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Limited studies investigated clinicopathological and prognostic significance of histologic and molecular subgroups of gastric cancer concurrently. We retrospectively enrolled 1,248 patients with gastric cancer who received radical gastrectomy with lymphadenectomy and classified these cases into the Epstein–Barr virus (EBV)‐associated and microsatellite instability (MSI)‐associated subtypes by EBV‐encoded small RNA in situ hybridization and immunohistochemical stains for DNA mismatch repair proteins, respectively. The remaining cases were categorized as the Lauren intestinal and diffuse/mixed subtypes. The clinicopathological and prognostic significance of the subtypes was examined by statistical analysis. In total, 65 (5.2%), 116 (9.3%), 496 (39.7%), 431 (34.5%) and 140 (11.2%) cases were identified as EBV‐associated, MSI‐associated, intestinal, diffuse and mixed subtypes, respectively. The EBV‐associated, MSI‐associated, intestinal and diffuse/mixed subtypes exhibited distinctive clinicopathological characteristics, including differences in age, gender, stump cancer, gastric location, tumor size, TNM stage, margin involvement, lymphatic/perineural invasion, HER2 status and recurrence pattern. The log‐rank test showed survival discrimination (p < 0.001), and the multivariate analysis identified EBV‐associated and MSI‐associated cases demonstrated better outcomes than the diffuse/mixed subtype (EBV, HR 0.464, 95% CI 0.296–0.727, p = 0.001; MSI, HR 0.590, 95% CI 0.407–0.856, p = 0.005). EBV‐associated lymphoepithelioma‐like carcinoma cases had the most favorable outcome (HR 0.138, 95% CI 0.033–0.565, p = 0.006). In different clinical groups, the subtypes exhibited survival discrepancies. The EBV‐associated and diffuse/mixed cases exhibited more favorable response to chemotherapy. In conclusion, this combined classification, in parallel with the molecular subtypes specified in the Cancer Genome Atlas study, has implications for the clinical management of gastric cancer.

Pathologic diagnosis of nasopharyngeal carcinoma (NPC) can be challenging since most cases are nonkeratinizing carcinoma with little differentiation and many admixed lymphocytes. Our aim was to evaluate the possibility to identify NPC in nasopharyngeal biopsies using deep learning. A total of 726 nasopharyngeal biopsies were included. Among them, 100 cases were randomly selected as the testing set, 20 cases as the validation set, and all other 606 cases as the training set. All three datasets had equal numbers of NPC cases and benign cases. Manual annotation was performed. Cropped square image patches of 256 × 256 pixels were used for patch-level training, validation, and testing. The final patch-level algorithm effectively identified NPC patches, with an area under the receiver operator characteristic curve (AUC) of 0.9900. Using gradient-weighted class activation mapping, we demonstrated that the identification of NPC patches was based on morphologic features of tumor cells. At the second stage, whole-slide images were sequentially cropped into patches, inferred with the patch-level algorithm, and reconstructed into images with a smaller size for training, validation, and testing. Finally, the AUC was 0.9848 for slide-level identification of NPC. Our result shows for the first time that deep learning algorithms can identify NPC.

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The prognostic value of programmed death-ligand 1 (PD-L1) expression in nasopharyngeal carcinoma (NPC) is controversial, with previous studies showing conflicting results. Most NPCs in endemic areas are Epstein-Barr virus (EBV)-positive. Our aim was to evaluate the clinical significance of PD-L1 expression in EBV-positive NPC. We retrospectively analyzed PD-L1 expression on tumor cells (TCs) and immune cells (ICs) by immunohistochemistry in 208 EBV-positive NPC patients who underwent radiotherapy (203 with concurrent chemotherapy). The percentages of TCs and ICs expressing PD-L1 were evaluated respectively. There was a strong correlation between local recurrence and low PD-L1 expression on ICs (p = 0.0012), TCs (p = 0.013) or both (p = 0.000044), whereas all clinical parameters had no influence on local recurrence. Using multivariate analysis, low PD-L1 expression on ICs was an independent adverse prognostic factor (p = 0.0080; HR = 1.88; 95% CI = 1.18–3.00) for disease-free survival. High PD-L1 expression on both ICs and TCs was an independent favorable prognostic factor (p = 0.022; HR = 0.46; 95% CI = 0.24–0.89) for overall survival. We show for the first time that low PD-L1 expression on ICs and TCs strongly correlates with local recurrence in EBV-positive NPC patients after radiation-based therapy. A simple immunohistochemical study for PD-L1 can identify patients prone to local recurrence, and such patients might benefit from more aggressive treatment in future clinical trials.

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Aims In this study, we examine the clinicopathological and molecular features of gastric cancer (GC) with SMARCA4 alterations. Methods and results We screened SMARCA4 alterations using immunohistochemistry on 1199 surgically resected GCs with information on Epstein–Barr virus (EBV), microsatellite instability (MSI) and other SWI/SNF subunits. SMARCA4, SMARCA2 and ARID1A mutations were investigated by targeted sequencing. The clinicopathological significance was determined by statistical analysis. Twenty‐seven cases (2%) with altered SMARCA4 expression were identified, exhibiting completely lost (six), reduced (nine) or heterogeneous (12) patterns. Frequent concomitant alterations of other SWI/SNF subunits were noted with an unusual discordant spatial heterogeneity. In comparison with SMARCA4‐retained GCs, SMARCA4‐lost GCs were observed more frequently in the non‐EBV/MSI subgroup (five of six) and reduced or heterogeneous SMARCA4 expression mainly occurred in EBV‐ or MSI‐associated cases (six of nine and six of 12, respectively; P < 0.001). Histologically, SMARCA4‐altered GC, irrespective of expression pattern, demonstrated divergent histomorphology, spanning tubular, poorly cohesive or mixed, neuroendocrine to solid and undifferentiated carcinoma, with a predilection to the latter two (P < 0.001). De‐differentiation‐like transition and rhabdoid features were noted in a minority of cases. For overall survival, altered SMARCA4 expression was an unfavourable prognostic factor in stage III, EBV‐associated GC and non‐EBV/MSI intestinal subtype (P ≤ 0.001). SMARCA4 or ARID1A mutations were detected mainly in SMARCA4‐lost or reduced GC, respectively. Conclusions SMARCA4‐altered GCs are rare and have intratumoral heterogeneity, histomorphological diversity, conditional prognostic significance and various genetic drivers. SMARCA4‐lost GC may represent a genuine SMARCA4‐deficient neoplasm, but most SMARCA4‐reduced/heterogeneous cases are secondary to ARID1A collapse or associated with different genotypes.

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