LONDON -- King Charles III returned to public duties on Tuesday, visiting a cancer treatment charity and beginning his carefully managed comeback after the monarch's own cancer diagnosis sidelined him for three months.

The event marks the king's first formal public engagement since Feb. 6, when Buckingham Palace announced that he would be taking a break from public duties to focus on his treatment for an undisclosed type of cancer.

It will be the first of several public appearances Charles will make in the coming weeks as he prepares to host a state visit by the emperor and empress of Japan in June.

It is unclear how many of the summer's traditional royal events, including the king's formal birthday parade and the horse racing at Royal Ascot, Charles will attend as his treatment continues. The palace said last week that doctors were "very encouraged" by the king's progress, but his schedule would be adjusted as needed to protect his recovery.

For now, Tuesday's appearance gives Charles another opportunity to raise awareness of the benefits of early diagnosis and treatment of cancer and other health problems as he has done throughout his illness.

Unlike most royals before him, Charles chose to publicly disclose details about his health when he first underwent treatment for an enlarged prostate and later when he was diagnosed with cancer. The decision raised awareness of these issues.

The National Health Service in England said the number of people seeking advice about prostate problems increased 11-fold in the weeks after Charles' announced he was undergoing treatment.