Topical/Oral Melatonin for Preventing Concurrent Radiochemotherapy Induced Oral Mucositis/Xerostomia Cancer Patients

Drug: Melatonin 20 mg/ 10 ml melatonin suspension gargle for 2 minutes before radiation 15 minutes and 20 mg melatonin gelatin capsule taken orally after 21:00 hours each night throughout the study

Drug: Melatonin 20 mg/ 10 ml placebo suspension gargle for 2 minutes before radiation 15 minutes and 20 mg placebo gelatin capsule taken orally after 21:00 hours each night throughout the study