Gastric cancer molecular classification based on immunohistochemistry and in-situ hybridisation and mortality.

BACKGROUND AND AIMS: Gastric cancers (GC) are divided into subtypes based on molecular profile: Epstein-Barr virus (EBV)-positive, microsatellite instability (MSI), chromosomal instability (CIN) and genomically stable (GS) tumours. The prognostic impact of this classification is unclear. The aim was to evaluate whether the molecular subtypes determined using in-situ hybridisation (ISH) and immunohistochemistry (IHC) are associated with clinicopathological parameters and prognosis. METHODS AND RESULTS: The study included 503 GC patients. Based on ISH (EBV) and IHC (MSI and TP53), tumours were divided into EBV-positive, MSI, CIN (EBVneg/MSS/TP53aberrant) and GS (EBVneg/MSS/TP53wild-type) subgroups. Survival analyses with intestinal- and diffuse-type tumours were examined separately. EBV-positive tumours associated with male sex. Both EBV-positive and MSI tumours associated with intestinal type. CIN tumours associated with intestinal-type and positive lymph node status. GS tumours associated with diffuse-type and negative lymph node status. In the total cohort, no significant differences in the 5-year survival were observed. In intestinal tumours, the 5-year survival was better in EBV-positive tumours compared with GS tumours [hazard ratio (HR) = 0.57, 95% confidence interval (CI) = 0.33-0.99]. In diffuse tumours, the 5-year survival was worse in CIN tumours compared with GS tumours (HR = 1.57, 95% CI = 1.14-2.18). In radically resected diffuse tumours, the 5-year survival was worse in MSI tumours compared with GS tumours (HR = 3.26, 95% CI = 1.20-8.82). CONCLUSIONS: The molecular classification is associated with histological type but not prognosis in GC. As the prognostic effects of molecular subtypes in intestinal- and diffuse-type cancers may differ, combining histological and molecular information is recommended for future studies.

Toll-like receptors 1, 2, 4, 5, and 6 in gastric cancer.

Toll-like receptors (TLRs) are expressed on both immune cells and tumor cells, triggering both anti-tumor and pro-tumor responses. Therefore, TLRs have potential as prognostic biomarkers and immunotherapeutic targets. The aim of this study was to investigate TLR1, TLR2, TLR4, TLR5, and TLR6 expression and association with clinicopathological variables and survival in gastric cancer. Immunohistochemical study on cancer specimens from 564 resected gastric cancer patients was performed using tissue microarrays. The association between patient survival and TLR expression was calculated with Cox regression adjusted for confounding factors. Patients with high cytoplasmic TLR2 expression had significantly poorer 5-year survival than the low cytoplasmic TLR2 expression group in multivariate analysis (adjusted HR 1.38, 95% CI 1.11-1.71), and this estimate was similar in intestinal type (adjusted HR 1.33, 95% CI 0.98-1.80) and diffuse type (adjusted HR 1.48, 95% CI 1.06-2.05) histology subgroups. Patients with high cytoplasmic TLR6 expression group had significantly better 5-year survival compared with low cytoplasmic TLR6 expression group in multivariate analysis (adjusted HR 0.74, 95% CI 0.60-0.91). In the subgroup analysis of diffuse type of histology, the 5-year survival was better in high cytoplasmic TLR6 expression group in multivariable analysis (HR 0.62, 95% CI 0.46-0.83). In the intestinal type of histology subgroup, no significant differences between the groups were present. TLR1, TLR4, and TLR5 expression were not associated with 5-year survival. In conclusion, cytoplasmic TLR2 and TLR6 expression seem to have independent prognostic impact in gastric cancer, while TLR1, TLR4, and TLR5 do not.

Optimized detection and segmentation of nuclei in gastric cancer images using stain normalization and blurred artifact removal.

Histological analysis with microscopy is the gold standard to diagnose and stage cancer, where slides or whole slide images are analyzed for cell morphological and spatial features by pathologists. The nuclei of cancerous cells are characterized by nonuniform chromatin distribution, irregular shapes, and varying size. As nucleus area and shape alone carry prognostic value, detection and segmentation of nuclei are among the most important steps in disease grading. However, evaluation of nuclei is a laborious, time-consuming, and subjective process with large variation among pathologists. Recent advances in digital pathology have allowed significant applications in nuclei detection, segmentation, and classification, but automated image analysis is greatly affected by staining factors, scanner variability, and imaging artifacts, requiring robust image preprocessing, normalization, and segmentation methods for clinically satisfactory results. In this paper, we aimed to evaluate and compare the digital image analysis techniques used in clinical pathology and research in the setting of gastric cancer. A literature review was conducted to evaluate potential methods of improving nuclei detection. Digitized images of 35 patients from a retrospective cohort of gastric adenocarcinoma at Oulu University Hospital in 1987-2016 were annotated for nuclei (n = 9085) by expert pathologists and 14 images of different cancer types from public TCGA dataset with annotated nuclei (n = 7000) were used as a comparison to evaluate applicability in other cancer types. The detection and segmentation accuracy with the selected color normalization and stain separation techniques were compared between the methods. The extracted information can be supplemented by patient's medical data and fed to the existing statistical clinical tools or subjected to subsequent AI-assisted classification and prediction models. The performance of each method is evaluated by several metrics against the annotations done by expert pathologists. The F1-measure of 0.854 ± 0.068 is achieved with color normalization for the gastric cancer dataset, and 0.907 ± 0.044 with color deconvolution for the public dataset, showing comparable results to the earlier state-of-the-art works. The developed techniques serve as a basis for further research on application and interpretability of AI-assisted tools for gastric cancer diagnosis.

Toll-like receptors 3, 7, 8, and 9 in gastric cancer.

Toll-like receptors (TLRs) have been shown to have anti-tumor, pro-tumor, or even dual effects in cancer, and are thus potential prognostic biomarkers and immunotherapeutic targets. The present study aimed to evaluate associations between endosomal TLRs, namely TLR3, TLR7, TLR8, and TLR9, expression and clinicopathological variables and survival in gastric cancer. A total of 564 gastric adenocarcinoma patients were included in this retrospective cohort study. Samples and clinicopathological data were retrieved and organized into tissue microarray blocks. Protein expressions were detected by immunohistochemical staining. The patients were divided into low expression and high expression groups by median values of expression. Cox regression provided hazard ratios (HR) with 95% confidence intervals (CI), adjusted for confounders. Patients with high nuclear TLR3 expression had significantly poorer 5-year survival than the low nuclear TLR3 expression group in the univariable analysis (crude HR 1.31, 95% CI 1.07-1.60). With radically resected patients, poor prognosis was also seen in the multivariable analysis (adjusted HR 1.38, 95% CI 1.08-1.77). Cytoplasmic TLR3, TLR7, TLR8, and TLR9 were not associated with 5-year survival. In conclusion, high nuclear TLR3 expression seems to have prognostic impact in gastric cancer, while TLR7, TLR8, and TLR9 do not.

Monocarboxylate Transporters 1 and 4 and MTCO1 in Gastric Cancer.

Background: Monocarboxylate transporters (MCTs) appear to play an important role in tumor development and aggressiveness. The present study aimed to evaluate associations between cytoplasmic MCT1, MCT4, and mitochondrial cytochrome c oxidase (MTCO1) expression and clinicopathological variables or survival in gastric cancer. Material and methods: A total of 568 gastric adenocarcinoma patients were included in this retrospective cohort study. Protein expressions were detected by immunohistochemical staining. The patients were divided into low expression and high expression groups by median value. The Chi-squared test was used to compare categorical variables. The T-test was used to compare continuous variables. Expressions were analyzed in relation to 5-year survival and overall survival. Cox regression provided HRs and 95% CIs, adjusted for confounders. Results: High cytoplasmic MCT1 expression was associated statistically significantly with higher T-class (p = 0.020). High cytoplasmic MCT4 expression was associated statistically significantly with positive lymph node status (p = 0.005) and was more common in Lauren's intestinal type (p < 0.001). Low cytoplasmic MTCO1 expression was associated statistically significantly with positive distant metastases (p = 0.030), and high cytoplasmic MTCO1 expression was associated more often with intestinal type (p = 0.044). However, MCT1, MCT4, and MTCO1 were not associated with survival. Conclusions: Monocarboxylate receptors seem to be associated with gastric cancer progression but have no independent prognostic relevance.

Author Correction: Tumour-stroma ratio and 5-year mortality in gastric adenocarcinoma: a systematic review and meta-analysis.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Tumour-stroma ratio and 5-year mortality in gastric adenocarcinoma: a systematic review and meta-analysis.

Tumour-stroma ratio (TSR) is a novel potential prognostic factor in cancers and based on the proportions of stroma and tumour area. The prognostic value of TSR in gastric cancer is incompletely known. The aim of this study was to estimate prognostic significance of TSR in gastric adenocarcinoma. A search of PubMed (MEDLINE), Web of Science, EMBASE, Cochrane and Scopus databases was performed. A meta-analysis was conducted on five-year survival in gastric cancer patients using inverse variance random-effects methods. The literature search yielded 5329 potential titles, of which a total of seven studies were eligible. Results of six studies including a total of 1779 patients were pooled in the meta-analysis. Only 23 (1.3%) of the patients received neoadjuvant therapy. All six studies had a cut-off of 50% for the proportion of stroma when dividing the patients into low- and high stroma groups. Low TSR (high amount of stroma) was strongly associated with increased five-year mortality (hazard ratio 2.19, 95% CI 1.69-2.85). In conclusion, TSR is a strong prognostic factor in gastric cancer. It could be used to estimate prognosis of gastric cancer patients not receiving neoadjuvant chemotherapy. Further studies including patients receiving neoadjuvant therapy are recommended.

Histological assessment of stromal maturity as a prognostic factor in surgically treated gastric adenocarcinoma.

AIMS: Histological assessment of stromal maturity is a potential prognostic factor in colorectal cancer, but its applicability in gastric adenocarcinoma is completely unknown. The aim of this study was to evaluate the feasibility and prognostic significance of assessing stromal maturity in gastric adenocarcinoma. METHODS AND RESULTS: This study was conducted retrospectively in a cohort of 583 gastric adenocarcinoma patients treated surgically in Oulu University Hospital, Finland between 1983 and 2016. The original diagnostic slides were used for assessment of stromal maturity. Patients were divided into mature stroma and immature stroma groups, and stromal maturity was analysed in relation to 5-year and overall survival (OS). The primary outcome of the study was 5-year survival, and the secondary outcome was OS. The kappa-coefficient for interobserver agreement was 0.609. Patients with immature stroma had worse 5-year survival compared to patients with mature stroma [adjusted hazard ratio (HR) = 1.32, 95% confidence interval (CI) = 1.06-1.64]. Stromal maturity was significantly associated with 5-year survival in intestinal-type subgroup (adjusted HR = 0.63, 95% CI = 1.20-2.21), but not in the diffuse-type subgroup (adjusted HR = 1.21, 95% CI = 0.87-1.70). CONCLUSIONS: Stromal maturity is an independent prognostic factor in gastric adenocarcinoma, and it can be analysed with moderate reproducibility.

Tumor Budding and Prognosis in Gastric Adenocarcinoma.

Tumor budding has been associated with poor prognosis in several cancer types, but its significance in gastric cancer is unknown. The aim of this study was to assess the prognostic significance of tumor budding in gastric adenocarcinoma, and its main histologic types. Some 583 gastric adenocarcinoma patients who underwent surgery in Oulu University Hospital during the years 1983-2016 were included in this retrospective cohort study. Tumor budding was counted per 0.785 mm fields from the slides originally used for diagnostic purposes. Patients were divided into low-budding (<10 buds) and high-budding (≥10 buds) groups. Tumor budding was analyzed in relation to 5-year survival and overall survival. Cox regression was used to calculate hazard ratios (HR) with 95% confidence intervals (CI), adjusted for confounders. Determining tumor budding was difficult in diffuse-type cancer due to the uncohesive growth pattern of these tumors. Patients with high tumor budding had worse 5-year survival compared with patients with low tumor budding (adjusted HR, 1.55; 95% CI, 1.20-2.01). In intestinal-type adenocarcinomas, the high-budding group had significantly poorer 5-year survival compared with the low-budding group (adjusted HR, 1.57; 95% CI, 1.14-2.15). There were no differences in 5-year survival between the budding groups in the diffuse type adenocarcinoma. In conclusion, high tumor budding is an independent prognostic factor in gastric adenocarcinoma, but its value is limited to the intestinal type of gastric adenocarcinoma. In diffuse type gastric adenocarcinoma, the assessment of tumor budding is hardly feasible, and it does not have prognostic relevance.

Tumour-stroma ratio and prognosis in gastric adenocarcinoma.

BACKGROUND: Tumour microenvironment, including tumour-stroma ratio (TSR), might help identifying high-risk cancer patients. However, the significance of TSR in gastric cancer is unclear, especially in the intestinal and diffuse subtypes. The aim of this study was to investigate the tumour-stroma ratio in gastric adenocarcinoma, and its intestinal and diffuse histological subtypes, in relation to prognosis. METHODS: Five hundred and eighty-three gastric adenocarcinoma patients who underwent surgery in Oulu University hospital during years 1983-2016 were included in this retrospective cohort study. TSR was analysed from the slides that were originally used for diagnostic purposes. Patients were divided into stroma-poor (≤50% stroma) and stroma-rich (>50% stroma) groups and TSR was analysed in relation to 5-year mortality and overall mortality. RESULTS: Patients with stroma-rich tumours had worse 5-year prognosis (HR 1.80, 95% CI 1.41-2.28) compared to stroma-poor tumours. Stratified analysis showed that stroma-rich tumours had worse 5-year prognosis in both intestinal (HR 1.68, 95% CI 1.24-2.27) and diffuse histological types (HR 2.09, 95% CI 1.35-3.23) compared to stroma-poor tumours, respectively. CONCLUSIONS: High proportion of stroma is an independent prognostic factor in both intestinal and diffuse histological subtypes of gastric adenocarcinoma.