Prognostic significance of tumour budding in noncolorectal gastrointestinal tract and pancreatobiliary tract: a systematic review and meta-analysis.

Tumour budding shows promise as a prognostic factor in various cancers, but its widespread application is hindered by the lack of large, validated studies and standardized criteria. This meta-analysis aims to review and examine the prognostic role of tumour budding specifically in noncolorectal gastrointestinal and pancreatobiliary tract cancers, broadening our perspective on its clinical relevance. The literature review was conducted through PubMed, Embase, and Web of Science from inception till 20 February 2023. Pooled odds ratio (OR) and hazard ratio (HR) with 95% confidence interval (CI) were calculated to assess the relation between tumour budding and clinicopathologic features, as well as overall survival. Each study was evaluated using the Newcastle-Ottawa Scale and both heterogeneity and publication bias were analysed. In this meta-analysis of 57 studies across various cancer types, multivariate HR revealed worse overall survival in oesophageal squamous cell carcinoma (HR 3.34 [95% CI 2.21-5.04]), gastric adenocarcinoma (2.03 [1.38-2.99]), pancreatic ductal adenocarcinoma (2.56 [2.02-3.25]), and biliary tract adenocarcinoma (3.11 [2.46-3.93]) with high-grade tumour budding. Additionally, high-grade tumour budding consistently correlated with adverse clinicopathological features, including lymph node metastasis, lymphovascular invasion, and distant metastasis without any observed inverse association. High heterogeneity was noted. Our study suggests that tumour budding is a valuable prognostic marker in various cancers. Nonetheless, standardized criteria tailored to specific organ types are necessary to enhance its clinical utility.

Tumour budding as a prognostic biomarker in biopsies and resections of neoadjuvant-treated rectal adenocarcinoma.

BACKGROUND: Tumour budding (TB) is a marker of tumour aggressiveness which, when measured in rectal cancer resection specimens, predicts worse outcomes and response to neoadjuvant therapy. We investigated the utility of TB assessment in the setting of neoadjuvant treatment. METHODS AND RESULTS: A single-centre, retrospective cohort study was conducted. TB was assessed using the hot-spot International Tumour Budding Consortium (ITBCC) method and classified by the revised ITBCC criteria. Haematoxylin and eosin (H&E) and AE1/AE3 cytokeratin (CK) stains for ITB (intratumoural budding) in biopsies with PTB (peritumoural budding) and ITB (intratumoural budding) in resection specimens were compared. Logistic regression assessed budding as predictors of lymph node metastasis (LNM). Cox regression and Kaplan-Meier analyses investigated their utility as a predictor of disease-free (DFS) and overall (OS) survival. A total of 146 patients were included; 91 were male (62.3%). Thirty-seven cases (25.3%) had ITB on H&E and 79 (54.1%) had ITB on CK assessment of biopsy tissue. In univariable analysis, H&E ITB [odds (OR) = 2.709, 95% confidence interval (CI) = 1.261-5.822, P = 0.011] and CK ITB (OR = 2.165, 95% CI = 1.076-4.357, P = 0.030) predicted LNM. Biopsy-assessed H&E ITB (OR = 2.749, 95% CI = 1.258-6.528, P = 0.022) was an independent predictor of LNM. In Kaplan-Meier analysis, ITB identified on biopsy was associated with worse OS (H&E, P = 0.003, CK: P = 0.009) and DFS (H&E, P = 0.012; CK, P = 0.045). In resection specimens, CK PTB was associated with worse OS (P = 0.047), and both CK PTB and ITB with worse DFS (PTB, P = 0.014; ITB: P = 0.019). In multivariable analysis H&E ITB predicted OS (HR = 2.930, 95% CI = 1.261-6.809) and DFS (HR = 2.072, 95% CI = 1.031-4.164). CK PTB grading on resection also independently predicted OS (HR = 3.417, 95% CI = 1.45-8.053, P = 0.005). CONCLUSION: Assessment of TB using H&E and CK may be feasible in rectal cancer biopsy and post-neoadjuvant therapy-treated resection specimens and is associated with LNM and worse survival outcomes. Future management strategies for rectal cancer might be tailored to incorporate these findings.

A novel grading approach predicts worse outcomes in stage pT1 non-muscle-invasive bladder cancer.

OBJECTIVE: To develop a prognostically relevant scoring system for stage pT1 non-muscle-invasive bladder cancer (NMIBC) incorporating tumour budding, growth pattern and invasion pattern because the World Health Organisation grading system shows limited prognostic value in such patients. PATIENTS AND METHODS: The tissue specimens and clinical data of 113 patients with stage pT1 NMIBC who underwent transurethral resection of bladder tumour were retrospectively investigated. Tumour budding, and growth and invasion patterns were evaluated and categorised into two grade groups (GGs). GGs and other clinical and histopathological variables were investigated regarding recurrence-free survival (RFS), progression-free survival (PFS), cancer-specific survival (CSS) and overall survival (OS) using univariable and multivariable Cox regression analyses. RESULTS: The integration of two tumour budding groups, two growth patterns, and two invasion patterns yielded an unfavourable GG (n = 28; 24.7%) that had a high impact on oncological outcomes. The unfavourable GG was identified as an independent RFS and OS predictor (P = 0.004 and P = 0.046, respectively) and linked to worse PFS (P = 0.001) and CSS (P = 0.001), irrespective of the European Association of Urology risk group. The unfavourable GG was associated with higher rates of BCG-unresponsive tumours (P = 0.006). Study limitations include the retrospective, single-centre design, diverse therapies and small cohort. CONCLUSIONS: We present a morphology-based grading system for stage pT1 NMIBC that correlates with disease aggressiveness and oncological patient outcomes. It therefore identifies a highest risk group of stage pT1 NMIBC patients, who should be followed up more intensively or receive immediate radical cystectomy. The grading incorporates objective variables assessable on haematoxylin and eosin slides and immunohistochemistry, enabling an easy-to-use low-cost approach that is applicable in daily routine. Further studies are needed to validate and confirm these results.

Buds, clusters, and transitions in 21st century colorectal carcinoma: revolution or reinvention?†.

Tumour budding (TB) describes single or small groups of neoplastic cells that lack continuity with an advancing tumour front. Poorly differentiated clusters (PDCs) are larger and qualitatively different. TB grade and PDCs may predict a worse outcome in colorectal carcinoma and other cancers and fall into the category of 'invasive front prognostic markers' that also includes intratumoural stroma type. Epithelial-mesenchymal transition (EMT) allows the adoption by epithelial cells of mesenchymal characteristics such as dyscohesion, migration, and stromal invasion. TB and PDCs harbor alterations in EMT-related proteins and RNAs and may be morphological manifestations of EMT. However, persistence of epithelioid features and absence of a full complement of typical alterations in TB and PDCs may indicate 'partial EMT', i.e. an intermediate/hybrid state. Recently, Pavlic et al asserted that TB and PDCs in colorectal cancer represent different manifestations of partial EMT and, perhaps controversially, that TB is closer than PDCs to complete transition. In clinical practice, low inter-observer agreement for invasive front prognostic markers is a potential problem. The UK colorectal cancer pathology dataset advises assessment of TB and recommends the use of an international consensus system, but time will tell if we are adopting reliable prognostic markers or reinventing the wheel. Additional studies of TB, PDCs, and EMT will presumably allow greater insight into their role in tumour development and progression. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Tumour budding in invasive breast carcinoma of no special type - relationship with clinicopathological parameters.

Each breast cancer is a heterogeneous tumour with different clinicopathological feature, and thus they all have different prognoses. Tumour budding (TB), considered as the first step in tumour metastasis, is the most critical factor for poor prognosis and is associated with the epithelial-mesenchymal transition (EMT). Tumour budding and its clinicopathological features in invasive breast carcinoma of no special type (NST). Patients who underwent surgery for invasive breast carcinoma (NST) between January 2018 and 2022 were retrospectively reviewed from the database, haematoxylin and eosin-stained slides were retrieved and reevaluated. The study included 200 patients. The mean number of TB was 12.8 ±9.6. The number of TB was significantly lower in patients who underwent neoadjuvant chemotherapy treatment ( p = 0.002). There was a weak positive correlation between TB count and tumour size ( r = 0.177). Triple-negative patients had significantly lower TB counts ( p = 0.001). No significant difference was observed between histological grade, nuclear grade, presence of ductal carcinoma in situ , stromal tumour-infiltrating lymphocytes, perineural invasion, lymph node metastasis, and number of TB ( p > 0.05). The number of TB was higher in oestrogen receptor positive tumours ( p = 0.015). There were more TB in patients with angiolymphatic invasion, which supports the pathophysiological relationship between tumour budding, metastasis, and EMT. Clarification of the mechanism of TB with more studies is promising in terms of treatment options.

Prognostic impact of tumour budding in squamous cell carcinoma of the lung: a systematic review and meta-analysis.

Tumour budding is an established prognostic factor in various solid tumours, including colorectal cancers and oral squamous cell carcinomas. However, its role is unclear and needs to be defined for squamous cell carcinoma of the lung (LSCC). Hence, we conducted a systematic review and meta-analysis investigating the prognostic role of tumour budding in LSCC. PubMed, Embase and Scopus were searched for peer-reviewed literature investigating the association between tumour budding and survival outcomes or clinicopathological variables in LSCC. The primary outcomes were pooled estimates for overall and recurrence-free survival with hazard ratio (HR) as the effect measure. The association between tumour budding and clinicopathological parameters was also investigated. Of 243 studies, nine were included, comprising 2546 patients. An increased risk of death [HR = 1.76, 95% confidence interval (CI) = 1.50-2.05, P < 0.00001] and recurrence (HR = 1.37, 95% CI = 1.12-1.68, P = 0.003) was evident in patients with high-grade tumour budding. Sensitivity and subgroup analyses revealed consistent results. Pathological stage II, lymph node metastasis, lymphovascular and pleural invasion were associated with high-grade tumour budding. Tumour budding is a new and promising prognostic factor in patients with LSCC. However, pervasive heterogeneity and publication bias reduces the credibility of these findings and the applicability of tumour budding in clinical practice. Future studies are required to standardise reporting on tumour budding in LSCC.

Tumour budding and poorly differentiated clusters in colon cancer - different manifestations of partial epithelial-mesenchymal transition.

Morphological features including infiltrative growth, tumour budding (TB), and poorly differentiated clusters (PDCs) have a firmly established negative predictive value in colorectal cancer (CRC). Despite extensive research, the mechanisms underlying different tumour growth patterns remain poorly understood. The aim of this study was to investigate the involvement of epithelial-mesenchymal transition (EMT) in TB and PDCs in CRC. Using laser-capture microdissection, we obtained distinct parts of the primary CRC including TB, PDCs, expansive tumour front, and the central part of the tumour, and analysed the expression of EMT-related markers, i.e. the miR-200 family, ZEB1/2, RND3, and CDH1. In TB, the miR-200 family and CDH1 were significantly downregulated, while ZEB2 was significantly upregulated. In PDCs, miR-141, miR-200c, and CDH1 were significantly downregulated. No significant differences were observed in the expression of any EMT-related markers between the expansive tumour front and the central part of the tumour. Our results suggest that both TB and PDCs are related to partial EMT. Discrete differences in morphology and expression of EMT-related markers between TB and PDCs indicate that they represent different manifestations of partial EMT. TB seems to be closer to complete EMT than PDCs. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Microvascular density analysis and histological parameters of oral cancer progression.

OBJECTIVES: This study aimed to investigate the role of blood and lymphatic microvascular density in the progression of oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: The sample was composed of 54 cases of OSCC. The immunoexpression to anti-alpha-smooth muscle actin (α-SMA) and to anti-endoglin (CD105) was used to determine the microvessel density (MVD); anti-podoplanin (D2-40) was used to assess the lymphatic vessel density (LVD); vascular endothelial growth factor (VEGF) was evaluated in malignant cells. The histological differentiation, the worst pattern of invasion (WPOI), tumour thickness and tumour budding (TB) intensity were assessed using haematoxylin-eosin and anti-pan-cytokeratin (AE1/AE3). Patients' age and sex, TNM classification and follow-up time were collected from the medical records. RESULTS: MVD markers presented a similar pattern of expression in blood vessels. However, only α-SMA + MVD was significantly higher among women and in tumours ≤4 cm. LVD was lower in tumours with lymph node metastasis. Regarding the histological parameters, high TB intensity was associated with histological differentiation, advanced clinical stage, greater tumour thickness and reduced disease-free survival. No difference was found in VEGF. CONCLUSIONS: The decrease in OSCC LVD could be related to pathological node involvement, whereas high TB intensity could indicate OSCC progression and worse patient outcomes.

Tumour-stroma ratio is a valuable prognostic factor for oral tongue squamous cell carcinoma.

OBJECTIVE: The objectives of this study were to estimate the prognostic value of the tumour-stroma ratio (TSR) and tumour budding (TB) in oral tongue squamous cell carcinoma (OTSCC) and to establish a reliable model to predict the outcome of OTSCC patients. METHODS: A total of 103 patients surgically treated at our hospital were enrolled in this study. Chi-square tests, Kaplan-Meier analyses and Cox proportional hazards regression models were performed for statistical analysis. RESULTS: Fifty-six patients were categorized as stroma-rich, and 47 patients were categorized as stroma-poor. Only pathological grade was associated with the TSR (p = 0.017). Kaplan-Meier analysis showed that stroma-rich, high-intensity budding and high risk groups were associated with worse prognosis. The Cox regression model showed that the TSR was an independent risk factor for OTSCC patients prognosis, and the high risk group was also related to poor prognosis (p < 0.05). TB was significantly associated with poor prognosis but was not an independent risk factor. CONCLUSIONS: We found that patients in the stroma-rich group had a worse long-term prognosis. The TSR is an independent risk factor for OTSCC patients' outcome. In addition, a risk model that combined the TSR and TB proved to be valuable for predicting OTSCC patients' outcome.

Tumour budding in cutaneous squamous cell carcinoma: A novel prognosis risk factor.

INTRODUCTION: Most cutaneous squamous cell carcinomas (cSCC) have a good prognosis, there is a small group where metastasis and death occur and the evaluation of this risk is still cause for controversy. Tumour budding is a pattern of histological invasion that is an emerging risk factor in other solid tumours. OBJECTIVE: To examine the association between tumour budding and other known high-risk predictors in cSCC. In addition, the impact of tumour budding on overall survival (OS) and disease-specific survival (DSS) was analysed. METHOD: Retrospective study. It included patients with a diagnosis of non-genital cSCC by excisional biopsy at a university hospital, between 2010 and 2020. A pathologist re-analysed their histological slides and evaluated budding. Univariate and multivariate analyses were made to study the associations. RESULTS: 156 cSCC biopsies were found, and positive tumour budding was found in 13.5%. This correlated with worse DSS and OS. On univariate analysis, budding was correlated with the diameter, thickness of the tumour, histological grade, level of invasion, perineural and lymphovascular invasion, previous radiotherapy, recurrent tumours and lymph node metastasis (LNM). Multivariate analysis: tumour budding was associated with poorly differentiated tumours, prior radiotherapy and LNM. CONCLUSION: An association was found between tumour budding and most known risk factors in cSCC. We found findings that indicate that the presence of tumour budding is associated with a worse prognosis in terms of LNM, OS and DSS. This supports the results of previous work which has suggested that budding could be related to high-risk cSCC.

Tumour budding - an additional prognostic factor in colorectal cancer survival.

Tumour budding (TB) in cancer is a phenomenon of tumour cells forming clusters, and it is associated with an epithelial-mesenchymal transition into the extracellular matrix of the tumour. It has been shown that the presence of TB in colorectal cancer (CRC) is associated with worse overall survival, higher possibility for vessel invasion, lymph node involvement, and distant metastases appearance. In this retrospective study TB presence in operated patients for CRC is analysed. In the data from 81 patients, 26 presented with TB. Analysis revealed high statistical significance of the effect of TB presence on the number of metastatic lymph nodes, and the lymphovascular and perineural invasion. A statistically meaningful correlation was found between the presence of TB and CRC survival ( p = 0.016). Patients with right-sided colon cancer presented with worse overall survival ( p = 0.011). The patients who presented lymph node metastases and TB presence had worse overall survival ( p = 0.026 and p = 0.021, respectively). Tumour budding, tumour location, and age over 64 years are found to be the independent prognostic factors in CRC patients. Tumour budding is an important prognostic factor in CRC patients that will contribute to treatment. Pathological examination must consider TB in detail.

Prognostic significance of tumour budding in Merkel cell carcinoma.

Prognostic factors in Merkel cell carcinoma (MCC) are scarce. Tumour budding (TB) has been shown to have a prognostic role in different cancers but has not been explored in MCC. We aimed to determine if TB influences survival in MCC. We performed a retrospective evaluation of 45 cases of MCC in a cancer centre. This included a survival analysis involving TB in patients with MCC, and we searched for variables associated with TB. The mean age of the patients was 69 years. Histologically, the average Breslow was 11.36 mm, and the mean mitotic rate was 31.9 mitoses/mm2. The diagnosis was made in clinical stages I and II in 40% of cases, 22.2% in stage III, and 37.8% in stage IV. Tumour budding was low ( 10 buds/0.785 mm2) in 24.4%. There were no clinical or pathological features associated with high TB. Among the prognostic factors for 5-year survival, we found that tumour size and clinical stage were statistically associated with survival (p = 0.031 and 0.021), but TB was not. No clinical or pathological characteristics of MCC are associated with any degree of TB. Tumour budding does not influence overall survival.

Development of a semi-automated method for tumour budding assessment in colorectal cancer and comparison with manual methods.

AIMS: Tumour budding (TB) is an established prognostic feature in multiple cancers but is not routinely assessed in pathology practice. Efforts to standardise and automate assessment have shifted from haematoxylin and eosin (H&E)-stained images towards cytokeratin immunohistochemistry. The aim of this study was to compare manual H&E and cytokeratin assessment methods with a semi-automated approach built within QuPath open-source software. METHODS AND RESULTS: TB was assessed in cores from the advancing tumour edge in a cohort of stage II/III colon cancers (n = 186). The total numbers of buds detected with each method were as follows: manual H&E, n = 503; manual cytokeratin, n = 2290; and semi-automated, n = 5138. More than four times the number of buds were identified manually with cytokeratin assessment than with H&E assessment. One thousand seven hundred and thirty-four individual buds were identified with both manual and semi-automated assessments applied to cytokeratin images, representing 75.7% of the buds identified manually (n = 2290) and 33.7% of the buds detected with the semi-automated method (n = 5138). Higher semi-automated TB scores were due to any discrete area of cytokeratin immunopositivity within an accepted area range being identified as a bud, regardless of shape or crispness of definition, and to the inclusion of tumour cell clusters within glandular lumina ('luminal pseudobuds'). Although absolute numbers differed, semi-automated and manual bud counts were strongly correlated across cores (ρ = 0.81, P < 0.0001). All methods of TB assessment demonstrated poorer survival associated with higher TB scores. CONCLUSIONS: We present a new QuPath-based approach to TB assessment, which compares favourably with established methods and offers a freely available, rapid and transparent tool that is also applicable to whole slide images.

Combined assessment of tumour cell nest size and desmoplastic reaction as an excellent prognostic predictor in oesophageal squamous cell carcinoma.

AIMS: Tumour budding (TB) activity, cell nest size (CNS), and desmoplastic reaction (DR) have been confirmed to be significantly correlated with prognosis in oesophageal squamous cell cancer (ESCC) recently. However, there are limited data on the prognostic significance of combined assessment of cellular dissociation and tumour stroma in ESCC. METHODS: In all, 265 cases with resected ESCCs diagnosed between January 2018 and August 2019 were retrospectively reviewed. All slides were reviewed for assessing TB, CNS, and DR. The Cellular Dissociation Grading and our Combined CNS and DR (CNS/DR) Grading systems were adopted to re-grade ESCCs. RESULTS: High TB activity, small CNS, and immature DR had a strong association with shorter overall survival (OS) and progression-free survival (PFS) (P < 0.001, respectively) in ESCC. Combined assessment of CNS and DR in a 4-tiered grading system displayed a prognostic excellence for survival (P < 0.001), and outperformed the Cellular Dissociation Grading for both OS (area under the curve [AUC], 0.728 versus 0.644, P = 0.043) and PFS (AUC, 0.763 versus 0.667, P = 0.018) by receiver operator characteristic curves. Also, Combined CNS/DR Grading showed superiority in recognizing a G4 subgroup with the worst outcome in our cohort, to whom the most urgent attention needs to be called. CONCLUSIONS: This is the first study to propose a novel Combined Grading system based on CNS and DR in ESCC, which has been demonstrated to be relatively superior to Cellular Dissociation Grading in predicting prognosis. The findings shed new light on the histopathological grading of ESCC and facilitates identifying biologically aggressive ESCCs.

The relationship between primary colorectal cancer histology and the histopathological growth patterns of corresponding liver metastases.

BACKGROUND: The histopathological growth patterns (HGPs) are a prognostic and predictive biomarker in colorectal cancer liver metastasis (CRLM). This study evaluates the relationship between the HGP and primary colorectal cancer (CRC) histopathology. METHODS: A total of 183 treatment-naive patients with resected CRC and CRLM were included. Thirteen CRC histopathology markers were determined and compared between the desmoplastic and non-desmoplastic HGP; tumour sidedness, pT&pN stage, tumour grade, tumour deposits, perineural- (lympho-)vascular- and extramural venous invasion, peritumoural budding, stroma type, CRC growth pattern, Crohn's-like lymphoid reaction, and tumour-infiltrating lymphocyte (TIL) density. Logistic regression analysis was performed using both CRC and CRLM characteristics. RESULTS: Unfavourable CRC histopathology was more frequent in non-desmoplastic CRLM for all markers evaluated, and significantly so for a lower TIL density, absent Crohn's-like lymphoid reaction, and a "non-mature" stroma (all p < 0.03). The cumulative prevalence of unfavourable CRC histopathology was significantly higher in patients with non-desmoplastic compared to desmoplastic CRLM, with a median (IQR) of 4 (3-6) vs 2 (1-3.5) unfavourable characteristics observed, respectively (p < 0.001). Multivariable regression with 9 CRC histopathology markers and 2 CRLM characteristics achieved good discriminatory performance (AUC = 0.83). CONCLUSIONS: The results of this study associates primary CRC histopathology with the HGP of corresponding liver metastases.

Molecular mechanisms of tumour budding and its association with microenvironment in colorectal cancer.

Colorectal cancer (CRC) is the third most common cancer worldwide. Poor survival of CRC associated with the development of tumour metastasis led to the investigation of the potential biomarkers to predict outcomes in CRC patients. Tumour budding (TB) is a well-known independent prognostic marker for poor survival and disease metastasis. Therefore, it has been suggested that TB status is included in routine clinicopathological factors for risk assessment in CRC. In contrast with a vast majority of studies regarding the prognostic power of TB, there is no clear evidence pertaining to the underlying molecular mechanism driving this phenotype, or an understanding of TB relationship with the tumour microenvironment (TME). The aim of the present study is to present a comprehensive review of TB and tumour cell signalling pathways together with the cross-talk of immune cells that could drive TB formation in CRC.

The budding and depth of invasion model in oral cancer: A systematic review and meta-analysis.

BACKGROUND: Tumour budding (B) and depth of invasion (D) have both been reported as promising prognostic markers in oral squamous cell carcinoma (OSCC). This meta-analysis assessed the prognostic value of the tumour budding and depth of invasion combination (BD model) in OSCC. METHODS: Databases including Ovid MEDLINE, PubMed, Scopus and Web of Science were searched for articles that studied the BD model as a prognosticator in OSCC. PICO search strategy was "In OSCC patients, does BD model have a prognostic power?" We used the reporting recommendations for tumour marker prognostic studies (REMARK) criteria to evaluate the quality of studies eligible for systematic review and meta-analysis. RESULTS: Nine studies were relevant as they analysed the BD model for prognostication of OSCC. These studies used either haematoxylin and eosin (HE) or pan-cytokeratin (PCK)-stained resected sections of OSCC. Our meta-analysis showed a significant association of BD model with OSCC disease-free survival (hazard ratio = 2.02; 95% confidence interval = 1.44-2.85). CONCLUSIONS: The BD model is a simple and reliable prognostic indicator for OSCC. Evaluation of the BD model from HE- or PCK-stained sections could facilitate individualized treatment planning for OSCC patients.

Taking tumour budding to the next frontier - a post International Tumour Budding Consensus Conference (ITBCC) 2016 review.

Tumour budding in colorectal cancer, defined as single tumour cells or small clusters containing four or fewer tumour cells, is a robust and independent biomarker of aggressive tumour biology. On the basis of published data in the literature, the evidence is certainly in favour of reporting tumour budding in routine practice. One important aspect of implementing tumour budding has been to establish a standardised and evidence-based scoring method, as was recommended by the International Tumour Budding Consensus Conference (ITBCC) in 2016. Further developments have aimed at establishing methods for automated tumour budding assessment. A digital approach to scoring tumour buds has great potential to assist in performing an objective budding count but, like the manual consensus method, must be validated and standardised. The aim of the present review is to present general considerations behind the ITBCC scoring method, and a broad overview of the current situation and challenges regarding automated tumour budding detection methods.

Development and initial validation of a deep learning algorithm to quantify histological features in colorectal carcinoma including tumour budding/poorly differentiated clusters.

AIMS: To develop and validate a deep learning algorithm to quantify a broad spectrum of histological features in colorectal carcinoma. METHODS AND RESULTS: A deep learning algorithm was trained on haematoxylin and eosin-stained slides from tissue microarrays of colorectal carcinomas (N = 230) to segment colorectal carcinoma digitised images into 13 regions and one object. The segmentation algorithm demonstrated moderate to almost perfect agreement with interpretations by gastrointestinal pathologists, and was applied to an independent test cohort of digitised whole slides of colorectal carcinoma (N = 136). The algorithm correctly classified mucinous and high-grade tumours, and identified significant differences between mismatch repair-proficient and mismatch repair-deficient (MMRD) tumours with regard to mucin, inflammatory stroma, and tumour-infiltrating lymphocytes (TILs). A cutoff of >44.4 TILs per mm2 carcinoma gave a sensitivity of 88% and a specificity of 73% in classifying MMRD carcinomas. Algorithm measures of tumour budding (TB) and poorly differentiated clusters (PDCs) outperformed TB grade derived from routine sign-out, and compared favourably with manual counts of TB/PDCs with regard to lymphatic, venous and perineural invasion. Comparable associations were seen between algorithm measures of TB/PDCs and manual counts of TB/PDCs for lymph node metastasis (all P < 0.001); however, stronger correlations were seen between the proportion of positive lymph nodes and algorithm measures of TB/PDCs. Stronger associations were also seen between distant metastasis and algorithm measures of TB/PDCs (P = 0.004) than between distant metastasis and TB (P = 0.04) and TB/PDC counts (P = 0.06). CONCLUSIONS: Our results highlight the potential of deep learning to identify and quantify a broad spectrum of histological features in colorectal carcinoma.

Tumour budding and CD8+ T cells: 'attackers' and 'defenders' in rectal cancer with and without neoadjuvant chemoradiotherapy.

AIM: Tumour budding ('attacker') and CD8+ T cells ('defender') are recognised as important parameters for risk stratification in colon cancers and, combined, may have an even stronger clinical impact. Here, we determine the value of tumour budding and CD8+ in rectal cancer patients treated with/without neoadjuvant therapy. METHODS AND RESULTS: Using digital scans of all tumour slides/case, we analysed CD8+ T cell counts in two patient cohorts: 45 neoadjuvantly treated and 47 primarily surgically treated (totalling n = 543 slides) after double-staining of the surgical resection specimen for pan-cytokeratin and CD8+ . Tumour buds in hot-spots were manually counted (area = 0.785 mm2 ) and CD8+ T cell counts were analysed separately both in tumour budding hot-spots and the densest CD8+ regions throughout the tumour. In neoadjuvantly treated patients, only tumour budding and not CD8+ T cells was associated with tumour features, including more advanced ypT (P = 0.0062), venous invasion (P = 0.002), lymphatic invasion (P = 0.0003) and perineural invasion (P = 0.0017), as well as higher American Joint Committee on Cancer (AJCC) tumour regression score (P = 0.0035), indicating less tumour response. Overall survival was also worse in patients with high-grade budding in univariate analysis only. In contrast, all three variables, namely tumour budding (P = 0.0347), CD8+ T cells in budding hot-spots (P = 0.0382) and CD8+ T cells in the densest areas (P = 0.0117) were also associated with worse (budding) and better (CD8) survival time in the multivariate setting. CONCLUSION: In rectal cancer, tumour budding has clinical relevance in both primarily surgically treated patients and in those with neoadjuvantly treated patients, where it characterises highly aggressive residual disease. CD8+ T cell counts appear not to have prognostic relevance in the neoadjuvant context.