Invasion pattern and histologic features of tumor aggressiveness correlate with MMR protein expression, but are independent of activating KRAS and BRAF mutations in CRC

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.

Systematic review of tumour budding and association with common mutations in patients with colorectal cancer

INTRODUCTION

Despite a well-known prognostic role in colorectal cancer, the genomic profiling of tumour budding remains to be elucidated. We aim to review the association of common mutations with tumour budding.

METHODS

A systematic review of studies relating to tumour budding and genetic mutation in CRC was performed. The relationship between mutational status and tumour budding was evaluated using meta-analysis.

RESULTS

A total of 6153 patients from 17 articles were included. According to the meta-analysis, high-grade tumour budding was significantly associated with KRAS mutation (OR = 1.52, 95 %CI: 1.13-2.02, P = 0.005) and MSS/pMMR (OR = 2.06, 95 %CI: 1.42-2.97, P = 0.0001).

CONCLUSION

The significant association between high-grade tumour budding and mutated KRAS or MSS/pMMR may suggest a role of these mutations in the development of the tumour budding phenotype and be useful for stratifying patient outcome in CRC.

Refining the ITBCC tumor budding scoring system with a "zero-budding" category in colorectal cancer

Tumor budding scoring guidelines from the International Tumor Budding Consensus Conference (ITBCC) for colorectal cancer propose three groups: BD1 (0–4 buds/0.785 mm²), BD2 (5–9 buds/0.785 mm²), and BD3 (10 or more buds/0.785 mm²). Here, we investigate whether a fourth scoring category, namely zero buds, may have additional clinical relevance. The number of tumor buds/0.785 mm² was scored in 959 cases. Those with zero tumor buds were considered BD0, while a new BD1 category of 1–4 buds was proposed. Associations of both scoring approaches with clinicopathological features were analyzed. Conventional ITBCC scoring showed expected associations with unfavorable histopathological prognostic factors. In total, 111/959 (11.6%) were BD0. A significant difference was found when BD0 was compared statistically to BD1 (1–4 buds) for pT, TNM, tumor grade, and lymphatic, venous, and perineural invasion (p < 0.01, all). Tumors with BD0 occur relatively frequently and contribute additional information on tumor behavior. BD0 should be considered for subsequent ITBCC guidelines.

Diameter of Superior Rectal Vein - CT Predictor of KRAS Mutation in Rectal Carcinoma

Background

The purpose of this study was to investigate the feasibility of CT parameters to predict the presence of KRAS mutations in rectal cancer patients. The relationship between the presence of a KRAS mutation and pathological findings was evaluated simultaneously.

Methods

Eighty-nine patients (29 females, 60 males, age 27–90, mean 59.7±12 years) with pathologically proven rectal cancer were enrolled. A KRAS mutation test was completed following surgery. Parameters evaluated on CT included the tumor location, the diameter of the superior rectal vein (SRV) and inferior mesenteric vein (IMV), the presence of calcification, ulceration, lymph node enlargement (LNE), distant metastasis, tumor shape (intraluminal polypoid mass, infiltrative mass, or bulky), circumferential extent (C0–C1/4, C1/4–C1/2, C1/2–C3/4, or C3/4–C1), enhanced pattern (homogeneous or heterogeneous), CT ratio, and the length of the tumor (LOT). Pathological findings included lymphovascular emboli, signet ring cell, peripheral fat interval infiltration, focal ulcer, lymph node metastasis, tumor pathological type, and differentiation extent. The correlations between KRAS status and CT parameters, and KRAS status and pathological findings were investigated. The accuracy of CT characteristics for predicting KRAS mutation was evaluated.

Results

A KRAS mutation was detected in 42 cases. On CT image, the diameter of the SRV was significantly increased in the KRAS mutation group compared to in the KRAS wild-type group (4.6±0.9 mm vs 4.2±0.9 mm, p=0.02), and LNE was more likely to occur in the KRAS mutation group (73.3% vs 26.7%, p=0.03). There was no significant difference between the KRAS mutation group and the KRAS wild-type group on the other CT parameters (location, IMV, calcification, ulcer, distant metastasis, tumor shape, enhanced pattern, circumferential extent, CT ratio, and LOT). In the pathological findings, a KRAS mutation was more likely to occur in the middle differentiation group (p=0.03). No significant difference was found between the KRAS mutation group and the KRAS wild-type group in the presence of lymphovascular emboli, signet ring cell, peripheral fat interval infiltration, focal ulcer, lymph node metastasis, and tumor pathological type. With the best cut-off value of 4.07 mm, the AUC of the SRV to predict a KRAS mutation was 0.63 with a sensitivity of 76.2% and a specificity of 48.9%.

Conclusion

It was feasible to use the diameter of the SRV to predict a KRAS mutation in rectal cancer patients, and LNE also can be regarded as an important clue on preoperative CT images.

The role of tumor budding in colorectal adenocarcinoma: Possible involvement of the intestinal cancer stem cell marker Lgr5

Background

Tumor budding (TB) is a promising prognostic factor in colorectal cancer (CRC) that is independent of tumor-node-metastasis (TNM) staging. Leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5) is a stem cell marker and a member of the canonical Wnt-signaling cascade. It is involved in colorectal carcinogenesis. However, its role in CRC progression and TB needs to be clarified.

Materials and Methods

TB was assessed in both H and E and CK immunostained sections of 92 CRC cases. Associations between TB grade and different clinicopathological parameters were evaluated. Lgr5 expression in CRC cases and its association with TB grade and other clinicopathological features was also evaluated.

Results

H and E stained sections revealed low- and high-grade budding in 55 (59.8%) and 37 (40.2%) tumors, respectively, whereas Cytokeratin Immunohistochemistry (CK-IHC) showed low- and high-grade budding in 31 (33.7%) and 61 (66.3%) tumors, respectively. TB grade (in H and E and CK stained sections) was significantly associated with adverse pathological prognostic variables including vascular invasion (P = 0.03 and 0.001), lymph node metastasis (P = 0.001 and 0,001), advanced Dukes (P = 0.000 and 0.000), and TNM (P = 0.001 and 0.000) stages and inversely associated with Tumor infiltrating lymphocytes (TILS) (P = 0.02 and 0.0001) which is known to be a good prognostic indicator. Lgr5 protein was positively expressed in 52.2% (48/92) of the CRCs. Immunoreactivity of Lgr5 was significantly associated with histological grade (P = 0.01), lymph node metastasis (P = 0.002), vascular invasion (P = 0.02), TNM stage (P = 0.000), Dukes stage (P = 0.000), and TILS (P = 0.03). Furthermore, Lgr5 was found to be significantly associated with TB estimated in both H and E and CK stained tumors (P = 0.003 and 0.001 respectively).

Conclusion

This study supported the relevance of TB in the assessment of CRC aggressiveness. It also revealed that Lgr5 expression is related to morphologic features in the invasive front of CRC. Lgr5 could have an important role in forming a morphologic feature at the invasive front associated with the aggressiveness of the tumor.

Tumour budding in solid cancers

Tumour budding is an emerging prognostic biomarker in colorectal cancer (CRC) and other solid cancers. Tumour buds are usually defined as isolated single cancer cells or clusters of up to four cancer cells located at the invasive tumour front. The prognostic value of tumour budding is now supported by a large body of evidence, whereas the utility of this phenotype as a predictive biomarker remains under investigation. The application of tumour budding indices in clinical practice requires a standardized scoring system that can be tailored to specific tumour types and clinical scenarios. In the context of CRC, tumour budding can be assessed according to the method agreed at the International Tumour Budding Consensus Conference (ITBCC) in 2016. Using the ITBCC scoring system, tumour budding is an independent predictor of lymph node metastasis in patients with pT1 CRC and of unfavourable survival in patients with stage II colon cancer. Regardless of the clinical scenario or tumour type, the assertion that 'the more tumour buds, the worse the clinical outcome' applies. In this Review, we provide an overview of tumour budding in solid cancers, highlighting the molecular and biological aspects of this phenomenon, including its associations with epithelial-mesenchymal transition and features of the tumour microenvironment. We also describe the available evidence demonstrating the value of tumour budding as a biomarker across various solid cancers.

Heterogeneous nuclear ribonucleoprotein K is overexpressed and contributes to radioresistance irrespective of HPV status in head and neck squamous cell carcinoma

Radiotherapy is a major treatment option for head and neck squamous cell carcinoma (HNSCC). However, the success of radiotherapy is limited by tumor cell resistance to ionizing radiation (IR). Clinical studies have demonstrated an overall improved prognosis and higher susceptibility to radiotherapy of high‑risk human papillomavirus (HPV)‑associated HNSCC compared with classic HNSCC, as well as worse overall survival for male HNSCC patients. Overexpression of heterogeneous nuclear ribonucleoprotein (hnRNP) K has been associated with resistance to radiotherapy in melanoma and colorectal carcinoma. The aim of the present study was to analyze the impact of hnRNP K expression on the aggressiveness and radioresistance of HNSCC with respect to patient sex and HPV status. Immunohistochemical staining of HNSCC tissue specimens revealed elevated hnRNP K levels compared with those in the non‑neoplastic epithelium. Cytoplasmic hnRNP K accumulation was associated with advanced tumor stage and male sex. Exposure of HNSCC cells to IR was followed by rapid upregulation of hnRNP K at the protein level, along with re‑localization from the tumor cell nucleus to the cytoplasm. siRNA‑based knockdown of hnRNP K induced apoptosis and abolished tumor formation after xenotransplantation of HNSCC cells onto the chick egg chorioallantoic membrane (CAM). The observed effects were independent of the respective HPV status of the cell lines. These results indicated a tumorigenic and anti‑apoptotic role of hnRNP K in HNSCC, which appeared to be enhanced in male patients and contributed to the radioresistance of these tumors. However, the radioprotective effects of hnRNP K were found to be independent of the tumor's HPV status.

High-grade intratumoral tumor budding is a predictor for lymphovascular invasion and adverse outcome in stage II colorectal cancer

PURPOSE

Evaluation of tumor budding in colorectal cancer (CRC) may help to predict the tumors' metastatic potential and patients with an aggressive tumor, although not yet metastasized at time of surgery might benefit from adjuvant therapy.

METHODS

The degree of intratumoral tumor budding (ITB) was classified as low, intermediate, and high grade according to the recommendations of the International Tumor Budding Consensus Conference (ITBCC) 2016 on H&E and pankeratin-stained TMA sections from 1262 CRC, no special type (NST), including 655 stage II CRC and was correlated to clinicopathological data and overall survival.

RESULTS

Results show that higher ITB rates are significantly linked to higher tumor grade and stage, positive nodal status, lymphovascular invasion (P < 0.0001 each), absence of peritumoral lymphocytes, infiltrating type invasive tumor margin, left-sided cancer localization, and mismatch-repair proficient cancers (P < 0.05 each). In a cohort of 655 stage II CRC, ITB was associated with lymphovascular invasion (P = 0.0459) and adverse clinical outcome (P < 0.0001). In a multivariate analysis including tumor stage, tumor grade, lymphovascular invasion, ITB, and tumor localization, only low tumor stage (P = 0.0022) and absence of lymphovascular invasion (P = 0.0043) showed independent prognostic significance.

CONCLUSION

In conclusion, our findings argue towards a clinical utility of ITB as a prognostic biomarker in stage II colorectal cancer to define patients who might benefit from adjuvant therapy. ITB might be used as additional or surrogate marker in CRC in which peritumoral tumor budding is difficult to assess.

Tumor budding is an adverse prognostic marker in intestinal-type sinonasal adenocarcinoma and seems to be unrelated to epithelial-mesenchymal transition

Intestinal-type adenocarcinoma (ITAC) of sinonasal tract is a rare malignant tumor with strong morphological, immunophenotypical, and molecular similarities to colorectal adenocarcinoma (CRC). Tumor budding (TB) is a well-established adverse prognostic marker in CRC and some head and neck tumors, with features of epithelial-mesenchymal transition (EMT). The aim of this study was to assess TB in ITAC and to evaluate its possible association with EMT markers in this setting. We selected 32 surgically resected specimens of non-mucinous/non-signet ring ITAC and evaluated them for TB according to the international recommendations developed for CRC. The expression of the EMT markers E-cadherin, ZEB1, ZEB2, SLUG, and SNAIL was evaluated by immunohistochemistry (IHC). Results were stratified using clinical and follow-up data (2/32 patients had metastatic disease and 4/32 died of disease). We observed TB in 13/32 (40.6%) ITAC cases including the 7 patients with relapse (p = 0.0005) and the 4 patients dead of disease (p = 0.02). Lymphovascular invasion was associated with TB (p = 0.008). Absence of TB was associated with low ZEB2 expression (p = 0.003). No other association with EMT markers emerged. Occupational exposure to wood and leather dust was not related to the presence of TB. TB interobserver concordance was substantial (proportion of agreement = 87%; Cohen's kappa = 0.73). This work suggests that TB is associated with a worse prognosis in ITAC, but our findings do not seem to support the involvement of EMT in this specific setting. Further larger studies are needed to address this point.

RAS, Cellular Plasticity, and Tumor Budding in Colorectal Cancer

The high morbidity and mortality of colorectal cancer (CRC) remain a worldwide challenge, despite the advances in prevention, diagnosis, and treatment. RAS alterations have a central role in the pathogenesis of CRC universally recognized both in the canonical mutation-based classification and in the recent transcriptome-based classification. About 40% of CRCs are KRAS mutated, 5% NRAS mutated, and only rare cases are HRAS mutated. Morphological and molecular correlations demonstrated the involvement of RAS in cellular plasticity, which is related to invasive and migration properties of neoplastic cells. RAS signaling has been involved in the initiation of epithelial to mesenchymal transition (EMT) in CRC leading to tumor spreading. Tumor budding is the morphological surrogate of EMT and features cellular plasticity. Tumor budding is clinically relevant for CRC patients in three different contexts: (i) in pT1 CRC the presence of tumor buds is associated with nodal metastasis, (ii) in stage II CRC identifies the cases with a prognosis similar to metastatic disease, and (iii) intratumoral budding could be useful in patient selection for neoadjuvant therapy. This review is focused on the current knowledge on RAS in CRC and its link with cellular plasticity and related clinicopathological features.

Tumour budding in rectal cancer. A comprehensive review

A unique and fundamental characteristic of malignant neoplastic cells is their ability to invade other tissues and metastasise. The first step in this process is the dissociation of some of these cells from the tumour invasion front, named tumour budding (TB). This phenomenon has become increasingly relevant in recent years due to its association with adverse clinicopathological characteristics and with the epithelial-mesenchymal transition. TB has been studied by mixing colon with rectal tumours, but it is clinically important to differentiate these types of tumours. A review in two databases without language restriction was performed from 1950 to 2017 about TB with an emphasis on rectal cancer. We present various aspects of TB, from its terminology and evaluation to its molecular aspects, through its clinical associations. TB is associated with adverse clinicopathological features, like lymphovascular invasion, lymph node metastasis, and decreased survival. More studies of the clinicopathological, molecular, and epidemiological characteristics of TB in rectal cancer are needed.

KRAS and PIK3CA mutations in colorectal adenocarcinomas correlate with aggressive histological features and behavior

Tumor budding (TB) in colorectal carcinoma (CRC) is related to epithelial-mesenchymal transition and has been recently characterized as an indicator of poor prognosis along with lymphovascular tumor emboli, perineural invasion, and an infiltrative growth pattern. Mutations in the genes of the Ras-mitogen-activated protein kinase and phosphatidylinositol-4,5-bisphosphate 3-kinase pathways are associated with epithelial-mesenchymal transition and an aggressive CRC phenotype and have been used in patient stratification for anti-epidermal growth factor receptor therapies; however, the impact of these mutations on CRC morphology and behavior remains unclear. In this study, using a multigene panel, we detected KRAS, NRAS, BRAF, PIK3CA, TP53, and POLE mutations in 90 CRCs and investigated their associations with clinicopathological parameters, including TB. Our results showed that 21 of 34 tumors with high-grade TB had KRAS mutations (P=.001) and KRAS G12D and PIK3CA exon 9 variants were significantly associated with high-grade TB (P=.002 and .006, respectively); furthermore, tumors with KRAS mutations in exons 3 and 4 tended to have lymphovascular tumor emboli and perineural invasion (P=.044 and .049, respectively). PIK3CA exon 9 mutations indicated a tendency for shorter disease-free survival (P=.030), whereas BRAF mutations were associated with extracellular mucin deposition (P=.016). Our study revealed a correlation of KRAS mutations with high-grade TB, an association of certain KRAS and PIK3CA variants with aggressive clinicopathological features, as well as a possible relationship between BRAF mutations and mucin production in CRC.

KRAS, NRAS, BRAF mutations and high counts of poorly differentiated clusters of neoplastic cells in colorectal cancer: observational analysis of 175 cases

A novel grading system based on the counting of poorly differentiated clusters (PDC) of neoplastic cells at the invasive margin and in the tumour stroma was recently introduced among the histological parameters predictive of adverse clinical outcome in colorectal cancer (CRC). The aim of this study was to correlate the histological grade based on PDC and the mutational status of KRAS, NRAS and BRAF genes in 175 consecutive CRCs. The highest PDC count under the objective lens of a ×20 microscopic field in each tumour was considered for grading assessment, so that PDC counts <5, 5-9 and ≥10 PDCs were defined grade 1, grade 2 and grade 3, respectively. Hotspots mutations were identified using the MassArray platform. Overall, there were 42 (24%) mutated tumours. Mutational status was significantly associated with high pT stage (p = 0.0021), advanced pTNM stage (p = 0.0018), nodal metastases (p = 0.006), tumour budding (p = 0.022) and high PDC grade (p = 0.0022). KRAS mutations were significantly associated with PDC grade (p = 0.0379), while BRAF mutations were associated with PDC-G3 although statistical significance was not reached. No significant associations were found between NRAS and PDC. The significant association between mutated KRAS and PDC grade suggests that KRAS mutations may be involved in the formation of PDC.

Tumour budding in colorectal cancer: what do we know and what can we do?

Budding is a process during which individual or small clusters of up to five tumour cells detach from the main tumour mass and invade into the surrounding stroma. In colorectal cancer, this feature is observed in 20-40% of cases and is associated with lymphovascular invasion, lymph node and distant metastases, and poor prognosis. A variety of scoring systems for budding have been proposed but so far a gold standard is lacking, hampering implementation of a budding score in guidelines for pathological examination of colorectal cancer. Furthermore, little is known about the mechanisms which cause tumour cells to detach from the main tumour mass and obtain increased invasive potential. In this review, we present an overview of tumour budding including its definition, scoring systems, prognostic relevance and biological mechanisms involved.

Loss of RNA-binding motif protein 3 expression is associated with right-sided localization and poor prognosis in colorectal cancer

AIMS

RNA-binding motif protein 3 (RBM3) has recently been suggested as a prognostic biomarker in an array of human cancers. This study aimed to examine its effects in colorectal cancers.

METHODS AND RESULTS

RBM3 expression was analysed by immunohistochemistry on a tissue microarray containing 1800 colorectal cancers (CRCs). Nuclear RBM3 immunohistochemical staining was found in 95.9% of all interpretable CRCs. Loss of RBM3 expression was linked to advanced tumour stage (P < 0.0001), right-sided tumour localization (P < 0.0001), and poor prognosis (P = 0.0003). In a multivariable analysis including RBM3 staining, tumour grade, tumour stage, and nodal status, only tumour stage and nodal status proved to be independent prognostic markers (P < 0.0001 each), whereas the prognostic impact of RBM3 staining was not significant (P = 0.2655).

CONCLUSIONS

Our observations indicate that loss of RBM3 expression is an unfavourable prognostic marker in CRC, and is linked to right-sided tumour localization.

Lack of Association between Membrane-Type 1 Matrix Metalloproteinase Expression and Clinically Relevant Molecular or Morphologic Tumor Characteristics at the Leading Edge of Invasive Colorectal Carcinoma

Colorectal cancer (CRC) is one of the leading causes of death from cancer in the western world, but tumor biology and clinical course show great interindividual variation. Molecular and morphologic tumor characteristics, such as KRAS/BRAF mutation status, mismatch repair (MMR) protein expression, tumor growth pattern, and tumor cell budding, have been shown to be of key therapeutic and/or prognostic relevance in CRC. Membrane-type 1 matrix metalloproteinase (MT1-MMP) is a membrane-anchored zinc-binding endopeptidase that is expressed at the leading edge of various invasive carcinomas and promotes tumor cell invasion through degradation of the extracellular matrix. The aim of this study was to investigate possible associations between MT1-MMP expression and molecular tumor characteristics as well as morphologic features of tumor aggressiveness in a consecutive series of 79 CRC tissue samples. However, although MT1-MMP was expressed in 41/79 samples (52%), there was no significant association between MT1-MMP expression and KRAS/BRAF mutation status, MMR protein expression, presence of lymphovascular invasion, tumor growth pattern, tumor-infiltrating lymphocytes, or tumor cell budding in our sample cohort (P > 0.05). Thus, we conclude that although MT1-MMP may play a role in CRC invasion, it is not of key relevance to the current models of CRC invasion and aggressiveness.