Treatment of Breakthrough Cancer Pain According to European Guidelines

Inclusion Criteria: * Male and female patients of any ethnic origin of ≥ 18 years. * Patients diagnosed with locally advanced or recurrent metastatic cancer (histologic or cytologic diagnosis), with BTcP, as assessed by the Investigator. * Opioid-tolerant patients receiving doses of oral morphine equivalent daily doses (OMEDD) of at least 60 mg. * Drugs for BTcP treatment, if any, must be used according to the relevant SmPC. * Eastern Cooperative Oncology Group (ECOG) performance status with a score of 0, or 1, or 2. * Patients with life expectancy \> 3 months. * Patients legally capable of giving their consent to participate in the study and available to sign and date the written informed consent. Exclusion Criteria: * Patients with previous or current history of a clinically significant neurological/psychiatric disorder and/or any substance abuse or dependence that, according to the Investigator's judgement, can impair the study end-points/results. * Patients who have been taking antidepressants and/or drugs acting on pain and who take them on a regular basis during the observation period, can be enrolled. * Any medical condition or situation complicating the collection of study data, as determined by the Investigator.