The purpose of this study is to monitor the long-term analgesic effectiveness, safety, and utility of oxymorphone ER for the relief of moderate to severe pain due to cancer.

Inclusion Criteria:

• Males or females aged > 18 years with moderate to severe pain arising from cancer (histologically and/or clinically proven) who require chronic treatment with WHO step 3 analgesics.
• Women of child-bearing potential must be using an approved method of contraception (hormone contraception, IUD, or double barrier method) and have a negative serum pregnancy test prior to entry into the study.
• Participated in study EN3202-018; the patient must have been treated with study medication and completed the exit visit to be eligible.

Exclusion Criteria:

• Experienced a serious, adverse experience during study EN3202-018 that was possible or probably related to study medication.
• Withdrew from study EN3202-018 due to an Adverse experience possibly or probably related to study medication.
• Known idiosyncratic reaction or hypersensitivity to oxymorphone.
• Inability to take oral medication for 1 week.
• Patients with ileosomy, mechanical intestinal obstruction, partial or complete gastric outlet obstruction, parlayticileus, or other conditions that might contraindicate the use of, or impair the absorption of an oral controlled-release dosage form.