Tropomyosin receptor kinase protein expression in Thai cholangiocarcinoma: Clinicopathological correlation, expression pattern, and prognosis

Tropomyosin receptor kinase (TRK) gene fusion was found in association with many tumors and could be a target of treatment. Immunohistochemistry (IHC) expression of TRK is widely used to screening this alternation. To investigate the expression of TRK protein detected by IHC in Thai cholangiocarcinoma (CCA) whereas the high endemic area of liver fluke infection and correlate with clinicopathological and survival data. Retrospective study of CCA patients who diagnosed from January 2011 to December 2015. The TRK IHC was performed on paraffin-embedded tissues. A total of 85 CCA patients were enrolled. The mean age of the patients was 59 y (range; 35–79). Tumors were situated at intrahepatic (42 cases, 49.4 %), perihilar (41 cases, 48.2 %) and extrahepatic (2 cases, 2.4 %). The TRK IHC was expressed in 26 cases (31 %) and most of them (25 cases, 96.2 %) showed focal cytoplasmic expression with weak intensity. TRK IHC expression was not correlated with clinicopathological findings. Nevertheless, the median survival time of the TRK IHC positive and negative groups were 1.88-year and 1.30-year, respectively ( p  = 0.041) with the hazard ratio of 0.564 ( p  = 0.039, 95%CI 0.328–0.971). In Thai CCA, TRK IHC was detected about 1/3 of the patients and most expressed focally in the cytoplasm with weak staining. TRK expression showed better overall survival and was an independent prognostic factor. As the screening assays, the TRK IHC is wildly available with rapid, and high sensitivity but the confirmatory testing is necessary in tumors with low incidence of NTRK gene fusion.