This is a multi-centre (up to 10 regional cancer centres in England, Scotland and Wales), 2 arm parallel group, blinded randomised controlled trial (RCT). LiTEFORM aims to evaluate the effectiveness and efficiency of LLLT in reducing the severity and impact of OM in adult patients receiving (C)RT for HNC.

Patients will be randomised 1:1 to receive standard care plus LLLT (n=190) verses standard care plus sham LLLT (n=190). Both arms will receive the current standard care which includes optimisation of good oral hygiene, hydration and use of analgesia, topical analgesics and coating gels for pain management. Treatment allocation will be stratified by two factors: 1. planned treatment (radiotherapy alone or chemo-radiotherapy 2. Unilateral or bilateral radiotherapy fields.

As part of the qualitative evaluation, a sample of patients who have consented or declined the main trial will be invited to take part in a telephone interview (n≤36). Staff at participating sites involved in trial recruitment/patient care, staff delivering LLLT, and other relevant members of the HNC team, will also be invited to take part in interviews. There will be observations of trial training and audio-recording of recruitment discussions (approximately 6-8 per site selected for analysis).