Dr. Tan began his career as an Assistant Professor in the Department of Surgery at Tohoku University, and held this post from 1973 until 1985; he then went on to serve as Head of the Department of Surgery at Ofunato Prefectural Hospital from 1985 through 1988, at Kitakami Prefectural Hospital from 1988 through 1994, and at Isawa Prefectural Hospital in Mizusawa, Japan from 1994 through 1998. From 1998 until 2011 he served as Vice Director of Wakayanagi Hospital in Kurihara, Japan, and from 2011 to 2013 he held the position of Director of Kitakamikiboen Geriatric Health and Welfare Facilities in Kitakami, Japan. In 2013 D r. Tan began in his current position as Director of NAKADA Geriatric Health and Welfare Facilities in Tome, Japan.

Dr. Tan is a Member of the New York Academy of Sciences, the American Chemical Society, the American Association for the Advancement of Science, and the International Society of Personalized Medicine. Additionally, he serves on the Editorial Board of Personalized Medicine Universe. Dr. Tan received the World Lifetime Achievement Award from ABI in 1999, and the Gold Star Award from IBC in 2000.

Moreover, Dr. Tan has been featured in 'Who's Who in America' (Marquis Who's Who), in consecutive editions from 2009 through 2014 (63rd through 68th editions), 'Who's Who in the World' (Marquis Who's Who) in consecutive editions from 2009 through 2014 (15th through 31st editions), 'Who's Who in Asia' (Marquis Who's Who) in 2007 and 2012 (1st and 2nd editions), 'Who's Who in Medicine and Healthcare' (Marquis Who's Who), in consecutive editions from 2000 through 2012 (3rd through 8th editions), 'Who's Who in Science and Engineering' (Marquis Who's Who) in consecutive editions from 1996 through 2012 (3rd through 11th editions), 'The Royal Book of Diplomacy and Science' (London Diplomatic Academy) in 2005 and 2009 (5th and 9th editions), 'World Who's Who HALL of FAME' in 1999, 'Outstanding People of the 20th Century, in 1999, 'Dictionary of International Biography' Twenty Seventh Edition 1999, 'Dictionary of International Biography' Twenty-Eighth Edition 2000, 'Dictionary of International Biography' Twenty Ninth Edition 2001, 'The First Five Hundred at the new millennium' in 2000, 'Who's Who in the 21st Century' First Edition 2002, ë2000 Outstanding Scientists of the 20th Century' Second Edition 2001, ‘2000 Outstanding Scientists of the 21st Century’, 2004, 'Five hundred Leaders of Influence' 8th edition 1999 (ABI), 'ASIA/PACIFIC-WHO's WHO' Volume Fifth 2004 Rifacimento International, New Delhi, India, Bibliotheque: World Wide 'The Global 500 Leaders for the new millennium' 2001, 'The Millennium Edition 500 Great Asians of the Early 21st Century' 2002, and ‘500 Distinguished Professors & Scholars of the BWW Society/IAPGS' 2004.

In his free time Dr. Tan enjoys reading, watching movies, listening to music, traveling, and photography.