Cytoplasmic TrkA Expression as a Screen for Detecting NTRK1 Fusions in Colorectal Cancer.

NTRK1 gene fusions, the targets of multikinase inhibitors, are promising therapeutic targets for colorectal cancer (CRC). However, screening methods for detecting NTRK1 gene fusions in CRC tissues have not been reported. In this study, we investigated the potential use of immunohistochemistry (IHC) for detecting NTRK1 gene fusions. We performed and compared IHC with fluorescence in situ hybridization (FISH) in 80 CRC patients. TrkA immunostaining was observed to be both membranous and cytoplasmic and was scored semiquantitatively using staining intensity and proportions. The tumors were observed to be NTRK1 gene fusion-positive when ≥20 out of 100 nuclei in FISH. A significant correlation between the IHC and FISH results for determination of the NTRK1 gene fusions was observed. We measured the cytoplasmic TrkA expression, which showed an area under the receiver operating characteristic (ROC) curve of 0.926 (range: 0.864-0.987, 95% CI, P=.001). By choosing 4.5 (sum of the intensity and proportion scores of cytoplasmic TrkA expression) as the cut-off value for the positive and negative NTRK1 gene fusion groups, the sensitivity and specificity for predicting lymph node metastasis were 100 and 83.8%, respectively (P=.001). Specifically, high cytoplasmic TrkA expression (sum of intensity and proportion scores >4) was associated with the presence of NTRK1 gene fusions (P<.0001, r=0.528). Taken together, our data showed that IHC for TrkA can be used as an efficient screening method for detecting NTRK1 gene fusions in CRC.

Negative pathology after endoscopic resection of gastric epithelial neoplasms: importance of pit dysplasia.

BACKGROUND/AIMS: Endoscopic resection (ER) is a well-established treatment modality for gastric epithelial neoplasm. However, there is a discrepancy between forceps biopsy and ER specimen pathology, including a negative pathologic diagnosis (NPD) after ER. It has been suggested that pit dysplasia (PD) is a subtype of gastric dysplasia, and the aim of this study was to assess the significance of PD in cases with NPD after ER for early gastric neoplasms. METHODS: After ER, 29 NPD lesions that had an associated pretreatment forceps biopsy specimen, were correctly targeted during ER, and had no cautery artifact on the resected specimen were included in this study. RESULTS: Sixteen lesions showed PD and 13 had no neoplastic pathology. The initial pretreatment forceps biopsy diagnoses of 29 NPD lesions were low-grade dysplasia (LGD) in 17 lesions, high-grade dysplasia (HGD) in seven lesions, and adenocarcinoma in five lesions, which after review were revised to PD in 19 lesions, LGD in four lesions, adenocarcinoma in two lesions, and no neoplastic pathology in four lesions. Overall, nine lesions (31%) were small enough to be removed by forceps biopsy, four NPD lesions (14%) were initially misinterpreted as neoplastic lesions, and 16 PD lesions (55%) were misinterpreted as NPD lesions on ER slides. CONCLUSIONS: Approximately half of the lesions initially diagnosed as LGD or HGD were subsequently classified as PD. Therefore, including PD as a subtype of gastric dysplasia could reduce the diagnostic discrepancy between initial forceps biopsy and ER specimens.

Venous Invasion in Colorectal Cancer: Impact of Morphologic Findings on Detection Rate.

PURPOSE: Venous invasion (VI) is widely accepted as a poor prognostic factor in colorectal cancer (CRC), and is indicated as a high-risk factor determining the use of adjuvant chemotherapy in CRC. However, there is marked interobserver and intraobserver variability in VI identification and marked variability in the real prevalence of VI in CRC. MATERIALS AND METHODS: We investigated the detection rate of VI in 93 consecutive cases of T3 or T4 CRC based on the following: original pathology report, review of hematoxylin and eosin (H&E) slides with attention to the "protruding tongue" and "orphan arteriole" signs, and elastic stain as the gold standard. RESULTS: Overall, the detection rate of VI was significantly increased as follows: 14/93 (15.1%) in the original pathology report, 38/93 (40.9%) in review of H&E slides with attention to the "protruding tongue" and "orphan arteriole" signs, and 45/93 (48.4%) using elastic stain. VI detection based on morphologic features showed 77.8% sensitivity and 91.1% specificity and showed a linear correlation (Spearman correlation coefficient, 0.727; p < 0.001) with VI detected by elastic stain. In addition, improved agreement between detection methods (detection on the basis of morphologic features, κ=0.719 vs. original pathology report, κ=0.318) was observed using kappa statistics. CONCLUSION: Slide review with special attention to the "protruding tongue" and "orphan arteriole" signs could be used for better identification of VI in CRC in routine surgical practice.