As one of Canada's premier oncologists, his work as a clinician, surgeon and research scientist has been the catalyst for innovations in the treatment of breast cancer. He has been an effective advocate for the replacement of radical surgery, widely employed in the past, with a combination of less invasive procedures, supplemented with chemotherapy and radiation. He has served as President of the National Cancer Institute of Canada and National Director of the Canadian Cancer Society, where he improved the standards of care for patients across the country.