CARACAS, Venezuela (AP) -- Venezuelan President Hugo Chavez announced plans to travel to Cuba as early as Tuesday for more medical treatment after spending much of the past 18 months fighting cancer. In a written request to the legislature, which was read on television by National Assembly President Diosdado Cabello, Chavez said that doctors have recommended he "begin special treatment consisting of various sessions of hyperbaric oxygenation" and physical therapy to continue "consolidating the process of strengthening health." The request did not provide more details about the treatment. It said Chavez would travel to Cuba as early as Tuesday, but did not state how long he will stay, though Chavez said he would be back by Jan. 10, when he is being sworn in for a fourth term. Venezuelan law requires presidents to receive legislative approval before leaving the country for extended periods. Hyperbaric treatments involve breathing pure oxygen in pressurized chambers and can be used for a broad variety of conditions. The American Cancer Society says on its website that the treatment is sometimes used to treat wounds, injuries and infections, as well as delayed bone damage caused by radiation therapy. It says there is no evidence it can cure cancer. The 58-year-old president first underwent cancer treatment in Cuba in June 2011 and suffered a relapse in February. He has since said he's recovered from the pelvic cancer and won re-election in October. Throughout his previous chemotherapy and radiation treatments, Chavez kept many details of his illness secret, including the type of cancer and the precise location of the tumors.