Transformer-based biomarker prediction from colorectal cancer histology: A large-scale multicentric study.

Deep learning (DL) can accelerate the prediction of prognostic biomarkers from routine pathology slides in colorectal cancer (CRC). However, current approaches rely on convolutional neural networks (CNNs) and have mostly been validated on small patient cohorts. Here, we develop a new transformer-based pipeline for end-to-end biomarker prediction from pathology slides by combining a pre-trained transformer encoder with a transformer network for patch aggregation. Our transformer-based approach substantially improves the performance, generalizability, data efficiency, and interpretability as compared with current state-of-the-art algorithms. After training and evaluating on a large multicenter cohort of over 13,000 patients from 16 colorectal cancer cohorts, we achieve a sensitivity of 0.99 with a negative predictive value of over 0.99 for prediction of microsatellite instability (MSI) on surgical resection specimens. We demonstrate that resection specimen-only training reaches clinical-grade performance on endoscopic biopsy tissue, solving a long-standing diagnostic problem.

Frequent Coamplification of Receptor Tyrosine Kinase and Downstream Signaling Genes in Japanese Primary Gastric Cancer and Conversion in Matched Lymph Node Metastasis.

OBJECTIVE: To establish the gene copy number status of receptor tyrosine kinase (RTK) and downstream signaling (DSS) genes genes in primary gastric cancer (primGC) and matched lymph node metastases (LNmet). BACKGROUND: Evidence suggests that coamplification between RTKs and DSSs and conversion between primGC and LNmet are associated with resistance to targeted therapy. METHODS: DNA from 237 Japanese primGC and 103 matched LNmet was analyzed using a newly developed multiplex ligation-dependent probe amplification (MLPA) probemix to investigate RTK (EGFR, HER2, FGFR2, and MET) and DSS (PIK3CA, KRAS, MYC, and CCNE1) gene copy number status. Results were compared between primGC and LNmet and related to clinicopathological data including survival. RESULTS: A total of 150 (63%) primGC had either RTK or DSS amplification. DSS coamplification was more frequent than RTK coamplification in primGC and LNmets. Moreover, 70 (30%) GC showed a disconcordant RTK and/or DSS gene copy number status between primGC and LNmet, most common was negative conversion for DSS genes (n=40 GC). The presence of RTK amplification in primGC was related to poorer survival in univariate analysis (P=0.04). CONCLUSIONS: This is the first and most comprehensive study in gastric cancer investigating the concordance between gene copy number status of targetable RTKs and downstream signaling oncogenes in primGC and LNmets. Future studies need to establish whether the relative high frequency of RTK and DSS coamplification and/or the relative high rate of negative conversion in LNmet can potentially explain recent failures of RTK targeted therapy in gastric cancer patients.

Biopsy proportion of tumour predicts pathological tumour response and benefit from chemotherapy in resectable oesophageal carcinoma: results from the UK MRC OE02 trial.

BACKGROUND: Neoadjuvant chemotherapy followed by surgery is the standard of care for UK patients with locally advanced resectable oesophageal carcinoma (OeC). However, not all patients benefit from multimodal treatment and there is a clinical need for biomarkers which can identify chemotherapy responders. This study investigated whether the proportion of tumour cells per tumour area (PoT) measured in the pre-treatment biopsy predicts chemotherapy benefit for OeC patients. PATIENTS AND METHODS: PoT was quantified using digitized haematoxylin/eosin stained pre-treatment biopsy slides from 281 OeC patients from the UK MRC OE02 trial (141 treated by surgery alone (S); 140 treated by 5-fluorouracil/cisplatin followed by surgery (CS)). The relationship between PoT and clinicopathological data including tumour regression grade (TRG), overall survival and treatment interaction was investigated. RESULTS: PoT was associated with chemotherapy benefit in a non-linear fashion (test for interaction, P=0.006). Only patients with a biopsy PoT between 40% and 70% received a significant survival benefit from neoadjuvant chemotherapy (N=129; HR (95%CI):1.94 (1.39-2.71), unlike those with lower or higher PoT (PoT<40%, N=39, HR:1.25 (0.66-2.35); PoT>70% (N=28, HR:0.65 (0.36-1.18)). High pre-treatment PoT was related to lack of primary tumour regression (TRG 4 or 5), P=0.0402. CONCLUSIONS: This is the first study to identify in a representative subgroup of OeC patients from a large randomized phase III trial that the proportion of tumour in the pre-chemotherapy biopsy predicts benefit from chemotherapy and may be a clinically useful biomarker for patient treatment stratification.Proportion of tumour is a novel biomarker which can be measured in the pre-treatment diagnostic biopsy and which may enable the identification of chemotherapy responders and non-responders among patients with oesophageal carcinoma. Proportion of tumour could easily become part of the routine reporting of oesophageal cancer biopsies and may aid in managing patients with borderline resectable cancer.

Exercise increases the frequency of circulating hematopoietic progenitor cells, but reduces hematopoietic colony-forming capacity.

Circulating hematopoietic progenitor cells (CPCs) may be triggered by physical exercise and/or normobaric hypoxia from the bone marrow. The aim of the study was to investigate the influence of physical exercise and normobaric hypoxia on CPC number and functionality in the peripheral blood as well as the involvement of oxidative stress parameters as possibly active agents. Ten healthy male subjects (25.3±4.4 years) underwent a standardized cycle incremental exercise test protocol (40 W+20 W/min) under either normoxic (FiO2 ∼0.21) or hypoxic conditions (FiO2<0.15, equals 3,500 m, 3 h xposure) within a time span of at least 1 week. Blood was drawn from the cubital vein before and 10, 30, 60, and 120 min after exercise. The number of CPCs in the peripheral blood was analyzed by flow cytometry (CD34/CD45-positive cells). The functionality of cells present was addressed by secondary colony-forming unit-granulocyte macrophage (CFU-GM) assays. To determine a possible correlation between the mobilization of CPCs and reactive oxygen species, parameters for oxidative stress such as malondialdehyde (MDA) and myeloperoxidase (MPO) were obtained. Data showed a significant increase of CPC release under normoxic as well as hypoxic conditions after 10 min of recovery (P<0.01). Most interestingly, although CD34+/CD45dim cells increased in number, the proliferative capacity of CPCs decreased significantly 10 min after cessation of exercise (P<0.05). A positive correlation between CPCs and MDA/MPO levels turned out to be significant for both normoxic and hypoxic conditions (P<0.05/P<0.01). Hypoxia did not provoke an additional effect. Although the CPC frequency increased, the functionality of CPCs decreased significantly after exercise, possibly due to the influence of increased oxidative stress levels.

Low molecular weight heat shock protein HSP27 is a prognostic indicator in rectal cancer but not colon cancer.

OBJECTIVE: There are currently no biomarkers in routine clinical use for determining prognosis in rectal cancer. In a preliminary proteomic study, variation in the levels of heat shock protein 27 (HSP27) in colorectal cancer samples was observed. The expression of HSP27 in a cohort of 404 patients with colorectal cancer with a predominantly poor prognosis was characterised and an investigation was undertaken of whether the differences were related to clinical outcome. HSP27 levels in diagnostic rectal biopsies were compared with matched surgical samples to determine whether changes in expression occurred in the time between biopsy and surgery and to investigate whether preoperative radiotherapy affected expression. Finally, the relationship between HSP27 expression and outcome was examined in an independent cohort of 315 patients with a predominantly good prognosis. METHODS: HSP27 levels were determined using combined two-dimensional gel electrophoresis and tandem mass spectrometry (12 cases) and by immunohistochemistry using tissue microarrays of colorectal cancers sampled at surgery and 80 diagnostic rectal biopsies. RESULTS: HSP27 overexpression was strongly associated with poor cancer-specific survival in rectal cancer (n=205, p=0.0063) but not colon cancer (n=199, p=0.7385) in the cohort with a poor prognosis. Multivariate Cox regression confirmed nodal metastases (p=0.0001) and HSP27 expression (p=0.0233) as independent markers of survival in rectal cancer. HSP27 levels remained unchanged in the majority of cases (65/80, 81%) between diagnostic biopsies and matched surgical samples, regardless of whether patients had undergone preoperative radiotherapy. In the cohort with a good prognosis the association between HSP27 and survival was not observed in patients with either rectal (n=115; p=0.308) or colon cancer (n=200; p=0.713). CONCLUSION: In a large cohort of patients with a poor prognosis, HSP27 is an independent marker of poor outcome in rectal cancer; its expression is not altered by neoadjuvant radiotherapy. This finding requires validation in an independent similar cohort of patients with rectal cancer. HSP27 levels merit evaluation as a stratification factor for treatment of rectal cancer.

Expression of DNA double-strand break repair proteins ATM and BRCA1 predicts survival in colorectal cancer.

PURPOSE: The double-strand break (DSB) is the major DNA lesion leading to chromosomal aberrations and faithful repair is crucial for maintaining genomic instability. Very little is known about the expression of DNA DSB repair proteins in colorectal cancer. To address this issue, we examined the expression pattern of DSB repair key proteins ATM, BRCA1, BRCA2, Ku70, and Ku80 and their putative role in patients survival in a large series of colorectal cancer. EXPERIMENTAL DESIGN: 342 sporadic colorectal cancer were subjected to immunohistochemistry by using specific antibodies for the various proteins investigated. Staining results were compared with clinicopathologic data, patient survival, as well as expression of mismatch repair proteins MLH1 and MSH2. RESULTS: The expression pattern of both ATM and BRCA1 predicted survival in all colorectal cancer patients as well as in the small subgroup of patients that received adjuvant therapy. Low expression of ATM and BRCA1 was associated with loss of MLH1 or MSH2 expression. CONCLUSIONS: This is the first study to show a relationship between the expression of DNA DSB repair proteins ATM and BRCA1 and survival in colorectal cancer patients. Studies in tumors from large randomized trials are now necessary to validate our pilot data and establish the clinical usefulness of the immunohistochemical assay in predicting response to a particular adjuvant therapy regimen. Furthermore, our results indicate a possible link between expression of DNA mismatch repair and DNA DSB repair proteins in sporadic colorectal cancer, which warrants further investigation.

A new method for optimizing multiplex DNA microsatellite analysis in low quality archival specimens.

BACKGROUND: Testing microsatellite instability seems to be a useful tool for the initial screening of putative non-polyposis colorectal cancer (HNPCC), preceding analysis of germ-line mutations of DNA mismatch repair genes. However, diagnosis of microsatellite instability becomes complicated when highly-damaged DNA from formalin-fixed paraffin-embedded tissue specimens has to be investigated. MATERIALS AND METHODS: A new methodical approach was established based on special multiplex PCR regimes (e.g., on touch-up cycling conditions), allowing both sufficient, as well as specific, amplification of the Bethesda reference panel loci with low quality DNA as template. RESULTS: By applying our new method, microsatellite instability could be analyzed successfully in 75 out of 84 investigated tumors (89%), whereas, by using standard PCR protocols, microsatellite analysis failed in 36% of the investigated cases. CONCLUSION: Our new methodical approach should be recommended for the use of archival material since it allows an efficient and accurate amplification of the Bethesda marker fragments and is less dependent on the DNA quality.

EphB2 is a prognostic factor in colorectal cancer.

A receptor tyrosine kinase for ephrin ligands, EphB2 is expressed in colorectal cancer and has been proposed as a target for immunoconjugate therapy. The aim of this study was to perform a detailed histologic analysis of EphB2 expression in normal and neoplastic colorectal tissues. In addition, we sought to evaluate EphB2 expression as a prognostic factor in colorectal cancer. Expression of EphB2 was examined in normal colon (n = 28), colorectal cell lines (n = 20), colorectal adenomas (n = 148), primary cancers (n = 28), and metastases (n = 39) using immunohistochemistry. In addition, a series of primary cancers and matched normal (n = 342) with outcome data were profiled in tissue microarrays. The intensity of EphB2 expression was assessed in the entire series by immunohistochemistry, and in a subset by in situ hybridization. Overall survival and recurrence-free survival were correlated with EphB2 protein expression in retrospective subset analyses. Epithelial EphB2 expression was shown at all stages of colorectal tumorigenesis, including the base of all normal crypts, 77% of adenomas, 82% of primary cancers, and 64% of metastases. Although homogeneous expression was observed in adenomas, the pattern of staining was focal (mean 25%) in most malignant lesions. Patients whose tumor stained 2+ for EphB2 expression (versus 0/1+) exhibited significantly prolonged overall survival: mean duration of survival, 2,514 versus 1,044 days; hazard ratio, 0.45; 95% confidence interval, 0.18 to 0.95 (P = 0.035). In summary, EphB2 is expressed in normal crypts, colorectal adenomas, primary cancers, and metastases. High levels of EphB2 expression are associated with a longer mean duration of survival in colorectal cancer.

Prognostic value of cyclin B1 protein expression in colorectal cancer.

We used immunohistochemical analysis to study the expression and prognostic impact of cyclin B1, a key molecule for G2-M phase transition during the cell cycle, in a series of 342 curatively resected colorectal carcinomas. In 269 tumors (78.7%), high expression of cyclin B1 in more than 10% of tumor cells was observed, but there was no association between cyclin B1 expression and histopathologic tumor features. Univariate analysis revealed no impact on disease-free and overall survival. Multivariate analysis revealed pT and pN categories, extramural blood vessel invasion, and low-grade tumor cell differentiation as independent prognostic predictors for overall survival, and pT and pN categories and tumor site for disease-free survival. According to our results, high expression of cyclin B1 is a frequent and early event in colorectal carcinomas. However, cyclin B1 expression is neither a predictor of prognosis in patients with colorectal cancer nor a suitable tool for identifying subgroups of patients at higher risk for disease recurrence.

Decreased Fas expression in advanced-stage bladder cancer is not related to p53 status.

OBJECTIVES: The Fas-Fas ligand system is an important regulator of apoptosis and is involved in tumor development. Invasive cancers downregulate Fas expression to evade antitumor immune responses. Fas is a transcriptional target of p53, which is often mutated in bladder cancers. Therefore, Fas expression and its relation to p53 mutation was investigated. METHODS: Expression of Fas protein and p53 status was studied by immunohistochemistry in 83 bladder cancer specimens. In addition, mRNA levels for soluble (decoy) and membrane-bound forms of Fas were compared between 10 bladder cancer cell lines and primary uroepithelial cells by quantitative TaqMan polymerase chain reaction. Mutational analysis of the death domain of the Fas gene was performed in all cell lines. RESULTS: Organ-confined tumors maintained specific Fas staining at the cell membrane and often also in the cytoplasm. In higher stage carcinomas, Fas expression became restricted to a smaller fraction of cells or was lacking entirely. The correlation of Fas staining with tumor stage was highly significant but no correlation to tumor grade or survival was found. Furthermore, no statistically significant relationship was observed with either the presence or lack of mutated p53 accumulation. Membrane-bound Fas mRNA was decreased in most, and soluble Fas was increased in all transitional cell carcinoma lines compared with primary uroepithelial cells. No mutations in the death domain were detected. CONCLUSIONS: Fas downregulation occurring in advanced bladder cancer is unrelated to p53 mutations. The results of immunohistochemistry and mRNA studies of soluble and membrane-bound Fas in transitional cell carcinoma lines support the hypothesis of immune evasion in advanced bladder cancer.

Expression of BUB1 protein in gastric cancer correlates with the histological subtype, but not with DNA ploidy or microsatellite instability.

During mitosis, the spindle checkpoint delays the onset of anaphase until all chromosomes have attached properly to the mitotic spindle, preventing chromosome missegregation. BUB (budding uninhibited by benzimidazole) 1 is one of the key components of this checkpoint. BUB1 mutations are rare in cancer tissues and no mutations have been identified in gastric cancer. In mice, immunodepletion of BUB1 abolished the spindle checkpoint. Thus, aberrant expression of BUB1 protein could impair mitotic checkpoint function, resulting in aneuploidy, a common phenomenon in gastric cancer. In the present study, an antibody was generated against BUB1 and its expression was studied in gastric cancer tissue sections (n = 80) by immunohistochemistry. Nuclear BUB1 expression was found in all gastric cancer cases. The proportion of tumour cells expressing BUB1 was significantly greater in diffuse-type than in intestinal-type gastric carcinoma (p < 0.001). No correlation was found between BUB1 expression and deoxyribonucleic acid (DNA) ploidy, microsatellite instability or any other histopathological parameters investigated. To the authors' knowledge, this is the first study of BUB1 protein expression in gastric cancer tissues. Different BUB1 protein expression levels in intestinal- and diffuse-type gastric cancer may provide further evidence of a potential link between different genetic pathways and morphological phenotype in gastric carcinogenesis. However, further studies are needed to establish whether there is an association between BUB1 protein expression level and mitotic spindle checkpoint function in gastric cancer.

Chromosomal imbalance in esophageal squamous cell carcinoma: 3q gain correlates with tumor progression but not prognostic significance.

DNA copy number changes were analyzed by comparative genomic hybridization (CGH) in 53 esophageal squamous cell carcinomas (ESCC) to clarify the relationship between DNA sequence copy number aberrations and clinicopathological factors. Changes in DNA copy number were observed in all 53 ESCC patients. The average number of DNA copy number gains was 9.32 (range 1-23), most frequently located on chromosomes 3q, 5p, 8q, 11q and Xq in over 40% of tumors. Loss of DNA copy number was detected on 3p, 5q, 4p, 1p and Xp in over 20% of tumors. No statistically significant differences in the frequency of DNA copy number changes were observed. However, some loci showed correlation with clinicopathologic factors: 8q gain correlated with the pattern of tumor infiltration, 3q gain correlated with pT, 2p gain, 1p loss and 16p loss correlated with lymphatic invasion, and 3q gain correlated with clinical stage. Thus, in ESCC, gain of 3q is the only specific recurrent pattern of DNA aberration that correlates with clinicopathologic parameters, although no particular loci correlated with patient prognosis. Further CGH analysis may reveal new, recurrent genetic changes in ESCC affecting chromosomes sites that harbor genes known to participate in tumorigenesis and progression of several human malignant neoplasms.

Overexpression of the mitotic checkpoint genes BUB1, BUBR1, and BUB3 in gastric cancer--association with tumour cell proliferation.

The mitotic spindle assembly checkpoint modulates the timing of anaphase initiation in response to improper alignment of chromosomes at the metaphase plate. The BUB gene family encodes proteins which are part of a large multi-protein kinetochore complex and which are believed to be key components of the checkpoint regulatory pathway. Failure of this surveillance system can lead to genomic instability and could be responsible for the increased incidence of aneuploidy in gastric cancer. Since mutations of BUB genes have not been identified in gastric cancer to date, altered BUB expression levels may significantly impair mitotic checkpoint function. To explore this possibility, the expression levels of BUB1, BUBR1, and BUB3 were determined in 43 gastric carcinomas and corresponding normal gastric mucosa by reverse transcription-polymerase chain reaction (RT-PCR). Gene expression levels were compared with histopathological parameters and DNA ploidy, as well as with proliferative activity, measured by Ki-67 mRNA expression. To the authors' knowledge, this is the first study to investigate the expression levels of mitotic checkpoint genes together with DNA ploidy in gastric cancer. BUB1 was overexpressed in 84%, BUBR1 in 68%, and BUB3 in 79% of gastric cancers. This study also revealed that all three genes were simultaneously overexpressed in 61% of the tumours and that there was a statistically significant positive correlation between overexpression of BUB1, BUBR1 or BUB3 and Ki-67 expression (p < 0.001). Eighty-one per cent of the tumours were classified as aneuploid. However, no correlation was found between ploidy and BUB transcript expression levels. These results suggest that inactivation of the mitotic checkpoint genes BUB1, BUBR1, and BUB3 by epigenetic silencing does not seem to play a role in gastric carcinogenesis. The strong correlation of BUB expression level and tumour cell proliferation suggests that BUB overexpression is a proliferation-dependent phenomenon in gastric cancer. However, overexpression due to lack of normal BUB protein function or due to a yet unknown additional BUB function has to be considered.

Detection of disseminated cancer cells in rib marrow of patients with esophageal cancer.

In the present study, micrometastasis in the rib marrow of 24 patients with esophageal cancer was examined using RT-PCR. RT-PCR was done using primers corresponding to cytokeratin 18 (CK18), squamous cell carcinoma antigen (SCC), and carcinoembryonic antigen (CEA). In 18 cases, CK18 was also detected in the rib marrow. Only one patient exhibited CEA amplification in the rib marrow. No cases demonstrated SCC amplification as a marker of micrometastasis in the rib marrow. The information from micrometastasis detected in the rib marrow using RT-PCR is useful in deciding whether or not adjuvant therapy is necessary after surgery. However, combined analysis using plural markers should be required since sensitivity or specificity of each marker may vary. Further follow-up of the patients is necessary to clarify the clinical impact of micrometastasis in rib marrow.

FHIT expression and hypermethylation in esophageal squamous cell carcinoma.

The expression of the fragile histidine triad (FHIT) gene has been proposed to play an important role in early events of carcinogenesis and to be correlated with the progression or clinical outcomes of various cancers. Attention has focused recently on the regulation of FHIT expression, and loss of heterozygosity or hypermethylation of the CpG island in the promoter region has been suggested as clues to a possible mechanism. Methylation status and FHIT expression were investigated in the present study to clarify the clinicopathologic impact of FHIT in vivo. One hundred and five patients with esophageal cancer were admitted to the study. Cancer tissues were immunohistochemically stained for FHIT, and FHIT methylation status was examined in 36 patients by the methylation-specific polymerase chain reaction. FHIT methylation and expression were analyzed with respect to both clinicopathologic parameters and their interactions. Tissue specimens from 35 of the 105 patients (33.3%) stained positively for FHIT. In contrast, the CpG island in the FHIT promoter region was hypermethylated in 25 of the 36 (69.4%) analyzed cases of esophageal cancer. Hypermethylation was significantly correlated with the deletion of FHIT protein expression (P<0.001). FHIT hypermethylation was not associated with any clinicopathologic parameters. In contrast, deletion of FHIT expression significantly promoted tumor invasion (P<0.05) and lymphatic vessel invasion (P<0.01). Lymph node metastasis also appeared higher in the absence of FHIT protein expression, but the result was not significant (P=0.069). Patients with a preserved FHIT gene expression possibly exhibited an improved prognosis compared with those with deleted FHIT expression (P=0.093). Hypermethylation of the FHIT promoter region may be a mechanism for regulating FHIT expression. FHIT gene expression was closely correlated with cancer progression, as indicated by tumor invasion and lymphatic spread, and it may provide insight into the mechanism of progression of esophageal cancer.

DNA-PKcs expression in esophageal cancer as a predictor for chemoradiation therapeutic sensitivity.

BACKGROUND: It would be of considerable benefit to patients with esophageal cancer to be able to predict the effect of CRT before therapy, because critical side effects could be avoided and the therapeutic cost of CRT-resistant cases could be reduced. One of the biological parameters with the potential to indicate radioresponse is the DNA double-strand break repair enzyme DNA-PKcs. This study aims to clarify the correlation between DNA-PKcs expression and CRT effect. METHODS: Sixty-seven patients with progressive esophageal cancer treated with CRT were included in this study. The relationship between the expression of DNA-PKcs and the effect of CRT was examined by using immunohistochemistry. The relationships between DNA-PKcs expression, clinicopathologic parameters, and CRT effect were investigated statistically. RESULTS: A significant correlation was found between the expression of DNA-PKcs and the effect of CRT (P =.0149). The high-DNA-PKcs expression group showed greater therapeutic sensitivity than the low-expression group. Clinicopathologic factors had no relationship with DNA-PKcs expression or CRT effect. CONCLUSIONS: This study suggests that high expression of DNA-PKcs correlates with CRT effect. DNA-PKcs expression could, therefore, be useful for predicting the effect of CRT. In addition, these results may make it possible to plan therapy taking patients' quality of life into consideration.

Transforming growth factor beta type II receptor expression in gastric cancer: evidence for two independent subgroups.

Transforming growth factor beta type II receptor (TGFbeta-IIR) has been found to be altered in primary gastrointestinal carcinomas. So far relatively few facts are known about the expression of TGFbeta-IIR in primary gastric cancer. Therefore, in the present study, TGFbeta-IIR expression was analyzed in 130 primary gastric carcinomas and correlated with clinicopathological findings, the presence of a mutator phenotype, the mutational status of the TGFbeta-IIR polyadenine tract and survival. TGFbeta-IIR expression was analyzed immunohistochemically. Microsatellite instability was evaluated using a PCR-based assay and the polyadenine run inside the TGFbeta-IIR gene was sequenced. A complete loss of TGFbeta-IIR expression could be found in 55 (42.3%) of these carcinomas. Loss of TGFbeta-IIR expression was significantly correlated with diffuse-type carcinomas according to the Lauren classification as well as with signet ring cell carcinomas and a lower grade of differentiation. No correlation was found with the overall prognosis, the presence of a mutator phenotype, or a mutated TGFbeta-IIR. Thus, our data suggest the existence of a further definite subgroup of diffuse-type gastric carcinomas with altered TGFbeta-IIR expression, independent from a mutator phenotype with TGFbeta-IIR gene mutations. However, according to our results, in gastric cancer neither loss of TGFbeta-IIR expression nor mutations of the TGFbeta-IIR are of prognostic value.