Background: Radiation-induced dermatitis is commonly seen during radiotherapy for breast cancer. Melatonin-based creams have shown a protective effect against ultraviolet-induced erythema and a radioprotective effect in rats.

Objectives: To evaluate the efficacy of melatonin-containing cream in minimizing acute radiation dermatitis. 

Methods: In this phase II, prospective, randomized, placebo-controlled double-blind study, patients who underwent breast-conserving surgery for stage 0-2 breast cancer were randomly allocated to melatonin emulsion (26 women) or placebo (21 women) for twice daily use during radiation treatment and 2 weeks following the end of radiotherapy. All women received 50 Gy whole breast radiation therapy with 2 Gy/fx using computed tomography-based 3D planning. Patients were examined and completed a detailed questionnaire weekly and 2 weeks following the end of treatment.

Results: The occurrence of grade 1/2 acute radiation dermatitis was significantly lower (59% vs. 90%, P = 0.038) in the melatonin group. Women older than 50 had significantly less dermatitis than younger patients (56% vs. 100%, P = 0.021). The maximal radiation dermatitis in the study group was grade 2 in 15% of the treated patients.

Conclusions: Patients treated with melatonin-containing emulsion experienced significantly reduced radiation dermatitis compared to patients receiving placebo.