An Open Label Study to Evaluate Safety, Tolerability and Clinical Utility of ULTRACET® (37.5mg Tramadol Hydrochloride/325mg Acetaminophen) for the Treatment of Breakthrough Pain in Cancer Patients

Inclusion Criteria:

* Patients with a histologically, radiologically or haematologically confirmed malignancy whose pain is judged by the investigator to be caused by the malignancy
* Patients must have been on a stable daily dose of weak opioids or strong opioids for at least 72 hours prior to the start the study and must remain at the same dosage for the duration of the study
* Patients must have a VAS (Visual analog scale) \>=40mm

Exclusion Criteria:

* Patients who have taken either morphine with daily dose more than 120mg or Fentanyl with daily dose more than 50ug/hr
* Patients with significant abnormalities in hepatic or renal function which would, in the opinion of the investigator, prevent the patients involvement in the study
* Patients with significant clinical abnormalities in CNS, respiratory or cardiovascular function, which in the investigators judgement prevents participation in the study
* Patients who have taken antidepressants or anti-epileptic drugs, sedative hypnotics, selective serotonin reuptake inhibitor, short-acting analgesics, topical medications and anesthetics and/or muscle relaxants when taking Tramadol/Acetaminophen