An Assessment of the Ability of Fentanyl Citrate Nasal Spray to Manage Breakthrough Pain in Cancer Patients.

Inclusion Criteria: * Patients who meet the following criteria will be eligible: 1. At least 18 years of age or older. 2. Diagnosed with cancer. 3. Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2. 4. Patients with cancer who are experiencing episodes of BTPc in spite of optimized background analgesia with at least 60 mg/day of morphine (or equivalent analgesic) for at least 7 days. 5. Patients with cancer currently using an SAO (short acting opioid) to manage their episodes of BTPc. 6. Patients with cancer who have failed to obtain a timely response, as determined by the Principal Investigator, to pain from their SAO therapy. 7. Laboratory values consistent with the stage of disease that are deemed clinically insignificant by the investigator. 8. Female patients of child bearing potential or male patients with partners of child bearing potential who are using an adequate form of contraception before study entry, and agree to use an adequate form of contraception for an additional month after the study. Adequate contraception is defined as the use of any hormonal contraception or intra-uterine device by the female patient/partner plus use by at least 1 of the partners of an additional spermicide-containing barrier method of contraception. The use of a barrier method alone or abstinence is not considered adequate. 9. Willing and able to give written informed consent before participating in the study. Exclusion Criteria: * Patients meeting the following criteria will be excluded from the study: 1. Patients who are not opioid tolerant. 2. Patients with a known intolerance or hypersensitivity to fentanyl. 3. Physical abnormalities of the nose that could affect nasal absorption. 4. Patients with uncontrolled or rapidly escalating pain. 5. Patients with a history of alcohol or substance abuse. 6. A clinically significant medical history (past or present) of any disease that would compromise the study or the well-being of the patient . 7. Patients who have participated in another clinical trial with an analgesic within the last month. 8. Patients who have previously used FCNS and did not have adequate responses. 9. Female patients with a positive pregnancy test or who are currently lactating. 10. Patients who are taking medications that are known inhibitors of the CYP3A4 isoenzyme, such as ketoconazole. 11. Patients who have taken a monoamine oxidase inhibitor within 14 days before a dose of study medication. 12. Patients who are unsuitable for inclusion for any other reason, in the opinion of the investigator.