The purpose of this study is to show the clinical usefulness of fentanyl matrix by measuring satisfaction with pain treatment after administering fentanyl matrix in patients whose pain was not controlled sufficiently with the previous analgesic use in real practice at the investigator's discretion.

This is a multi-center, open-label (all people know the identity of the intervention), prospective (the patients are identified and then followed forward in time for the outcome of the study) observational study. The study population comprises patients who are admitted to a study center during the study period and are receiving a strong oral long-acting opioid analgesic but deemed to control pain insufficiently. Since this study is an observational study conducted in real practice, a dose of fentanyl matrix should be adjusted depending on an individual patient's response at the investigator's discretion. However, for the patients whose pain is not sufficiently controlled despite administration of strong long-acting opioid analgesics, the minimum initial dose will be fentanyl matrix 75 micrograms/h and the investigator can adjust dosage according to the degree of the patients' pain control during the 9 days of the study period.

Inclusion Criteria:

• Patients complaining of cancer pain which requires administration of long-acting opioid analgesics
• Patients whose pain is not sufficiently controlled despite administration of strong long-acting opioid analgesics
• Patients who are deemed to need an initial minimum dose of fentanyl matrix 75 micrograms/h
• Patients who signed the informed consent form

Exclusion Criteria:

• Patients with a history of or current drug or alcohol abuse
• Childbearing women who are pregnant or likely to be pregnant during the study period and men who are neither infertile nor willing to refrain from sexual relations but whose partner does not conduct an effective contraception
• Patients who are unable to use a transdermal system due to skin disease
• Patients with history of hypersensitivity to opioid analgesics
• Patients who are not eligible for the study participation based on warnings, precautions and contraindications in the package insert of the study drug at the investigator's discretion

Patients who are admitted to a study center during the study period and are receiving a strong oral long-acting opioid analgesic but deemed to control pain insufficiently.