The present invention concerns a method for preventing and/or treating cancer in a patient comprising administering an effective amount of substantially purified D enantiomer of difluoromethylornithine (D-DFMO) or an analog of D-DFMO to the patient. D-DFMO or an analog thereof is administered at a dose of about 0.05 to about 20.0 gm/M<2>/day. D-DFMO or an analog thereof may be administered more than once for the treatment and/or prevention of cancer. Methods of administration as well as compositions and formulations of substantially purified D-DFMO and analogs of D-DFMO are described.
