In the context of radiotherapy, control of breakthrough pain represents a special challenge. Patients undergoing radiotherapy may experience different situations of pain that may be due to the need to remain immobilized during radiotherapy session, the need to wear an immobilization mask (head and neck cancer), the odynophagia caused by mucositis, defecation after the development of proctitis, or sudden pain during the night causing sleep disturbances.

In a survey conducted in radiation oncology services more than half of patients treated with radiotherapy experienced pain, and 39% of patients reported that their pain was not treated properly. This situation may increase the patient's anxiety, dissatisfaction with treatment, affect their quality of life and can even come to refuse radiotherapy treatment.

This post-authorization observational study will assess the quality of life of cancer patients with breakthrough cancer pain treated in radiotherapy services in Spanish hospitals.

Inclusion Criteria:

• Patients > 18 years
• Cancer Patients
• Patients attended in radiation oncology consultations with palliative intent
• Life expectancy > 6 months
• Written informed consent
• Patients with baseline controlled cancer pain with opioids who are diagnosed of breakthrough cancer pain by Davies algorithm

Exclusion Criteria:

• Untreated patients with opioids for baseline pain
• Patients who are not opioid tolerant
• Serious psychiatric disorder or any disease or condition that prevents the collection of data
• Patients with evidence of opioid addiction or history of drug or alcohol abuse

Patients with breakthrough cancer pain treated in Radiation Oncology services with palliative intent will be included