 RATIONALE: Drugs used in chemotherapy such as isotretinoin use different ways to stop tumor cells from dividing so they stop growing or die. Interferon alfa may interfere with the growth of tumor cells. Vitamin E may be able to decrease side effects caused by isotretinoin. It is not yet known whether combining isotretinoin and interferon alfa with vitamin E is more effective than observation in preventing recurrence of head and neck cancer after surgery andor radiation therapy. 