Catherine, Princess of Wales, was not at Royal Ascot on Wednesday, with a royal source citing her need for balance as she returns to public engagements after being treated for cancer last year.

The princess canceled plans to attend the horse racing event on Wednesday as she tries to find the “right balance” in her recovery from cancer, Kensington Palace said.

Britain’s Catherine, Princess of Wales, who is recovering from cancer, has withdrawn from the Royal Ascot race meeting, her Kensington Palace office said on Wednesday.