Efficacy of Photobiomodulation in Mitigating Radiation-Induced Neck Fibrosis in Patients With Head and Neck Cancer: A Phase-IIa Randomized Controlled Trial Study Protocol

Background: Radiation-induced neck fibrosis (RIF-N) significantly impairs function, cosmesis, and quality of life in head and neck cancer (HNC) survivors. Current management options are limited and largely experimental. Photobiomodulation therapy (PBMT), a safe, noninvasive intervention, shows antifibrotic potential in early studies. This randomized controlled trial evaluates its tolerance and efficacy in mitigating RIF-N in patients with HNC. Methods: In this phase-IIa, participant-blinded, two-arm parallel-group randomized controlled trial, a minimum of 60 patients will be randomized (1:1) to PBMT + standard care or sham-PBMT + standard care by online software. The PBMT dose, adapted from WALT guidelines, will be delivered using low-level LASER during radiation therapy (RT). Standard care includes supervised exercises during the course of RT, followed by a booklet-guided home exercise program. Feasibility will be qualitatively described based on recruitment, protocol adherence, and retention. Tolerance to PBMT will be determined by evaluating for an increase in erythema, irritation, burning sensation, or pain at the PBMT application site. Efficacy will be determined using (i) fibrosis severity (shear-wave elastography of sternocleidomastoid and Late Effects of Normal Tissues-Subjective, Objective, Management, Analytic Scale); (ii) neck range of motion (goniometry and tape measurements); (iii) quality of life (Functional Assessment of Cancer Therapy-Head & Neck) as primary outcomes. The secondary outcome (radiation dermatitis) will be assessed by CTCAE v5.0. Assessments will be conducted at baseline and 3-, 6-, 9-, and 12-month post-RT, and the efficacy of PBMT will be determined by evaluating group and time interaction. Discussion: If found well-tolerated and efficacious, PBMT may offer a feasible, noninvasive strategy to reduce RIF-N in HNC survivors, warranting confirmation in high-quality phase IIb trials.