Dermatitis During Adjuvant Irradiation for BREAst Cancer: Grade ≥2 Radiation Dermatitis in Breast Cancer Patients with or Without a Mobile Application (Reminder-App)

The main goal of this trial is to evaluate whether standard skin care supported by a reminder app is superior to standard skin care alone with respect to prevention of grade ≥2 radiation dermatitis in patients receiving adjuvant radiotherapy for invasive breast cancer. Radiation dermatitis will be assessed by an observer (specially trained nurse, technician, or physician) different from the person who performs the routine visit of the patient ("blinded observer concept"), at the start of radiotherapy and weekly during the course of radiotherapy, and at the end of the radiotherapy course (=EOT) according to CTCAE v5.0. Secondary aims include pain (radiation fields), patient satisfaction with the reminder app (Arm A), impact of the reminder app on the use of health technology (Arm A), and benefit from support by staff members and/or the UKSH academy regarding the use of the reminder app (Arm A).

This is a multinational, randomized, active-controlled, open-label, multicenter, parallel-group trial, which compares the following treatments of radiation related skin toxicity in patients with breast cancer: Standard skin care supported by a reminder app (Arm A) vs. standard skin care alone (Arm B). Stratification will be done using the following prognostic factors:

1. Treatment volume: Breast or chest wall alone vs. breast or chest wall plus lymph nodes
2. Radiation boost: Yes vs. no
3. At least one risk factor of dermatitis: Yes vs. no Risk factors include chronic inflammatory disease, significant cardiovascular disease, and smoking history of >10 pack years.

After registration, patients will be randomized in a 1:1 ratio to Arm A or Arm B for treatment of radiation related skin toxicity. A stratified block-randomization with random block size will be performed via electronic CRF. The results of the randomization will be visible only after the input of the stratification factors and only for the corresponding patient.

This document will be kept at the institution which performs the randomization until the end of the study. Afterwards, the original randomization list will be kept in the trial master file at the trial center of the coordinating investigator for a minimum of 10 years after the final report. The randomization will be performed via electronic CRF centrally by an external company using its standard software. The proceeding for randomization is based on standard operating procedures (SOPs) of this company. Once the randomization is allocated to the patient it cannot be changed.