The goal of this clinical trial is to learn if Gelclair lubricant gel can help manage Oral Mucositis (OM) among Oropharyngeal and Oral cavity cancer patients receiving radiation treatment. The main questions it aims to answer are:

1. Does Gelclair help to manage the symptoms of OM and decrease its severity?
2. What do participants report as the maximum levels of pain and difficulties with swallowing?

Researchers will compare Gelclair to the standard of care mouthwash treatment for OM (currently used for all patients with symptomatic OM) to see if Gelclair is helpful in managing oral mucositis.

For the cohort using Gelclair, participants will:

1. Take the prescribed treatment for OM (Gelclair or Oncology mouthwash) once it is diagnosed, up to and including 4 weeks after radiation completes.
2. Complete a weekly survey about their OM symptoms up to and including 4 weeks after radiation completes.

2. Report any problems experienced with prescribed treatment for OM (Gelclair or mouthwash).

The same data will be collected for the cohort using standard of care mouthwash for comparison.

Radiotherapy (RT) induced mucositis, including oral mucositis (OM), is the most common high-grade toxicity observed during high dose RT for Head and Neck Cancer (HNC). Prevention usually consists of adhering to oral care protocols, avoiding irritants, and avoiding mucosal hot spots in the RT plan. Once it occurs, analgesic treatments include various mixtures of pain relief mouthwashes, NSAIDS, opioids, and steroids and antifungals as indicated.

Mucoadhesive topical coating agents have been used to treat RT induced OM.

Study eligible patients will be offered participation after clinic consultation has taken place. They will be detailed provided study information and if they consent in writing, will be assigned to the standard of care cohort (16 patients) and the experimental cohort (32 patients) in a sequential format.

The first cohort of 16 patients will be evaluated for oral mucositis (OM) using CTCAE V5 criteria and Patient Reported Outcome questionnaires while undergoing management with current standard of care for symptomatic OM which includes lidocaine-based mouthwashes as initial treatment. The subsequent (experimental) cohort of 32 patients will begin treatment with Gelclair once symptomatic OM develops with the same evaluation parameters as the previous (control) cohort. Gelclair is a hyaluronic acid hydrogel that acts as a protective film in the management of OM. This product is used internationally and has been recently approved by Health Canada as a Class 2 Medical Device with an indication to manage the symptoms of OM caused by radiotherapy and chemotherapy.

After collection of baseline data (including age, sex, cancer diagnosis and staging, relevant past medical history, treatment plan, weight, nutrional status), weekly data (includes OM grading, Patient Reported Outcome for OM, weight, analgesic requirements, parenteral nutrional requirements, side effects, adherence to protocol) during radiation therapy (RT) and for 4 weeks after RT completion is recorded.

Upon study completion, analysis will be aimed at the following outcomes:

Primary Objective: Explore the effectiveness of GelClair versus SOC mouth wash in the management of symptomatic radiation-induced OM.

Secondary Objectives: Patient reported outcomes (PRO) for maximum levels reached of odynophagia and dysphagia (assessed weekly from RT start until 4 weeks after completion)

Other measurement outcomes include time to initiation of opioid (or increase in baseline dose) measured in days, weight loss, treatment delays / modifications due to OM, requirement for feeding tube, adherence to treatment protocol, cost analysis for SOC mouthwash versus GelClair based on total days use of each agent.

Inclusion Criteria:

• Diagnosed with primary mucosal squamous cell carcinoma of the oropharynx or oral cavity
• Treatment plan includes at least 60Gy of daily radiotherapy, with or without concurrent chemotherapy
• Highly likely to develop OM CTCAE v5.0, grade 2
• Can read and understand English

Exclusion Criteria:

- Patients who already have parenteral feeding tubes prescribed

This is a single center study and IPD will not be shared with anyone outside the study personnel at this center.