The purpose of this study is to evaluate the long-term safety and efficacy of OraVescent fentanyl to treat breakthrough pain episodes in cancer patients who are already opioid tolerant.

The objective of this study is to determine the tolerability and safety of OraVescent fentanyl when used long term to relieve breakthrough pain in opioid tolerant cancer patients.

Inclusion Criteria:

• 18-80 years of age
• Average of 1-4 breakthrough pain episodes per day
• Opioid tolerant
• Histologically documented diagnosis of a malignant solid tumor or hematological malignancy

Exclusion Criteria:

• Primary breakthrough pain is not related to cancer in any way
• Opioid or fentanyl intolerance
• Chronic obstructive pulmonary disease (COPD) or heart disease
• Sleep apnea or active brain metastases with increased cranial pressure