The purpose of this observational study is:

To observe the efficacy, safety, and tolerability of Abstral ODT for the alleviation of breakthrough cancer pain in Korean patients with various cancers in real-world clinical settings and supplement and expand the previous cross-sectional survey results.

This is a multicenter, non-interventional, single-arm, non-randomized observational study designed to collect the efficacy, safety, and tolerability data of Abstral ODT for the treatment of breakthrough cancer pain in cancer patients in real-world outpatient and inpatient clinical settings.

As the purpose of this study is to investigate the efficacy and safety of Abstral ODT in routine clinical practice, drug prescription and treatment will be determined according to the medical judgment of the investigator, regardless of enrollment to this study. During the patient's visit to the institution, Abstral ODT will be prescribed according to the judgment of the investigator, and study participation will be suggested for this patient. Whether to participate in this study or not will not affect the patient's treatment (physician's prescription or diagnostic and therapeutic decision).

Due to the non-interventional observational nature of this study, there will be no visits or procedures to be performed mandatorily according to the protocol, and data will be collected at Week 1 (±3 days), Week 4 (±1 week), and Week 12 (±4 weeks) from the baseline visit according to the circumstances of clinical practice.

Status of successful dose titration for Abstral ODT will be determined according to the criteria in which dose titration is deemed successful when all of the following are met, and ineffective when one of the following is not met: no additional dose is administered within 2 h of administration of Abstral ODT during maintenance phase; Numeric Rating Scale scores at 30 and 60 min after administration is reduced by ≥2; adverse drug reactions are tolerable for the subject.The overall procedures of this study are as follows.

Inclusion Criteria:

1. Korean male and female adults at the age of 19 or older

2. In patient with Breakthrough cancer pain in inpatient or outpatient settings,

   • Patient with minimally 1 attack per day for the last week
   • Uncontrolled Breakthrough cancer pain patient with previous treatment with other fentanyl based on Invenstigator's judgment or patient who had not satisfied with previous treatment with other fentanyl at patient's request

3. Patient with opioid tolerance (treatment with at least 60 ㎎/day oral morphine, at least 25 mcg/hour transdermal fentanyl, at least 30 ㎎/day oxycodone, at least 8 ㎎/day oral hydromorphone, or other opioids at equivalent analgesic doses for 1 week or longer)

4. Patient who has been on opioids for the treatment of background cancer pain

5. Patient who did not administer Abstral ODT within 1 month prior to the baseline visit

6. Patient who signs the data release consent to data use.

Exclusion Criteria:

1. Patient for whom Abstral ODT is contraindicated based on its summary of product characteristics
2. Patient who is considered by the investigator to be ineligible for study participation for other reasons
3. Patient who is participating or participated in an opioid related clinical trial within 30 days prior to the baseline visit
4. Patient with neuropathic pain attacks

Male and female patient aged 19 and over

Patients who have been regularly on treatment with opioids for cancer pain from before study initiation and have no prior treatment with Abstral ODT within 30 days prior to study initiation.