[2] Lewis was a Professor of Surgery and Medicine Memorial Sloan-Kettering Cancer Center,[3] before working in the biotechnology and healthcare industries, serving in several CEO and Chairman roles.
At Sloan-Kettering, he completed postdoctoral research in the immunology lab of Alan Houghton.
This includes the early use of peptides and DNA vaccines with active immunotherapy using T cells,[8][9] a better understanding of the biology and role of surgery in retroperitoneal sarcoma,[10] the liberal and correct use of re-resection in extremity sarcoma,[11] and the potential use of vaccines in pancreatic cancer.
[12] Lewis has authored over 200 scientific publications, which include work in the biology and treatment of sarcoma, the biology and treatment of pancreatic cancer, molecular cancer vaccines, gene therapy and the translation of laboratory findings to the clinic, in addition to writing chapters or sections in 15 textbooks.
[14] During his career as a physician, Lewis cared for Kitch Christie, the head coach of the 1995 South Africa national rugby union team,[15] Chief Justice Ismail Mahomed, and Kate McGarrigle.