Regional reporting of the incidence of Anaplastic Lymphoma Kinase mutation in 379 non-small-cell lung cancer patients from Kolkata: Using immunohistochemistry as the diagnostic modality in a significant subset

CONTEXT: Regional epidemiology of anaplastic lymphoma kinase (ALK) mutation in non-small-cell lung cancer (NSCLC) is an unmet need in India, and so is the knowledge of its incidence based on immunohistochemistry (IHC). AIMS: Reporting the incidence of ALK mutation in NSCLC from Kolkata, incorporating IHC as the diagnostic modality in a considerable subset of patients. SUBJECTS AND METHODS: It is a retrospective observational study done on NSCLC patients with adenocarcinoma histology, unselected by epidermal growth factor receptor, whose samples were tested for ALK mutation status between March 1, 2013, and March 15, 2017. The study involved all cancer facilities in Kolkata, except Tata Medical Centre. Up to June 2015, the tests were done by fluorescence in situ hybridization (FISH) and from July 2015 to the end, tests were done using IHC, as per the standard testing guidelines existing during the respective time periods. Results were documented in a de-identified manner to analyze the incidence of ALK mutations. RESULTS: A total of 379 patients was tested for ALK mutations. March 2013 to June 2015, 200 (52.77%) patients were tested by FISH, 17 (8.5%) samples were unreportable and 4 patients [(2.19%) 4/183] tested positive for ALK mutations. From July 2015 to March 2017, 179 (47.22%) patients were tested by IHC, 9 (5.02%) samples were unreportable, and 10 patients [(5.88%) 10/170] tested positive for ALK mutations. Overall, 26 (6.8%) samples were unreportable and 14 [(3.9%) 14/353] patients tested positive for ALK mutations. CONCLUSIONS: The overall incidence of ALK mutation positive NSCLC in Kolkata is 3.9%. The incidence by IHC is 5.88% and by FISH is 2.19%, in the subset of patients tested by these two modalities respectively.