A Study to Compare the Titration Efficacy and Safety of Control-released Oxycodone and Immediate-released Oxycodone in Patients With Moderate to Severe Cancer Pain

Inclusion Criteria:

1. Cancer patients aged 20 years old and over
2. Patients with background cancer pain more than or equal to NRS 4 during previous 24 hours, or receive more than or equal to 3 times/day for breakthrough pain medication management
3. ECOG ≤ 2
4. Opioid-naive patients who are not administrated any strong opioid for at least one month prior to the index treatments, who currently with poor pain control and intended to be treated for pain relief with strong opioids. The FDA identifies opioid-naive as who not receiving the following treatment for a week or longer of strong opioids:

1\) ≥ 60 mg of morphine daily 2) ≥25 mcg transdermalfentanyl/hour 3) ≥ 8 mg of oral hydromorphone daily or 4) an equianalgesic dose of another opioid

5\) Patients who will not be treated with radiotherapy within 7 days prior to randomization and during study

6\) Patients who need chemotherapy, long term administration of hormone, targeted therapy, or bisphosphonates therapy should undergo a stable anti-tumor therapy prior to randomization.

7\) Patients or his/her caregivers who are able to fill out the diary and questionnaire forms

Exclusion Criteria:

1. Patients diagnosed with non-cancer pain or unexplained pain
2. Patients suffered with post-op pain
3. Patients who cannot be applicable for oral administration
4. Patients who have severe constipation defined by CTCAE grade 3 and above
5. Patients with any disease that may easily lead to respiratory depression
6. Monoamine oxidase inhibitor (MAOI) was administrated one week before randomization
7. There are abnormal lab results, with obvious clinical significance, such as the creatinine ≥ 2 fold of upper limit of normal value, or ALT or AST ≥ 2.5 fold of upper limit of normal value (≥ 5 fold, to the patients with liver metastasis or primary liver cancer), or liver function of Child C grade
8. Patients who have potential risk for surgical operation, which may lead to gastrointestinal stenosis, blind loop or gastrointestinal obstruction; or patient is unable to effectively absorb oral medication through gastrointestinal tract
9. Patients who are drug or alcohol abuse
10. Patients with moderate to severe psychiatric problems
11. Patients who have hypersensitivity to oxycodone
12. Patients who are pregnant or lactating
13. Patients who are clinically unstable or have a life expectancy of less than three months making completion of the trial unlikely