Background

Radiation-induced dermatitis (RID) is one of the most common and distressing adverse effects experienced by patients undergoing PORT, with an incidence exceeding 90%. RID can range in severity, with grade 2 and higher being particularly troublesome.[1,2] These higher-grade reactions are characterized by erythema, pruritus, burning sensations, and in severe cases, pain and ulceration.[1,2] Such symptoms not only reduce patients’ quality of life but may also compromise treatment compliance and lead to interruptions in the radiotherapy regimen, potentially affecting oncologic outcomes.

Despite the high prevalence and clinical significance of RID, prophylactic and therapeutic options remain limited. The current standard of care typically includes general skin care advice and the use of topical corticosteroids. However, the evidence supporting these interventions is inconclusive, with prior studies showing mixed results for agents such as mometasone and betamethasone.[3,4]

Diclofenac, a cyclooxygenase-2 (COX-2) inhibitor, is a widely used non-steroidal anti-inflammatory drug (NSAID) known for its anti-inflammatory and analgesic effects when administered orally. [5] However, concerns regarding systemic side effects limit its long-term oral use. Topical formulations of diclofenac offer an alternative with a favourable safety profile. Topical diclofenac gel has demonstrated efficacy in reducing cutaneous inflammatory responses and may modulate cytokine-mediated pathways implicated in RID pathogenesis.[5] Notably, a randomized controlled trial by Santosh et al. showed that topical diclofenac gel was effective in managing capecitabine-induced hand-foot syndrome (HFS), providing a rationale for investigating its potential benefit in RID.[6]

At our institution, we do not follow any uniform guideline for preventing RID. In cases of severe RID, temporary cessation of radiotherapy becomes necessary. However, there is currently no established protocol for the prophylactic use of topical diclofenac throughout the entire duration of radiation therapy.

Given the known anti-inflammatory effects of topical diclofenac and its favourable safety profile, we hypothesize that its regular application may mitigate the severity of RID, reduce treatment interruptions, and improve patient comfort during PORT. To our knowledge, the prophylactic use of once-daily topical diclofenac gel for the full course of PORT has not been systematically evaluated.

This study aims to investigate the efficacy and safety of topical diclofenac gel in preventing and reducing the severity of radiation-induced dermatitis in patients receiving post-operative radiotherapy.