The present invention provides for a method of treating a disease such as cancer, comprising the step of administering to a patient a therapeutically effective amount of an isomer or analog of monoterpene or sesquiterpene (or its derivative), such as an isoperillyl alcohol. The present invention also provides for a method of treating a disease comprising the step of administering to a patient a therapeutically effective amount of a derivative of an isomer or analog of monoterpene or sesquiterpene, such as an isoperillyl alcohol carbamate. The derivative may be an isoperillyl alcohol conjugated with a therapeutic agent such as a chemotherapeutic agent. The route of administration may vary, including inhalation, intranasal, oral, transdermal, intravenous, subcutaneous or intramuscular injection.