphatic invasion, perineural invasion (p < 0.05). Effects on survival were assessed using Kaplan-Meier method and Cox proportional hazards model. TB and PDC were identified as independent predictors of overall survival. Higher TB score (p = 0.008) and higher PDC grade (p = 0.013) lead to worse survival. Interestingly, GP, DRP, TSR or KRAS/NRAS/BRAF mutations were not associated with overall survival. Our results highlight the prognostic significance of TB and PDC. We suggest incorporating TB and PDC into routine CRC reports. The association of KRAS mutation with infiltrative GP supports its role in the acquisition of invasive behavior.

Correlation Between Tumor Budding and Survivin Expression in Colorectal Cancer

Aim

Correlation of Survivin expression levels in tumor tissues and degree of tumor outgrowth with colorectal cancer characteristics.

Methods

The pathological tissues of 90 cases of colorectal cancer were observed by HE staining, and the tumor budding was judged by Ueno standard, and the expression of Survivin was detected by immunohistochemistry (IHC) technique (EnVision method), so as to analyze the correlation between tumor budding, the expression level of Survivin and the degree of tumor budding, and the correlation between the tumor budding and the patients' clinical characteristics.

Results

The expression level of Survivin was significantly correlated with TNM stage, lymph node metastasis and distant metastasis in patients with colorectal cancer; tumor outgrowth was significantly correlated with TNM stage, lymph node metastasis and distant metastasis in patients with colorectal cancer (P < 0.05); the expression level of Survivin was significantly correlated with the degree of tumor budding in patients with colorectal cancer (P < 0.05).

Conclusion

In this paper, we tested the relationship between Survivin and tumor budding in colon cancer, and analyzed its relationship with clinicopathological features, with a view to providing a reference for the mechanism related to colorectal cancer.

Tumor Budding Assessment in Colorectal Carcinoma: Normalization Revisited

Tumor budding (TB) is a powerful prognostic factor in colorectal cancer (CRC). An internationally standardized method for its assessment (International Tumor Budding Consensus Conference [ITBCC] method) has been adopted by most CRC pathology protocols. This method requires that TB counts are reported by field area (0.785 mm 2 ) rather than objective lens and a normalization factor is applied for this purpose. However, the validity of this approach is yet to be tested. We sought to validate the ITBCC method with a particular emphasis on normalization as a tool for standardization. In a cohort of 365 stage I-III CRC, both normalized and non-normalized TB were significantly associated with disease-specific survival and recurrence-free survival ( P <0.0001). Examining both 0.95 and 0.785 mm 2 field areas in a subset of patients (n=200), we found that normalization markedly overcorrects TB counts: Counts obtained in a 0.95 mm 2 hotspot field were reduced by an average of 17.5% following normalization compared with only 3.8% when counts were performed in an actual 0.785 mm 2 field. This resulted in 45 (11.3%) cases being downgraded using ITBCC grading criteria following normalization, compared with only 5 cases (1.3%, P =0.0007) downgraded when a true 0.785 mm 2 field was examined. In summary, the prognostic value of TB was retained regardless of whether TB counts in a 0.95 mm 2 field were normalized. Normalization resulted in overcorrecting TB counts with consequent downgrading of most borderline cases. This has implications for risk stratification and adjuvant treatment decisions, and suggests the need to re-evaluate the role of normalization in TB assessment.

Simultaneous analysis of tumor-infiltrating immune cells density, tumor budding status, and presence of lymphoid follicles in CRC tissue

Colorectal cancer (CRC) affects more than 1,000,000 people worldwide each year. Recently, the number of young patients with early-onset colorectal cancer has increased, and right-sided colorectal cancer is still often diagnosed only in advanced stages. The TNM classification is not perfect for CRC staging. This study aimed to perform, for the first time, simultaneous analysis of tumor-infiltrating immune cell density, presence of lymphoid follicles, and budding status in CRC tissue. Intraoperative samples of neoplastic tissue were collected from 195 consecutive patients who were admitted to the surgical ward for elective colorectal surgery. Histological parameters were assessed in the tissue samples: tumor budding foci, poorly differentiated clusters and areas of poorly differentiated components. Tumor-infiltrating immune cells (tumor-associated neutrophils and tumor-infiltrating lymphocytes) were detected in five randomly chosen, areas at the tumor center and at the invasive front. Additionally, the presence of lymphoid follicles in CRC tissue was assessed. Tumor budding parameters were positively correlated with colorectal cancer advancement or histologic (mucinous) type of CRC. The number of poorly differentiated clusters was higher in younger patients. Lower densities of CD3 and CD4 lymphocytes were seen in CRC with a greater depth of tumor invasion. Lower densities of CD3 and CD8 lymphocytes were found in CRC with metastases to the surrounding lymph nodes. The lower density of CD8 lymphocytes was observed in CRC with distant metastases. Lower densities of tumor-associated neutrophils and tumor-infiltrating lymphocytes (CD3 and CD8) were revealed in CRC without lymphoid follicles. The number of lymphoid follicles was higher in patients with less advanced CRCs. Three histopathology markers, such as high tumor budding, scanty lymphocyte infiltration, and the poverty of lymphoid follicles, complement each other, appear to be reliable indicators of colorectal cancer progression, and could be useful in everyday medical practice, but their widespread use requires further research. We propose to take into account these markers, in the assessment of colorectal cancer advancement, in addition to the TNM classification.

Tumor budding as an indicator for lymph node metastasis and prognosis of early gastric cancer

BACKGROUND

Tumor budding, considered as an independent risk factor reflecting prognosis of some malignant tumors, has been recognized as an important clinicopathological indicator of colorectal carcinoma. However, the evaluation of tumor budding and its clinicopathological significance in gastric cancer remain controversial.

AIM

To investigate the relationship between tumor budding and clinical biological behavior of early gastric cancer (EGC) and assess the predictive value of tumor budding for lymph node metastasis as well as its impact on prognosis of EGC patients.

METHODS

Tissue specimens of 164 EGC patients who underwent radical gastrectomy between June 2011 and January 2017 from a single center were selected to carry out HE and CK staining respectively, so as to evaluate tumor budding under light microscopy. Clinicopathological data and follow-up results of all EGC patients were collected for statistical analysis among tumor budding, EGC clinicopathological factors and prognosis.

RESULTS

Of all 164 EGC patients, there were 84 (51.2%) cases with mucosal invasion and 80 (48.8%) cases with submucosal invasion. Meanwhile, 32 cases (19.5%) had lymph node metastasis, 19 (11.6%) had lympho-vascular invasion and 4 (2.4%) had early recurrence. Tumor budding were observed in 90 (54.9%) patients, with low-grade budding 68 (41.5%) cases and high-grade budding 22 (13.4%) cases. Tumor budding was closely correlated with tumor size (c² = 6.609, P = 0.037), tumor histologic differentiation (c² = 10.522, P = 0.032), depth of invasion (c² = 8.787, P = 0.012), lymph node metastasis (c² = 24.226, P < 0.01), TNM stage (c² = 24.226, P < 0.01), lympho-vascular invasion (c² = 8.225, P = 0.016) and early recurrence (c² = 6.462, P = 0.040). Additionally, tumor budding was correlated with postoperative survival rate as well. Multiple regression analysis revealed that tumor budding was an independent influencing factor of postoperative 3-year survival rate, 5-year survival rate, OS, DFS and DSS (P < 0.05). Furthermore, tumor budding was an independent risk factor of lymph node metastasis of EGC patients, and high-grade budding was a high-risk indicator of lymph node metastasis.

CONCLUSION

Tumor budding is related to tumor size, tumor histologic differentiation, depth of invasion, lymph node metastasis, lympho-vascular invasion and early recurrence of EGC. Tumor budding, especially high-grade budding can serve as an indicator for predicting lymph node metastasis of EGC, and high-grade budding could be an important parameter for evaluating prognosis of EGC patients.

Prognostic Ability of Tumor Budding Outperforms Poorly Differentiated Clusters in Gastric Cancer

The prognostic value of histological phenomena tumor budding (TB) and poorly differentiated clusters (PDCs) have been less studied in gastric cancer (GAC) and the data provided so far are controversial. In our study, 290 surgically resected GAC cases were evaluated for TB according to the criteria of International Tumor Budding Consensus Conference (ITBCC) and PDC, and both parameters were scored on a three-grade scale as described for colorectal cancer previously (0: Grade0, 1-4: Grade1, 5-9: Grade2 and ≥10: Grade3) and classified as low (Grade0-2) and high (Grade3) TB/PDC. High TB/PDC was associated with diffuse-type morphology, higher pT status, incomplete surgical resection, poor tumor differentiation and perineural and lymphovascular invasion. Multivariable survival analyses have shown an independent prognostic role of high TB with poorer overall survival in the total cohort (p = 0.014) and in intestinal-type adenocarcinomas (p = 0.005). Multivariable model revealed high TB as an independent predictor for lymph node metastasis in both the total cohort (p = 0.019) and in the intestinal type adenocarcinomas (p = 0.038). In contrast to tumor budding, no significant association was found between PDC and the occurrence of lymph node metastasis and tumor stage and even survival. In conclusion, tumor budding is an independent prognostic factor of survival in gastric cancer, especially in intestinal-type adenocarcinomas.

Role of one-step nucleic acid amplification in colorectal cancer lymph node metastases detection

Current histopathological staging procedures in colorectal cancer (CRC) depend on midline division of the lymph nodes (LNs) with one section of hematoxylin and eosin staining. Cancer cells outside this transection line may be missed, which could lead to understaging of Union for International Cancer Control Stage II high-risk patients. The one-step nucleic acid amplification (OSNA) assay has emerged as a rapid molecular diagnostic tool for LN metastases detection. It is a molecular technique that can analyze the entire LN tissue using a reverse-transcriptase loop-mediated isothermal amplification reaction to detect tumor-specific cytokeratin 19 mRNA. Our findings suggest that the OSNA assay has a high diagnostic accuracy in detecting metastatic LNs in CRC and a high negative predictive value. OSNA is a standardized, observer-independent technique, which may lead to more accurate staging. It has been suggested that in stage II CRC, the upstaging can reach 25% and these patients can access postoperative adjuvant chemotherapy. Moreover, intraoperative OSNA sentinel node evaluation may allow early CRC to be treated with organ-preserving surgery, while in more advanced-stage disease, a tailored lymphadenectomy can be performed considering the presence of aberrant lymphatic drainage and skip metastases.

Impact of microsatellite status in early-onset colonic cancer

BACKGROUND

The molecular profile of early-onset colonic cancer is undefined. This study evaluated clinicopathological features and oncological outcomes of young patients with colonic cancer according to microsatellite status.

METHODS

Anonymized data from an international collaboration were analysed. Criteria for inclusion were patients younger than 50 years diagnosed with stage I-III colonic cancer that was surgically resected. Clinicopathological features, microsatellite status, and disease-specific outcomes were evaluated.

RESULTS

A total of 650 patients fulfilled the criteria for inclusion. Microsatellite instability (MSI) was identified in 170 (26.2 per cent), whereas 480 had microsatellite-stable (MSS) tumours (relative risk of MSI 2.5 compared with older patients). MSI was associated with a family history of colorectal cancer and lesions in the proximal colon. The proportions with pathological node-positive disease (45.9 versus 45.6 per cent; P = 1.000) and tumour budding (20.3 versus 20.5 per cent; P = 1.000) were similar in the two groups. Patients with MSI tumours were more likely to have BRAF (22.5 versus 6.9 per cent; P < 0.001) and KRAS (40.0 versus 24.2 per cent; P = 0.006) mutations, and a hereditary cancer syndrome (30.0 versus 5.0 per cent; P < 0.001; relative risk 6). Five-year disease-free survival rates in the MSI group were 95.0, 92.0, and 80.0 per cent for patients with stage I, II, and III tumours, compared with 88.0, 88.0, and 65.0 per cent in the MSS group (P = 0.753, P = 0.487, and P = 0.105 respectively).

CONCLUSION

Patients with early-onset colonic cancer have a high risk of MSI and defined genetic conditions. Those with MSI tumours have more adverse pathology (budding, KRAS/BRAF mutations, and nodal metastases) than older patients with MSI cancers.

A Novel Combined Tumor Budding-Poorly Differentiated Clusters Grading System Predicts Recurrence and Survival in Stage I-III Colorectal Cancer

Tumor budding (TB) and poorly differentiated clusters (PDCs) are powerful prognostic factors in colorectal cancer (CRC). Despite their morphologic and biological overlap, TB and PDC are assessed separately and are distinguished by an arbitrary cutoff for cell cluster size. This cutoff can be challenging to apply in practice and its biological significance remains unclear. We developed a novel scoring system that incorporates TB and PDC into a single parameter ("Combined Score"; CS), eliminating the need for such cutoffs and allowing the prognostic value of PDC to be captured alongside TB. In a cohort of 481 stage I-III CRC resections, CS was significantly associated with American Joint Committee on Cancer (AJCC) stage, T-stage, N-stage, histologic grade, tumor deposits, lymphovascular invasion, and perineural invasion (P<0.0001). In addition, CS was significantly associated with decreased 5-year recurrence-free survival, overall survival, and disease-specific survival (P<0.0001). TB and PDC showed similar associations with oncologic outcomes, with hazard ratios consistently lower than for CS. The association between CS and oncologic outcomes remained significant in subgroup analyses stratified by AJCC stage, anatomic location (rectum/colon) and neoadjuvant therapy status. On multivariable analysis, CS retained its significant association with oncologic outcomes (P=0.0002, 0.005, and 0.009) for recurrence-free survival, disease-specific survival, and overall survival, respectively. In conclusion, CS provides powerful risk stratification in CRC which is at least equivalent to that of TB and PDC assessed individually. If validated elsewhere, CS has practical advantages and a biological rationale that may make it an attractive alternative to assessing these features separately.

Automatic Tumor Grading on Colorectal Cancer Whole-Slide Images: Semi-Quantitative Gland Formation Percentage and New Indicator Exploration

Tumor grading is an essential factor for cancer staging and survival prognostication. The widely used the WHO grading system defines the histological grade of CRC adenocarcinoma based on the density of glandular formation on whole-slide images (WSIs). We developed a fully automated approach for stratifying colorectal cancer (CRC) patients' risk of mortality directly from histology WSI relating to gland formation. A tissue classifier was trained to categorize regions on WSI as glands, stroma, immune cells, background, and other tissues. A gland formation classifier was trained on expert annotations to categorize regions as different degrees of tumor gland formation versus normal tissues. The glandular formation density can thus be estimated using the aforementioned tissue categorization and gland formation information. This estimation was called a semi-quantitative gland formation ratio (SGFR), which was used as a prognostic factor in survival analysis. We evaluated gland formation percentage and validated it by comparing it against the WHO cutoff point. Survival data and gland formation maps were then used to train a spatial pyramid pooling survival network (SPPSN) as a deep survival model. We compared the survival prediction performance of estimated gland formation percentage and the SPPSN deep survival grade and found that the deep survival grade had improved discrimination. A univariable Cox model for survival yielded moderate discrimination with SGFR (c-index 0.62) and deep survival grade (c-index 0.64) in an independent institutional test set. Deep survival grade also showed better discrimination performance in multivariable Cox regression. The deep survival grade significantly increased the c-index of the baseline Cox model in both validation set and external test set, but the inclusion of SGFR can only improve the Cox model less in external test and is unable to improve the Cox model in the validation set.

Computer-extracted features of nuclear morphology in hematoxylin and eosin images distinguish stage II and IV colon tumors

We assessed the utility of quantitative features of colon cancer nuclei, extracted from digitized hematoxylin and eosin-stained whole slide images (WSIs), to distinguish between stage II and stage IV colon cancers. Our discovery cohort comprised 100 stage II and stage IV colon cancer cases sourced from the University Hospitals Cleveland Medical Center (UHCMC). We performed initial (independent) model validation on 51 (143) stage II and 79 (54) stage IV colon cancer cases from UHCMC (The Cancer Genome Atlas's Colon Adenocarcinoma, TCGA-COAD, cohort). Our approach comprised the following steps: (1) a fully convolutional deep neural network with VGG-18 architecture was trained to locate cancer on WSIs; (2) another deep-learning model based on Mask-RCNN with Resnet-50 architecture was used to segment all nuclei from within the identified cancer region; (3) a total of 26 641 quantitative morphometric features pertaining to nuclear shape, size, and texture were extracted from within and outside tumor nuclei; (4) a random forest classifier was trained to distinguish between stage II and stage IV colon cancers using the five most discriminatory features selected by the Wilcoxon rank-sum test. Our trained classifier using these top five features yielded an AUC of 0.81 and 0.78, respectively, on the held-out cases in the UHCMC and TCGA validation sets. For 197 TCGA-COAD cases, the Cox proportional hazards model yielded a hazard ratio of 2.20 (95% CI 1.24-3.88) with a concordance index of 0.71, using only the top five features for risk stratification of overall survival. The Kaplan-Meier estimate also showed statistically significant separation between the low-risk and high-risk patients, with a log-rank P value of 0.0097. Finally, unsupervised clustering of the top five features revealed that stage IV colon cancers with peritoneal spread were morphologically more similar to stage II colon cancers with no long-term metastases than to stage IV colon cancers with hematogenous spread. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

MicroRNA Expression Profiling Predicts Nodal Status and Disease Recurrence in Patients Treated with Curative Intent for Colorectal Cancer

Background: Approximately one-third of colorectal cancer (CRC) patients will suffer recurrence. MiRNAs are small non-coding RNAs that play important roles in gene expression. We aimed to correlate miRNA expression with aggressive clinicopathological characteristics and survival outcomes in CRC. Methods: Tumour samples were extracted from 74 CRC patients. MiRNAs were quantified using real-time reverse transcriptase polymerase chain reaction. Descriptive statistics and Cox regression analyses were performed to correlate miRNA targets with clinicopathological and outcome data. Results: Aberrant miR-21 and miR-135b expression correlate with increased nodal stage (p = 0.039, p = 0.022). Using univariable Cox regression analyses, reduced miR-135b (β-coefficient −1.126, hazard ratio 0.324, standard error (SE) 0.4698, p = 0.017) and increased miR-195 (β-coefficient 1.442, hazard ratio 4.229, SE 0.446, p = 0.001) predicted time to disease recurrence. Survival regression trees analysis illustrated a relative cut-off of ≤0.488 for miR-195 and a relative cut-off of >−0.218 for miR-135b; both were associated with improved disease recurrence (p < 0.001, p = 0.015). Using multivariable analysis with all targets as predictors, miR-195 (β-coefficient 3.187, SE 1.419, p = 0.025) was the sole significant independent predictor of recurrence. Conclusion: MiR-195 has strong value in predicting time to recurrence in CRC patients. Additionally, miR-21 and miR-135b predict the degree nodal burden. Future studies may include these findings to personalize therapeutic and surgical decision making.

Prognostic and Predictive Value of Tumor Budding in Colorectal Cancer

BACKGROUND

Tumor budding (TB) is an adverse prognostic factor in colorectal cancer (CRC). International consensus on a standardized assessment method has led to its wider reporting. However, uncertainty regarding its clinical value persists. This study aimed to (1) confirm the prognostic significance of TB, particularly in stage II CRC; (2) to determine optimum thresholds for TB risk grouping; and (3) to determine whether TB influences responsiveness to chemotherapy.

METHODS

TB was assessed in CRC sections from 1575 QUASAR trial patients randomized between adjuvant chemotherapy and observation. Optimal risk group cutoffs were determined by maximum likelihood methods, with their influence on recurrence and mortality investigated in stratified log-rank analyses on exploratory (n = 504), hypothesis-testing (n = 478), and final (n = 593) data sets.

RESULTS

The optimal threshold for high-grade TB (HGTB) was ≥ 10 buds per 1.23 mm². High-grade TB tumors had significantly worse outcomes than those with lower TB: 10-year recurrence 36% versus 22% (risk ratio, 2.00 [95% CI, 1.62-2.45]; 2P < .0001) and 10-year mortality 50% vs. 37% (risk ratio, 1.53 [95% CI, 1.34-1.76]; 2P < .0001). The prognostic significance remained equally strong after allowance for other pathological risk factors, including stage, grade, lymphovascular invasion, and mismatch repair status. There was a nonsignificant trend toward increasing chemotherapy efficacy with increasing bud counts.

CONCLUSIONS

TB is a strong independent predictor of recurrence. Chemotherapy efficacy is comparable in patients with higher and lower TB; hence, absolute reductions in recurrence and death with chemotherapy should be about twice as large in patients with ≥ 10 than < 10 TB counts.

Morphology Matters: A Critical Reappraisal of the Clinical Relevance of Morphologic Criteria From the 2019 WHO Classification in a Large Colorectal Cancer Cohort Comprising 1004 Cases

The 2019 World Health Organization (WHO) classification of colorectal carcinoma (CRC) profoundly reclassified CRC subtypes and introduces tumor budding as a second major grading criterion, while condensing conventional grade into a 2-tiered system. So far it remains largely unexplored how these parameters interact with each other and whether they truly have an independent impact on patient prognosis. We reclassified a large single-center cohort of 1004 CRCs spanning 2 decades for adjusted WHO grade (low vs. high), tumor budding (Bd1/Bd2/Bd3), and CRC subtype (adenocarcinoma not otherwise specified, micropapillary, mucinous, serrated, medullary, adenoma-like, signet-ring cell, mixed adenoneuroendocrine carcinoma/neuroendocrine carcinoma, undifferentiated) according to the criteria of the 2019 WHO classification. We investigated the interaction of these parameters, their connection to stage/microsatellite status, and their significance for patient survival in the different subgroups. Specific subtypes other than adenocarcinoma not otherwise specified represented one third of all CRCs and were unevenly distributed throughout stage and microsatellite subgroups. Subtypes, WHO grade and tumor budding profoundly impacted all survival parameters (P<0.001 for all analyses), with CRC subtypes and tumor budding-but not WHO grade-being stage-independent prognosticators for all survival comparisons. WHO grade had very limited prognostic value in CRC subtypes, while tumor budding retained its strong prognostic impact in most scenarios. Accurate delineation of CRC subtypes introduced in the 2019 WHO classification provides strong stage-independent prognostic information, arguing that they should be considered in pathology reports and in clinical trials. Of the morphology-based grading schemes included in the 2019 WHO, tumor budding outperforms WHO grade.

Association Between Obesity and Histological Tumor Budding in Patients With Nonmetastatic Colon Cancer

IMPORTANCE

Obesity is associated with increased risk of colorectal cancer (CRC) and a more aggressive disease course. Tumor budding (TB) is an important prognostic factor for CRC, but its association with obesity is unknown.

OBJECTIVE

To evaluate the association of TB with obesity and other prognostic factors in colon cancer.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study involved a histological review of colon cancer specimens obtained during 7 years (January 2008 to December 2015) at the University of Kentucky Medical Center; data analysis was conducted from February 2020 to January 2021. Specimens came from 200 patients with stage I to III colon cancer; patients with stage 0, stage IV, or incomplete data were excluded.

MAIN OUTCOMES AND MEASURES

TB was defined as 1 to 4 malignant cells at the invasive edge of the tumor, independently assessed by 2 academic pathologists. The primary outcome was the association of TB with obesity (defined as body mass index [BMI] of 30 or greater). Secondary outcomes include the association of TB with clinical features (ie, age, race, sex, TNM stage, tumor location) and pathological features (ie, poorly differentiated tumor clusters [PDCs], Klintrup-Mäkinen inflammatory score, desmoplasia, infiltrative tumor border, tumor necrosis, and tumor-to-stroma ratio).

RESULTS

A total of 200 specimens were reviewed. The median (interquartile range) age of patients was 62 (55-72) years, 102 (51.0%) were women, and the mean (SD) BMI was 28.5 (8.4). A total of 57 specimens (28.5%) were from stage I tumors; 74 (37.0%), stage II; and 69 (34.5%), stage III. Of these, 97 (48.5%) had low-grade (<5 buds), 36 (18.0%) had intermediate-grade (5-9 buds), and 67 (33.5%) had high-grade (≥10 buds) TB. Multivariable analysis adjusting for clinical and histological factors demonstrated that higher TB grade was associated with obesity (odds ratio [OR], 4.25; 95% CI, 1.95-9.26), higher PDC grade (grade 2 vs 1: OR, 9.14; 95% CI, 3.49-23.93; grade 3 vs 1: OR, 5.10; 95% CI, 2.30-11.27), increased infiltrative tumor border (OR, 1.03; 95% CI, 1.01-1.04), cecal location (OR, 2.55; 95% CI, 1.09-5.97), and higher stage (eg, stage III vs stage I for high-grade or intermediate-grade vs low-grade TB: OR, 2.91; 95% CI, 1.00-8.49). Additionally, patients with a higher TB grade had worse overall survival (intermediate vs low TB: hazard ratio, 2.20; 95% CI, 1.11-4.35; log-rank P = .02; high vs low TB: hazard ratio, 2.67; 95% CI, 1.45-4.90; log-rank P < .001).

CONCLUSIONS AND RELEVANCE

In this cohort study, a novel association between high TB grade and obesity was found. The association could reflect a systemic condition (ie, obesity) locally influencing aggressive growth (ie, high TB) in colon cancer.

Lymph Node Tumor Burden Correlates With Tumor Budding and Poorly Differentiated Clusters: A New Prognostic Factor in Colorectal Carcinoma?

INTRODUCTION

Molecular lymph node (LN) staging in early colorectal cancer (CRC) has demonstrated to be more precise than conventional histopathology pN staging. Tumor budding (TB) and poorly differentiated clusters (PDCs) are associated with LN metastases, recurrences, and lower survival in CRC. We evaluated the correlation between the total tumor load (TTL) in LNs from CRC surgical specimens with patient outcome, TB, and PDC.

METHODS

In this retrospective multicentre study, 5,931 LNs from 342 stage I-III CRC were analyzed by both hematoxylin and eosin and molecular detection of tumor cytokeratin 19 mRNA by one-step nucleic acid amplification. TB and PDC were evaluated by hematoxylin and eosin and cytokeratin 19 immunohistochemistry.

RESULTS

One-step nucleic acid was positive in 38.3% patients (n = 131). Tumor Budding was low in 45% cases, intermediate in 25%, and high in 30%. Poorly Differentiated Clusters were low-grade G1 in 53%, G2 in 32%, and G3 in 15%. TB and PDC correlated with TTL, high-grade, lymphovascular and perineural invasion, pT, pN and stage (P < 0.001). TB, PDC, and TTL ≥ 6,000 copies/µL were associated with worse overall survival (P = 0.002, P = 0.013, and P = 0.046) and disease-free survival (P < 0.001).

DISCUSSION

The implementation of more sensitive molecular methods to assess LN status is a promising alternative approach to pN staging, which could be integrated to other factors to help risk stratification and management of patients with early-stage CRC. This study demonstrates the correlation of the amount of LN tumor burden with TB and PDCs. TTL is related to the outcome and could be used as a new prognostic factor in CRC (see Visual Abstract, Supplementary Digital Content 2, http://links.lww.com/CTG/A512).

Clinical Significance of Preoperative Inflammatory Markers in Prediction of Prognosis in Node-Negative Colon Cancer: Correlation between Neutrophil-to-Lymphocyte Ratio and Poorly Differentiated Clusters

Although stage I and II colon cancers (CC) generally show a very good prognosis, a small proportion of these patients dies from recurrent disease. The identification of high-risk patients, who may benefit from adjuvant chemotherapy, becomes therefore essential. We retrospectively evaluated 107 cases of stage I (n = 28, 26.2%) and II (n = 79, 73.8%) CC for correlations among preoperative inflammatory markers, histopathological factors and long-term prognosis. A neutrophil-to-lymphocyte ratio greater than 3 (H-NLR) and a platelet-to-lymphocyte ratio greater than 150 (H-PLR) were significantly associated with the presence of poorly differentiated clusters (PDC) (p = 0.007 and p = 0.039, respectively). In addition, H-NLR and PDC proved to be significant and independent survival prognosticators for overall survival (OS; p = 0.007 and p < 0.001, respectively), while PDC was the only significant prognostic factor for cancer-specific survival (CSS; p < 0.001,). Finally, the combination of H-NLR and PDC allowed an optimal stratification of OS and CSS in our cohort, suggesting a potential role in clinical practice for the identification of high-risk patients with stage I and II CC.

Development and validation of MMR prediction model based on simplified clinicopathological features and serum tumour markers

BACKGROUND

Although simplified clinicopathological features and serum tumour markers (STMs) were reported to be associated with the status of mismatch repair (MMR) in colorectal cancer (CRC) patients, their predictive value alone or in combination for MMR status remains unknown.

METHODS

A retrospective analysis of 3274 participants with MMR testing and STMs measurements from two institutions was conducted. The prediction model was developed in the primary cohort that consisted of 1964 participants. Best subset regression was applied to select the most useful predictors from the primary dataset. The performance of the nomogram was evaluated with respect to its calibration, discrimination, and clinical usefulness. External validation was performed in an independent validation cohort of 1310 consecutive CRC patients.

FINDINGS

Among the ten simplified clinicopathological features, seven variables were selected as the best subset of risk factors to develop pathology-based model, including age, tumour diameters, histology, tumour location, perineural invasion, the number of sampled lymph nodes (LNs) and positive LNs. The model showed good calibration and discrimination, with an AUC of 0.756 (95% CI, 0.722 to 0.789) in the primary cohort and 0.754 (95% CI, 0.715 to 0.793) in the validation cohort. After the addition of CEA and CA 72-4, the performance of pathology-based model was significantly improved in in both the primary cohort (AUC: 0.805 (0.774-0.835) vs. 0.756 (0.722-0.789), P < 0.001) and validation cohort (AUC: 0.796 (0.758-0.835) vs. 0.754 (0.715-0.793), P < 0.001). The results of decision curve analysis revealed that using our models to predict the status of MMR would add more benefit than either the detect-all-patients scheme or the detect-none scheme.

INTERPRETATION

The models based on simplified clinicopathological features alone or in combination with STMs can be conveniently used to facilitate the postoperative individualized prediction of MMR status in CRC patients.

Prognostic impact of tumor budding and EMT in periampullary adenocarcinoma: a quantitative approach

The presence of invasive cell clusters known as tumor budding and the closely related epithelial mesenchymal transition (EMT) have a prognostic impact on cancer patients' overall survival. Interestingly, data quantitatively analyzing and correlating the amount of tumor buds and patient overall survival as well as the impact of expression of epithelial phenotype markers are missing. Periampullary carcinoma samples of 171 patients were immunohistochemically stained for E-Cadherin (ECad). Tumor cell clusters (TCC, defined from one to 50 cells) were manually quantified comprising tumor cell number and subcellular localization of ECad expression (membranous, cytoplasmic or mixed). Data analyses were performed using elastic net feature selection. Hereby, five distinct intervals of TCC sizes and corresponding fractions of cells with distinct ECad expression were identified. Prognostic features of the defined budding categories were entered into a subsequent Cox regression model together with standard clinicopathological parameters and, based on the model prediction, cases were categorized into "low and high budding" grades. Overall median TCC size was 16 cells (range: 2-36 cells). The median number of TCCs per tumor was 42 (range: 3-283). Elastic net feature selection identified TCCs of 6-10 and 31-35 cells as prognostically most relevant negative and positive features, respectively. Regarding ECad expression, cytoplasmic ECad expression in TCCs of 11-15 as well as of 26-30 cells revealed prognostic relevance. Combining TCC numbers and ECad expression, budding grade qualified as independent prognostic factor for patient overall survival (p<0.001) in a multivariable clinicopathologic Cox model. Applying an advanced modelling by machine learning on a cohort of periampullary cancers, we show that not the smallest TCCs (1-5 cells) but tumor cell nests containing 6-10 cells display the strongest negative prognostic relevance. Moreover, we demonstrate that larger TCCs might have a strong positive prognostic impact in periampullary adenocarcinomas, contributing to establishing an advanced grading system.

Intraepithelial tumour infiltrating lymphocytes are associated with absence of tumour budding and immature/myxoid desmoplastic reaction, and with better recurrence-free survival in stages I-III colorectal cancer

AIMS

Tumour budding (TB), desmoplastic reaction (DR) and intraepithelial tumour infiltrating lymphocytes (iTILs) are recently recognised prognostic factors in colorectal cancer (CRC). In this study, we evaluated their significance and relationship to each other and their cumulative effect on survival.

METHODS AND RESULTS

A total of 372 stages I-III CRC cases from 2013 to 2016 were included. Low TB was identified in 302 (81%) cases, immature/myxoid DR in 67 (18%) cases and iTILs in 130 (35.0%) cases. iTILs was associated with low budding (P = 0.0247), non-myxoid DR (P = 0.0004), poorly differentiated histology (P = 0.0015), absence of perineural invasion (P = 0.0367) and loss of mismatch repair proteins (P = 0.0002). Absence of iTILs and presence of immature/myxoid DR were associated with a worse recurrence-free survival (RFS) [hazard ratio (HR) = 2.191, 95% confidence interval (CI) = 1.232-3.895; and HR = 5.706, 95% CI = 3.632-8.964, respectively]. A competing risk analysis showed statistically significant prognostic groups combining iTILs and TB (P < 0.0001). Cases with iTILs and low TB were associated with better RFS compared to cases without iTILs and with intermediate/high TB (HR = 0.214, 95% CI = 0.109-0.421). Similarly, combining iTILs and DR revealed statistically significant prognostic groups (P < 0.0001). Cases with iTILs and a non-myxoid DR had better RFS compared to cases without iTILs and immature/myxoid DR (HR = 0.113, 95% CI = 0.056-0.230). On multivariate cause-specific analysis, patients' age (P = 0.0045), iTILs (P = 0.0345), DR (P < 0.0001) and pTNM prognostic groups (P < 0.0001) were associated with RFS.

CONCLUSIONS

Our study validates the association of iTILs and DR as independent prognostic finding in CRC, and propose a prognostic model using the combinations of iTILs with TB and stromal reaction in CRC.

Poorly differentiated clusters in colorectal cancer: a current review and implications for future practice

Poorly differentiated clusters (PDC), defined as small groups of ≥5 tumour cells without glandular differentiation, have gained recent attention as a promising prognostic factor in colorectal cancer (CRC). Numerous studies have shown PDC to be significantly associated with other adverse histopathological features and worse clinical outcomes. PDC may hold particular promise in stage II colon cancer, where risk stratification plays a critical role in patient selection for adjuvant chemotherapy. In addition, emerging evidence suggests that PDC can predict lymph node metastasis in endoscopically resected pT1 CRC, potentially helping the selection of patients for oncological resection. In 'head-to-head' comparisons, PDC grade has consistently outperformed conventional histological grading systems both in terms of risk stratification and reproducibility. With a number of large-scale studies now available, this review evaluates the evidence regarding the prognostic significance of PDC, considers its relationship with other emerging invasive front prognostic markers (such as tumour budding and stroma type), assesses its 'practice readiness', addressing issues such as interobserver reproducibility, scoring methodologies and special histological subtypes (e.g. micropapillary and mucinous carcinoma), and draws attention to ongoing challenges and areas in need of further study. Finally, emerging data on the role of PDC in non-colorectal cancers are briefly considered.

Histology of Colorectal Carcinoma: Proven and Purported Prognostic Factors

Although tumor stage has a profound influence on prognosis, several histologic features are also important. These parameters predict biological behavior and can be used by clinicians to determine whether patients are at high risk for disease progression and, thus, are candidates for adjuvant therapy, particularly when they have localized (ie, stage II) disease. This article summarizes the evidence supporting the prognostic values of various histologic parameters evaluated by pathologists who assign pathologic stage to colorectal cancers. Criteria to be discussed include histologic subtype, tumor grade, lymphatic and perineural invasion, tumor budding, and host immune responses.

The presence of poorly differentiated clusters predicts survival in stage II colorectal cancer

In stage II colorectal carcinoma (CRC), adjuvant chemotherapy is reserved to cases at high risk of adverse outcome. This study aims to investigate the prognostic value of tumor budding (TB) and poorly differentiated clusters (PDC) in this setting. In a cohort of 149 patients with surgically resected stage II CRC not undergoing neoadjuvant or adjuvant treatments, we assessed the prognostic value of several clinical-pathological variables, including PDC and TB, on cancer-specific survival (CSS). Rectal location, lymphovascular invasion, and a number of lymph nodes < 12 confirmed to be significant and independent predictors of shorter CSS. A total of 117 CRCs were graded as PDC-G1 (0-4 PDCs), 19 as PDC-G2 (5-9 PDCs), and 13 as PDC-G3 (> 9 PDCs). Ninety-eight cases had PDC absent. TB foci were found in 91 CRCs; 121 were classified Bd1, 16 were Bd2, and 12 were Bd3. PDC-G2/G3 was significantly prognostic of shorter CSS (P < 0.0001). Among PDC-G1 cases, the presence of PDC was significantly associated with reduced CSS (P < 0.0001). Moreover, in the whole 149 CRCs, it had higher sensitivity and specificity to identify high-risk patients, compared to PDC grade, and it was independently associated with shorter CSS at multivariate analysis. High TB grade (Bd3) was significantly associated with shorter CSS (P = 0.0001), but it lost prognostic value at multivariate analysis. These findings suggest that the presence of PDC in stage II CRCs might be added to the pool of high-risk factors, warranting the use of adjuvant chemotherapy.

Clinicopathologic determinants of pathologic treatment response in neoadjuvant treated rectal adenocarcinoma

Neoadjuvant treatment (NAT) followed by total mesorectal excision is currently considered the standard of treatment for rectal adenocarcinoma. The degree of pathologic treatment response (pTR) correlates significantly with the recurrence free survival and overall survival (OS). However, it remains unclear which clinical and pathologic factors are associated with a more robust response to NAT, including showing pathologic complete response (pCR). Chemokine receptor 4 (CXCR4) overexpression has been associated with unfavorable OS in some studies. In this study, we sought to evaluate the clinicopathologic determinants of pTR in neoadjuvant treated rectal adenocarcinoma (NAT-RA). We retrospectively identified 91 patients who underwent pre-treatment diagnostic biopsy, NAT, and surgical resection at our institution. The archival slides were reviewed for pathologic features in the pre-treatment biopsies and for assessment of pTR in the resection specimens according to the current College of American Pathologist (CAP)'s guidelines. pCR was obtained in 16.5% of the cases, whereas 20.9% had near pCR, 30.8% had partial response, and 31.9% had a poor/no response. CXCR4 immunohistochemical analysis was also performed on the pre-treatment biopsies. Lower pre-treatment cT-stage (p = 0.019) and pre-treatment AJCC cTNM stage groups (p = 0.004), longer time interval between completion of NAT and resection (p = 0.022), and presence of tumor-infiltrating lymphocytes in the pre-treatment biopsies (p = 0.019) were significantly associated with a better pTR. CXCR4 nuclear expression was associated with a lower percentage of residual tumor (p = 0.036). Pre-treatment CEA levels, tumor differentiation, CAP treatment response groups and lower percentage of residual tumor were associated with a better OS.

Significance of neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, lymphocyte-to-monocyte ratio and prognostic nutritional index for predicting clinical outcomes in T1-2 rectal cancer

Background

Inflammation-related parameters have been revealed to have prognostic value in multiple caners. However, the significance of some inflammation-related parameters, including the peripheral blood neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR) and prognostic nutritional index (PNI), remains controversial in T1–2 rectal cancer (RC).

Methods

Clinical data of 154 T1–2 RC patients were retrospectively reviewed. The cut-off values for NLR, PLR, LMR, and PNI were determined by receiver operating characteristic curves. The relationships of these parameters with postoperative morbidities and prognosis were statistically analysed.

Results

The optimal cut-off values for preoperative NLR, PLR, LMR and PNI were 2.8, 140.0, 3.9, and 47.1, respectively. Significant but heterogeneous associations were found between NLR, PLR, LMR and PNI and clinicopathological factors. In addition, high NLR, high PLR, and low PNI were correlated with an increased postoperative morbidity rate. Patients with high NLR/PLR or low LMR/PNI had lower OS and DFS rates. On multivariate analysis, only high NLR was identified as an independent risk factor for poor DFS.

Conclusions

NLR, PLR, and PNI are valuable factors for predicting postoperative complications in T1–2 RC patients. A preoperative NLR of more than 2.8 is an independent prognostic factor for poor DFS in T1–2 RC patients.

Adverse Histologic Features in Colorectal Nonpedunculated Malignant Polyps With Nodal Metastasis

Tumor differentiation, lymphovascular invasion, margin status, polyp shape, and size are important parameters of malignant polyps (pT1) indicating possible node metastasis, which justifies a surgery. However, the size, margin, and lymphovascular invasion are often unknown or difficult to assess in a piecemeal polypectomy from a nonpedunculated malignant polyp. The aim of the study was to identify adverse histologic features in nonpedunculated malignant polyps associated with an increased risk of nodal metastasis, which may warrant a colectomy procedure. A total of 24 node-positive and 18 node-negative nonpedunculated malignant polyps and their corresponding subsequent resection specimens from 2005 to 2018 were reviewed. Cases with node metastasis were more often positive for high-grade tumor budding (70.8% vs. 16.7%; P=0.0005), poorly differentiated clusters (54.2% vs. 22.2%; P=0.0369), and both high-grade tumor budding and poorly differentiated clusters (45.8% vs. 11.1%; P=0.0160) compared with controls without nodal metastasis. High-grade tumor budding, poorly differentiated clusters, and combined high-grade tumor budding and poorly differentiated clusters increased the risk of nodal metastasis, with odds ratio of 12.1, 4.1, and 14.3, respectively. Furthermore, nodal metastasis could be seen in subsequent colectomy specimen even in completely excised malignant polyps with adverse histologic features. Our findings indicate that high-grade tumor budding and poorly differentiated clusters are important adverse histologic risk features in predicting lymph node metastatic potential. These histologic features should be reported and it may warrant a colectomy when they are present.

A classification based on tumor budding and immune score for patients with hepatocellular carcinoma

Background: The role of immune profiling and tumor budding in hepatocellular carcinoma (HCC) remains largely unknown. This study evaluated the association between tumor budding and lymphocytic infiltration in HCC. Meanwhile, HCC patients were stratified based on tumor budding grade and immune score.

Patients and methods: A total of 423 HCC patients were divided into training (n = 212) and validation (n = 211) cohort. Tumor slides from resected HCC samples were used for tumor budding assessment. A prognosis-relevant immune score was developed based on five types of immune cells out of eleven immune markers. A classification based on tumor budding grade and immune type was established (IS-TB type). To explore the association of IS-TB type and molecular alterations of HCC, 100 HCC samples and adjacent non-tumor tissues from 100 patients were investigated by whole-exome sequencing.

Results: Tumor budding was an independent adverse prognostic factor for OS and DFS in both of the training and validation cohorts (all P values <.05). The rate of high-grade tumor budding was significantly higher in HCC with immature stroma (P < .001), strong α-SMA expression (P = .005), non-steatotic tumors and non-fibrolamellar-HCC (P < .001). Additionally, tumor budding was related to both anti- and pro-tumor immune responses. Patients were classified into immune type A and immune type B according to the immune score. Based on tumor budding grade and immunotype, patients were classified into four subgroups: IS_A-TB_high (type I), IS_B-TB_high (type II), IS_A-TB_low (type III) and IS_B-TB_low (type IV). Patients with type III tumor had the best OS and DFS, whereas OS and DFS were the worst for cases with type II tumor. TP53 mutation was more frequent in IS-TB type I (IS_ATB_high) patients, while IS-TB type IV (IS_BTB_low) harbored high number of CTNNB1 mutation.

Conclusion: Tumor-immune cell interactions in HCC is heterogeneous. HCC classification based on tumor budding and immune score correlates with patient survival and molecular alterations. The defined subtypes may have significance for utilizing individualized treatment in patients with HCC.

Systemic inflammatory response predicts oncological outcomes in patients undergoing elective surgery for mismatch repair-deficient colorectal cancer

INTRODUCTION

A variety of inflammatory scoring systems and their prognostic value have been reported in many solid organ cancers. This study aimed to examine the association between the systemic and local inflammatory responses, and oncological outcomes in patients undergoing elective surgery for mismatch repair-deficient (dMMR) phenotype colorectal cancer (CRC).

MATERIALS AND METHODS

Consecutive patients undergoing resection for dMMR CRC were identified from a prospectively maintained database and compared with a cohort of patients with proficient mismatch repair system tumours. Systemic inflammatory response was assessed by the modified Glasgow prognostic score (mGPS), neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio, lymphocyte-monocyte ratio, C-reactive protein/albumin ratio, prognostic index and prognostic nutritional index. Local inflammatory response was defined by the presence of tumour infiltrating lymphocytes, tumour infiltrating neutrophils, plasma cells or macrophages at the invasive front. The inflammatory infiltrate was assessed using the Klintrup-Mäkinen (KM) score.

RESULTS

On univariable analysis, preoperative NLR ≥ 5 (hazard ratio [HR] 2.5; 95% confidence interval [CI] 1.25-5.19; p = 0.007) and mGPS (HR 1.6; 95% CI 1.1-2.6; p = 0.03) predicted worse overall survival, but only NLR was associated with greater recurrence (HR 3.6; 95% CI 1.5-8.8; p = 0.004). Increased local inflammatory response, as measured by KM score (HR 0.31; 95% CI 0.1-0.7; p = 0.009) and the presence of macrophages in the peritumoral infiltrate (HR 0.17; 95% CI 0.07-0.3; p < 0.001), was associated with better outcomes. NLR was the only independent prognostic factor of overall and disease-free survival.

CONCLUSION

Systemic inflammatory response predicts oncological outcomes in CRC patients, but only NLR has prognostic value in the dMMR group.

SMAD4 alteration associates with invasive-front pathological markers and poor prognosis in colorectal cancer

Aims

SMAD4 acts as a tumour suppressor, and the loss of SMAD4 is associated with poor prognosis in colorectal cancer (CRC) patients. Although next‐generation sequencing (NGS) enabled us to detect numerous genetic alterations in a single assay, the clinical significance of SMAD4 alteration detected with NGS has not been fully investigated. The aim of this study was to evaluate the clinicopathological characteristics and clinical significance of SMAD4 alteration detected with NGS in CRC.

Methods and results

We retrospectively investigated 201 patients with stage I–IV CRC, by using a 415‐gene panel. To analyse the relationship between SMAD4 alteration and other clinicopathological characteristics, we evaluated clinicopathological variables, including invasive‐front pathological markers: tumour budding, poorly differentiated cluster, and Crohn‐like lymphoid reaction. Fifty‐six patients (28%) had SMAD4 alteration: 24 and 32 patients had SMAD4 mutation and deletion, respectively. SMAD4 alteration was significantly associated with T category (P = 0.027), N category (P = 0.037), M category (P = 0.028), and invasive‐front pathological markers, such as poorly differentiated cluster grade 3 (P = 0.020) and absence of Crohn‐like lymphoid reaction (P = 0.004). Immunohistochemistry revealed that SMAD4 alteration was significantly associated with loss of SMAD4 (P = 0.023). In 90 patients with stage I–III disease, SMAD4 alteration was significantly associated with poor prognosis for relapse‐free and overall survival (P = 0.047; P = 0.022, respectively). Conversely, in 111 patients with stage IV disease, SMAD4 alteration was not significantly associated with overall survival.

Conclusion

SMAD4 alteration is associated with invasive‐front pathological markers and poor prognosis in stage I–III CRC patients.

Tumor Heterogeneity in Colorectal Cancer: What Do We Know So Far?

Colorectal cancer is not one disease but rather a collection of neoplastic diseases. Due to heterogeneity in the disease biology, therapy response, and prognosis, extensive disease stratification is required. Therefore, TNM stage, microsatellite status, tumor grade, lymphovascular invasion, and other parameters are assessed in the pathology report to indicate the extent and prognosis of the disease. The mutation status of KRAS, BRAF, and NRAS is also investigated in a metastatic context to predict the response to anti-EGFR therapy. Recently, 4 distinct molecular subtypes of colorectal cancer have been described that have both prognostic and therapeutic relevance. In addition, characterization of the inflammatory infiltrate revealed major differences in the amount and location of inflammatory cells in distinct colorectal tumor types. Together, all of these parameters help to stratify patients into different therapeutic and prognostic subgroups. However, this stratification is not unambiguous since tumors often display intratumoral heterogeneity, whereby several subpopulations within one tumor show differences in morphology, inflammatory infiltrate, mutational status, or gene expression profile. This article gives an overview of all of the current known data with regard to tumor heterogeneity at both inter- and intratumoral levels.