Self-supervised learning (SSL) automates the extraction and interpretation of histopathology features on unannotated hematoxylin-eosin-stained whole slide images (WSIs). We train an SSL Barlow Twins encoder on 435 colon adenocarcinoma WSIs from The Cancer Genome Atlas to extract features from small image patches (tiles). Leiden community detection groups tiles into histomorphological phenotype clusters (HPCs). HPC reproducibility and predictive ability for overall survival are confirmed in an independent clinical trial ( N = 1213 WSIs). This unbiased atlas results in 47 HPCs displaying unique and shared clinically significant histomorphological traits, highlighting tissue type, quantity, and architecture, especially in the context of tumor stroma. Through in-depth analyses of these HPCs, including immune landscape and gene set enrichment analyses, and associations to clinical outcomes, we shine light on the factors influencing survival and responses to treatments of standard adjuvant chemotherapy and experimental therapies. Further exploration of HPCs may unveil additional insights and aid decision-making and personalized treatments for colon cancer patients.

AIMS:Tumour-stroma ratio (TSR) scores of biopsy material in rectal carcinoma (RC) could aid a biomarker-based, upfront and personalised treatment strategy selection for RC patients. In a large retrospective, multicentre cohort, we aimed to validate the predictive value of biopsy-scored TSR on neoadjuvant therapy response, and secondarily, disease-free and overall survival (DFS, OS). METHODS AND RESULTS:Scanned haematoxylin and eosin-stained RC biopsy slides were collected from Leiden University Medical Center (N = 116) and from the clinical PROCTOR-SCRIPT (N = 142) and RAPIDO (N = 271) trials. TSR was scored per protocol and categorised as stroma-low (≤ 50%) or stroma-high (> 50%). Major response was defined as tumour regression grade (TRG) 1 + 2 by Mandard, including pathological complete response. Ultimately, a large and varied cohort with 373 RC patients was established. Locally advanced RC was more often stroma-high (P < 0.001). We subsequently observed significantly lower major response rates in the stroma-high RC after a neoadjuvant treatment approach (hazard ratio = 0.63, 95% confidence interval = 0.41-0.99; P = 0.044). Despite correction for well-known risk factors in Cox hazard regression analysis, such as (y)pTNM substages or residual tumour status, the TSR had no singular significant influence on DFS nor OS in multivariate analysis (P = 0.438; P = 0.934, respectively). CONCLUSIONS:Biopsy-scored TSR can predict neoadjuvant therapy efficacy, as RC patients with stroma-high biopsies show less major response. However, patient survival is multifactorial, although response is an important predictor, influenced by TSR. Scoring TSR on RC biopsy material is a reliable histological parameter, implementation of which in treatment guidelines could improve upfront selection for a watch-and-wait strategy.

BACKGROUND:Colorectal cancer is highly prevalent. The stromal tumour microenvironment significantly influences tumour behaviour, and cancer-associated fibroblasts (CAFs), as major component of tumour stroma, are increasingly studied. Specifically, CAF-marker fibroblast activation protein (FAP) is gaining interest as tracer for imaging using radiolabelled FAP-inhibitor (FAPI). We describe patterns of FAP-expression, and associations to intratumoural stroma amount, establishing a biological background and potential future reference to pathology assessment. MATERIALS AND METHODS:Archival histological material from 125 stage-II/III CRC patients was collected. Haematoxylin-and-eosin staining was performed to determine the tumour-stroma ratio (TSR), indicating stromal percentages in primary tumours, lymph nodes (LNs) and biopsies. On immunohistochemistry stains, FAP-expression was semiquantitatively scored as little-no, heterogeneous, or moderate-high expression. Correlation of TSR and FAP-expression with Chi-square testing was assessed. Other patterns were also described, e.g. tumour epithelial FAP-expression. RESULTS:In total, 93 patients (40 stage-III colon [CC], 53 stage-II/III RC) were included. Correlation between 41 (44 %) stroma-high CRC (18/40 CC, 45 %; 23/53 RC, 43 %) with high FAP-expression was not significant (P = 0.428 CRC; P = 0.470 CC; P = 0.615 RC). The majority of CRC had any FAP-expression (78 CRC, 84 %), mostly the invasive front, and in most associated LN metastases (87 % CRC tumour-positive LN). However, FAP-expression was often heterogeneous, even staining healthy colon and lymphoid tissue. CONCLUSIONS:CRCs and LN metastases generally express FAP, but levels vary significantly between and within tumours and have no direct correlation with TSR. Care has to be taken translating FAPI-PET/CT results with e.g. disease extent and activity, emphasizing the importance of multidisciplinary approach.

The recently developed fibroblast activation protein inhibitor (FAPI) tracer for PET/CT, binding tumour-stromal cancer-associated fibroblasts, is a promising tool for detection of positive lymph nodes. This study provides an overview of features, including sizes and tumour-stromal content, of lymph nodes and their respective lymph node metastases (LNM) in colorectal cancer (CRC), since literature lacks on whether LNMs contain sufficient stroma to potentially allow FAPI-based tumour detection. Haematoxylin and eosin-stained tissue slides from 73 stage III colon cancer patients were included. Diameters and areas of all lymph nodes and their LNMs were assessed, the amount of stroma by measuring the stromal compartment area, the conventional and total tumour-stroma ratios (TSR-c and TSR-t, respectively), as well as correlations between these parameters. Also, subgroup analysis using a minimal diameter cut off of 5.0 mm was performed. In total, 126 lymph nodes were analysed. Although positive correlations were observed between node and LNM for diameter and area (r = 0.852, p < 0.001 and r = 0.960, p < 0.001, respectively), and also between the LNM stromal compartment area and nodal diameter (r = 0.612, p < 0.001), nodal area (r = 0.747, p < 0.001) and LNM area (r = 0.746, p < 0.001), novel insight was that nearly all (98%) LNMs contained stroma, with median TSR-c scores of 35% (IQR 20–60%) and TSR-t of 20% (IQR 10–30%). Moreover, a total of 32 (25%) positive lymph nodes had a diameter of < 5.0 mm. In LNMs, stroma is abundantly present, independent of size, suggesting a role for FAPI PET/CT in improved lymph node detection in CRC.

Liquid biopsy has emerged as a novel approach to tumor characterization, offering advantages in sample accessibility and tissue heterogeneity. However, as mutational analysis predominates, the tumor microenvironment has largely remained unacknowledged in liquid biopsy research. The current work provides an explorative transcriptomic characterization of the Stroma Liquid BiopsyTM (SLB) proteomics panel in colon carcinoma by integrating single-cell and bulk transcriptomics data from publicly available repositories. Expression of SLB genes was significantly enriched in tumors with high histologic stromal content in comparison to tumors with low stromal content (median enrichment score 0.308 vs. 0.222, p = 0.036). In addition, we identified stromal-specific and epithelial-specific expression of the SLB genes, that was subsequently integrated into a gene signature ratio. The stromal-epithelial signature ratio was found to have prognostic significance in a discovery cohort of 359 colon adenocarcinoma patients (OS HR 2.581, 95%CI 1.567-4.251, p < 0.001) and a validation cohort of 229 patients (OS HR 2.590, 95%CI 1.659-4.043, p < 0.001). The framework described here provides transcriptomic evidence for the prognostic significance of the SLB panel constituents in colon carcinoma. Plasma protein levels of the SLB panel may reflect histologic intratumoral stromal content, a poor prognostic tumor characteristic, and hence provide valuable prognostic information in liquid biopsy.

Background: This international multicenter study aims to validate the tumor-stroma ratio (TSR) as prognostic parameter in colon cancer, preparing it for implementation in current routine pathology diagnostics in addition to the TNM classification.

The best current biomarker strategies for predicting response to immune checkpoint inhibitor (ICI) therapy fail to account for interpatient variability in response rates. The histologic tumor–stroma ratio (TSR) quantifies intratumoral stromal content and was recently found to be predictive of response to neoadjuvant therapy in multiple cancer types. In the current work, we predicted the likelihood of ICI therapy responsivity of 335 therapy-naive colon adenocarcinoma tumors from The Cancer Genome Atlas, using bioinformatics approaches. The TSR was scored on diagnostic tissue slides, and tumor-infiltrating immune cells (TIICs) were inferred from transcriptomic data. Tumors with high stromal content demonstrated increased T regulatory cell infiltration (p = 0.014) but failed to predict ICI therapy response. Consequently, we devised a hybrid tumor microenvironment classification of four stromal categories, based on histological stromal content and transcriptomic-deconvoluted immune cell infiltration, which was associated with previously established transcriptomic and genomic biomarkers for ICI therapy response. By integrating these biomarkers, stroma-low/immune-high tumors were predicted to be most responsive to ICI therapy. The framework described here provides evidence for expansion of current histological TIIC quantification to include the TSR as a novel, easy-to-use biomarker for the prediction of ICI therapy response.

Study Design: Systematic review with meta-analysis. Objective: Additional anterior stabilization might prevent posterior implant failure, but over time, the disadvantageous of bone grafts have become evident. The objective of this systematic review was to compare risks and advantages of additional anterior stabilization with a titanium cage to solely posterior fixation for traumatic thoracolumbar fractures. Methods: An electronic search was performed in the literature from 1980 to March 2016. Studies comparing only posterior with anteroposterior fixation by means of a titanium cage were included in this study. Data extraction and Cochrane risk of bias assessment were done by two independent authors. In addition, the PRISMA statement was followed, and the GRADE approach was used to present results. Results: Of the 1584 studies, two randomized controlled trials (RCTs) and one retrospective cohort study were included in the meta-analysis. The RCTs reported evidence of high quality that anteroposterior stabilization maintained better kyphosis correction than posterior stabilization alone. However, these results were neutralized in the meta-analysis by the cohort study. Implant failure was reported by one study, in the posterior group. No differences in follow-up visual analog scale scores, neurologic improvement, and complications were found. Operation time, blood loss, and hospital stay all increased in the anteroposterior group. Conclusions: Patients with a highly comminuted or unstable fracture could benefit from combined anteroposterior stabilization with a titanium cage, for some evidence suggests this prevents loss of correction. However, large randomized studies still lack. There is a risk of cage subsidence, and increased perioperative risks have to be considered when choosing the optimal treatment.