Primary:

• To compare the efficacy of nasal fentanyl (NF) to oral transmucosal fentanyl (Actiq®) (hereafter Actiq) in the management of breakthrough pain in cancer patients.

Secondary:

• To compare patients' general impression and preference of NF and Actiq
• To explore the relationship between NF doses and dose of current opioid for breakthrough pain (BTP) and the relationship between dose of NF and of background opioid
• To assess safety and tolerability of NF

Inclusion Criteria:

• Adult in- or out patient with cancer and breakthrough pain; using a stable, chronic opioid treatment for background pain.
• Minimum three BTP episodes per week and maximum four per day. Life expectancy of at least three months.
• Chemotherapy and palliative radiotherapy (except facial radiotherapy) are allowed.
• Randomisation in previous studies with NF, i.e. FT-016-IM, FT-017-IM or FT-018-IM, is not allowed.
• Previous use of Actiq is accepted.