Objective: The assessment of Avena Sativa cream efficacy on skin reactions caused by radiotherapy in patients with breast cancer. Interventions: After obtaining informed consent from the patient, at the first time of beginning radiotherapy we will recommend to patients use the cream which prepared from oat extract, three times a day each 8 hours daily (TDS), in the radiotherapy area, amount of one finger (FTU) will be applied uniformly with the index finger (considerably in different patients based on the extent of the lesion, this unit can be doubled) and for 3 hours, they must avoid washing the area. In the control group patients will use placebo (extract-free cream base). Then, The skin reactions such as tenderness, pain, itching, burning sensation, erythema, dry desquamation and the grade of dermatitis caused by radiotherapy will be examined at the intervals of 10 days after initiation of treatment (start of the major erythema reaction), 28 days after initiation of treatment (start of dry desquamation), on the last day of radiotherapy and after that in two times with one week interval, after the end of radiotherapy participants will be followed up. Then the data will be collected with RTOG questionnaire (to determine the grade of radio dermatitis) and researcher-made questionnaire which its validity and reliability will be determined.