Among other associations he is member and International Fellow of the American Gastroenterological Association, American Colleague of Gastroenterology, and the Asociación Española de Gastroenterología (AEG). He was president of the AEG for 4 years and was also member of the General Assembly of the United European Gastroenterology Federation.

Dr. Lanas is actively involved in both clinical and basic investigation relating to acid peptic disorders, particularly NSAIDs, aspirin and gastrointestinal toxicity, as well as mechanisms of chemoprevention of colon cancer and Barrett's esophagus. Professor Lanas has published more than 350 articles in the most prestigious Medical Journals including the New England Journal of Medicine, The Lancet, Gastroenterology, Gut, The American Journal of Gastroenterology, Nature, American Journal of Medicine among others. He has also been invited as Visiting Professor to different American and European Universities and to numerous International Congresses and Symposiums