Gabapentin, Methadone, and Oxycodone With or Without Venlafaxine Hydrochloride in Managing Pain in Participants With Stage II-IV Squamous Cell Head and Neck Cancer Undergoing Chemoradiation Therapy

Gabapentin, Methadone, and Oxycodone With or Without Venlafaxine Hydrochloride in Managing Pain in Participants With Stage II-IV Squamous Cell Head and Neck Cancer Undergoing Chemoradiation Therapy