An Observational, Non-Interventional Trial to Assess Patient Satisfaction and Safety of Subsys™ Spray.

Inclusion Criteria: * Patients ≥ 18 years of age. * Subjects who are experiencing 1-4 episodes of break through pain per day in spite of optimized background analgesia and who have taken at least 60 mg/day of morphine (or equivalent analgesic) for at least 7 days. * Who are currently using Actiq® for their breakthrough pain and are being discontinued due to lack of efficacy, side effects, patient dissatisfaction or prescriber dissatisfaction with treatment. * Are able to follow and complete all necessary study procedures. * Are willing and able to give written informed consent before participating in the study. * Enrolled in the class wide REMS as verified by the study personnel. Exclusion Criteria: * Subjects who are not opioid tolerant. * Using a rapid onset opioid other than Actiq® to manage their breakthrough pain. * Have physical abnormalities of the floor of the mouth that could affect absorption as determined by investigator. * Are subjects with uncontrolled or rapidly escalating pain. * Are subjects with a history of alcohol or substance abuse within the last 3 years. * Have a clinically significant medical history (past or present) of any disease that would compromise the study or the well-being of the subject. * Are subjects who have participated in another clinical trial with an analgesic within the last month. * Are female subjects with a positive pregnancy test or who are currently lactating. * Are subjects who are taking medications that are known inhibitors of the CYP3A4 isozyme, such as ketoconazole. * Are subjects who have taken a monoamine inhibitor within 14 days before a dose of study medication. * Opioid being used for chronic migraine or acute pain. * Are subjects who are unsuitable for inclusion for any other reason, in the opinion of the investigator.