Objectives Photobiomodulation (PBM) has been described as an adjunct method for skin recovery, though clinical studies in radiodermatitis are scarce. Our aim was to evaluate the impact of PBM in reducing the incidence of radiodermatitis in breast cancer.

Methods A single center randomized double-blind controlled trial (NCT04059809) was carried out and included women who underwent conservative surgery or mastectomy, without immediate breast reconstruction and treated with 3D radiotherapy. Patients were randomly assigned (1:1) to receive usual skin care ± red PBM (660nm) with energy of 3 Joules every 2cm along the breast or plastron. Radiodermatitis were blindly classified by 2 professionals and blinded for the patient.

Results A total of 110 cases were predefined as the study sample size. The recruitment stopped after the interim analysis at 48 cases (26 women in PBM group and 22 in control). Median age was 51.5 years (range,29–78), median total radiation dose of 50.4Gy (range,42–55)%) and 36(75%) cases had conservative surgery. The clinical and pathological variables did not differ between groups. Total of 16 (33.3%) cases had radiodermatitis in the breast plastron and 42 (87.5%) outside the breast plastron area. Radiodermatitis in the breast/plastron was significantly lower in PBM group compared to control [11.5% vs. 59.1%; HR 0.090 (95%CI:0.021–0.39); p=0.001]. However, there was no difference in radiodermatitis rates outside the breast/plastron site (not involved with PBM) for the PBM group compared to the control group [HR1.21 (95%CI:0.21–6.7); p=0.82].

Conclusions Our results suggest that PBM in women with breast cancer treated by adjuvant radiation significantly reduces the risk of radiodermatitis