UPDATE 1-Merck's Keytruda extends lung cancer survival in 2 trials

CHICAGO, June 3 (Reuters) - Merck & Co's immunotherapy Keytruda improved survival as a stand-alone treatment for newly-diagnosed lung cancer patients and with chemotherapy for hard-to-treat squamous cell lung cancer, new data released on Sunday showed, further cementing the company's lead in the most lucrative oncology market.