June 6 (Reuters) - Novocure Ltd's <NVCR.O> experimental device to treat a type of lung cancer helped in extending overall survival among patients in a late-stage study, but concerns around its commercial success sent the medical device maker's shares down more than 34% on Tuesday. The device, used with certain chemotherapies and immunotherapies, helps in creating electric fields that disrupt cancer cell growth. Data from the study shows that the device, along with a class of immunotherapies know as immune checkpoint inhibitors (ICI), extended survival by about eight months, compared to patients treated with ICI alone. Lung cancer is the most common cause of cancer-related death worldwide, and NSCLC accounts for about 85% of all lung cancers, the company said. Reporting by Khushi Mandowara in Bengaluru; Editing by Nivedita Bhattacharjee, Shinjini Ganguli and Maju SamuelOur Standards: The Thomson Reuters Trust Principles.

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Persons: Emily Bodnar, Jefferies, Michael Yee, Novocure, Khushi, Nivedita Bhattacharjee, Shinjini, Maju Samuel Organizations: ICI, Wainwright, U.S . Food, Drug Administration, Thomson Locations: United States, U.S, Bengaluru