 Dulles developed colon cancer, for which he was first operated on in November 1956 when it had caused a bowel perforation.He experienced abdominal pain at the end of 1958 and was hospitalized with a diagnosis of diverticulitis.In January 1959, Dulles returned to work, but with more pain and declining health underwent abdominal surgery in February at Walter Reed Army Medical Center when the cancer's recurrence became evident.