SINGAPORE - Singapore Prime Minister Lee Hsien Loong underwent successful surgery for prostate cancer on Monday and is expected to recover fully, his office said. It is the second bout with cancer for 63-year-old Lee, who had also undergone chemotherapy for lymphoma in 1993 and is now in remission. “Prime Minister Lee Hsien Loong’s surgery was successful,” his office said in a statement. The statement quoted Christopher Cheng, the lead urologist at the Singapore General Hospital who carried out the operation, as saying: “The surgery went very smoothly, and he is expected to recover fully.” Cheng confirmed that Lee’s prostate cancer is not linked to his previous lymphoma, the statement added.