Browsing by Author "Kannangara, D.K.S."

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    Could quantitative real-time polymerase chain reaction assay serve as an alternative test method to evaluate human epidermal growth factor receptor 2 status of gastric carcinoma in the South Asian setting?
    (Indian Society of Gastroenterology/Springer India, 2019) Kannangara, D.K.S.; Lokuhetty, M.D.S.; Subasinghe, D.; Gunawardene, Y.I.N.S.; Dassanayake, R.S.
    BACKGROUND:Human epidermal growth factor receptor 2 (HER2) protein overexpression and/or HER2 gene amplification are/is linked to a dismal outcome of gastric carcinoma (GCa). Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) are key methods to identify patients for HER2 targeted therapy. Drawbacks of both the methods warrant novel tests. Hence, we evaluated the value of quantitative real-time polymerase chain reaction (qPCR) as an alternative test method, relative to IHC to detect HER2 status of GCa and to find relationship between these results with demographic/clinicopathological data.METHOD:Twenty GCa patients with known IHC HER2 scores were evaluated. qPCR was performed for the HER2 gene and amyloid precursor protein (reference gene) in formalin-fixed paraffin-embedded GCa tissue. Cycle threshold values (Ct) were analyzed using the Pfaffl method to detect HER2 gene amplification.RESULTS:HER2 positivity rates by IHC and qPCR were 20% and 35%, respectively. The sensitivity and specificity of qPCR were 67% and 76%, respectively, relative to IHC. qPCR results were reproducible. The diagnostic consistency between IHC and qPCR (κ = 0.146) was slightly agreeable (0.01 < k < 0.20), with a 65% concordance. Based on McNemar's test, there was no significant difference between the results of the two tests. IHC HER2 protein expression had relationship with the tumor (TNM) stage and Lauren histological type (p < 0.05). Positive HER2 gene expression by qPCR showed relationship with depth of invasion, lymph node involvement, and degree of differentiation (p < 0.05).CONCLUSION:Cost-effective qPCR could serve as an alternative test method for detection of HER2 status of GCa. Both HER2 overexpression by IHC and gene amplification by qPCR are associated with adverse clinicopathological features
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    Development of a quantitative PCR assay to evaluate HER2 status of Gastric carcinoma in a cohort of Sri Lankan patients
    (Sri Lanka Medical Association, 2016) Kannangara, D.K.S.; Subasinghe, D.; Lokuhetti, M.D.S.; Dassanayake, R.S.; Gunawardene, Y.I.N.S.
    INTRODUCTION AND OBJECTIVES: Human epidermal growth factor receptor2(HER2) protein overexpression and/or HER2gene amplification is linked to dismal outcome of Gastric carcinoma(GCa). Immunohistochemistry(IHC) and fluorescence in situ hybridization(FISH) are key-methods to identify patients for HER2 targeted therapy. Drawbacks of both methods warrant novel tests. The study aimed to determine whether quantitative Polymerase Chain Reaction (qPCR) could serve as a supplementary-method to evaluate HER2 status of GCa in a cohort of Sri Lankan patients and investigate correlation between HER2 assessed by different methods and clinic-pathological features. METHOD: Twenty GCa-patients with known IHC-HER2 scores were evaluated. qPCR was performed for HER2gene and Ameloid precursor protein (reference gene) in Formalin fixed paraffin embedded GCa tissue. Threshold values(Ct) were analyzed using Pfaffl-method to detect HER2gene amplification. RESULTS: HER2positivity by IHC(protein) and qPCR(gene) were 20% and 35% respectively. Sensitivity and specificity of qPCR was 67% and 76% respectively and results were reproducible. HER2protein positivity was correlated with Tumour TNM-stage and Lauren-histological types(P<0.05). Positive expression of HER2gene was correlated with depth of tumour invasion, differentiation and Lymph node-status(P<0.05). Diagnostic consistency between IHC and qPCR(κ=0.146) was slightly agreeable(0.01