U.S. Severe Oral Mucositis Market, By Drug Type (Palifermin, Amifostine, Chlorhexidine, Sucralfate, Late Phase (Avasopasem and Dusquetide)), By Cause (Chemotherapy and Radiotherapy), By Grade (Grade III and Grade IV), By Distribution Channel (Hospital Pharmacies, Retail Pharmacies, and Online Pharmacies) - Size, Share, Outlook, and Opportunity Analysis, 2021 - 2028