A method for treating cancer is described using combination therapies comprising the use of hyperbaric oxygen with histone deacetylase inhibitors, with and without glycolytic therapies. The patient is subjected to a hyperbaric environment of substantially pure oxygen. A predetermined dose of one or more HDACI substances is administered to the patient. In addition, glycolitic inhibitors may also be administered. Dosages, pressures, and durations are selected as described herein to have a therapeutic effect on the patient.