A Study of GR1014 Cutaneous Gel for the Prevention of Skin Reactions Caused by Radiation Therapy for Breast Cancer

Inclusion Criteria: * Female patients with age ≥18 years. Those of childbearing potential must be using highly effective contraception methods during the study and for 30 days after the last administration of the study treatment and have a negative pregnancy test at screening and no more than 10 days prior to the administration of the first dose of study treatment * Patients with primary, localized breast cancer without metastases pTis, T1-3, pN0-N1mi, M0, who have undergone breast-conserving surgical excision and require adjuvant RT. The patients should be randomized after having recovered from the last surgery and, if delivered, the adjuvant chemotherapy. The patients can be included no matter the status of estrogen and progesterone receptors, malignancy grade, or HER2 status. * ECOG performance status 0-2 * Patients to be treated with ultra hypofractionated RT, 26 Gy in 5 fractions (5.2 Gy) on whole breast (EQD2 \> 42.6 Gy for α/β of 3) * Patients with no signs of dermatitis in the breast area to be irradiated, i.e., assessed Grade 0 as per CTCAE radiation dermatitis grading * Patients whom the investigator has deemed able to comply with the RT and investigational treatment done under the supervision of the medical personnel throughout the study period * Patients who have completed the appropriate washout period for any prior interventions or treatments Exclusion Criteria: * Pregnant and breastfeeding women * Patients under any treatment concomitant to radiotherapy test…