Cancer treatment is multidisciplinary and may include radiotherapy. Treatment-related complications represent a burden for patients and the healthcare system. Early recognition of radiotherapy-related side effects is important for timely clinical interventions and improved quality of care. This study aims to improve comprehensive patient management during and after radiotherapy through development and implementation of a web-based application using standardized electronic patient-reported outcome questionnaires (PROMs). Patients will report radiotherapy-related symptoms and quality of life through web-based questionnaires that will be securely transmitted to the Institute of Oncology Ljubljana for review by healthcare professionals. Responses will be categorized using a traffic-light system to guide clinical actions and optimize follow-up visits.

Radiotherapy is an essential modality in cancer treatment, but it may cause acute and chronic adverse effects. Effective detection of complications during radiotherapy is crucial for timely clinical response, prevention of long-term consequences, and improvement of patient quality of life. Patient-reported outcome measures (PROMs) are widely used internationally and increasingly implemented in electronic form.

This prospective clinical study aims to develop and implement a web-based application that enables cancer patients to report radiotherapy-related complications and quality of life outcomes through standardized electronic questionnaires. The application will support remote monitoring and allow healthcare professionals to optimize clinical workload and reduce unnecessary outpatient visits.

Patients treated with radiotherapy at the Institute of Oncology Ljubljana will be invited to participate. Before inclusion, patients will sign written informed consent and will receive instructions regarding application use. During radiotherapy, patients will complete electronic questionnaires weekly until completion of treatment. After radiotherapy, patients will complete questionnaires before each scheduled follow-up visit during the first two years.

Questionnaires will be transmitted securely via HTTPS to a database at the Institute of Oncology Ljubljana. Patient responses will be categorized into three severity groups using a traffic-light system: green (grade 1), yellow (grade 2), and red (grade 3). Patients in the red category will be contacted and scheduled for an early clinical visit, patients in the yellow category will be monitored more frequently, and patients in the green category will be reviewed at the end of radiotherapy and at regular follow-up appointments.

The study will evaluate the appropriateness of questionnaires and responses for prediction of radiotherapy-related adverse effects. Patient-reported symptom severity will be compared with physician-reported toxicity grading. Quality of life outcomes and healthcare service utilization will also be assessed. The application will be evaluated using performance indicators such as accuracy, sensitivity, and specificity. Statistical analysis will include descriptive statistics, frequency distributions, and linear mixed-effects models for quality of life evaluation.

Inclusion Criteria:

• Patients receiving radiotherapy for gynecologic cancer, urologic cancer, or breast cancer at the Institute of Oncology Ljubljana.
• Ability to access and use the web-based application on a smartphone, computer, or tablet.
• Signed written informed consent.

Exclusion Criteria:

• Inability to understand the questionnaire questions and provide meaningful answers.