Lee was diagnosed with prostate cancer in January and underwent surgery on Monday at Singapore General Hospital.
Professor Christopher Cheng, who performed the surgery on Lee, said: "Prime Minister's pathology report is good. The disease is small but potentially significant. We are very glad we are able to detect and remove it in time. He should make a full recovery."
In a statement from the Prime Minister's Office, Lee thanked the "competent, dedicated and compassionate team" of radiologists, pathologists, doctors, nurses, physiotherapists and others who treated him.