Morphine as the First Drug for the Treatment of Cancer Pain

After approval of the Ethics Committee and signing the consent, a prospective randomized study was performed in patients ≥ 18 years, with locally advanced cancer and / or metastases, and pain intensity ≤ 6. There were excluded patients with difficulty maintaining clinical follow-up, cognitive impairment and prior treatment with opioids. G1 patients were treated according to the guidelines of the WHO analgesic ladder starting at the first step, with paracetamol 1g each 6 hours, maximum dose of 4 g/ day, in the second, codeine (30 mg each 4 hours , maximum dose 360 mg / day and morphine 10 mg each 4 hours in the third step. Patients in G2 started with morphine 10 mg each 4 hours. Adjuvant drugs have been associated when indicated. According to the intensity of pain the medication was changed according to analgesic ladder in G1 patients and adjusted the dose in G2. The cancer therapy as palliative radiotherapy, chemotherapy or hormone therapy was performed by the oncologist.

There were evaluated: pain intensity every 2 wk. by visual analogue scale (VAS), quality of life every 4 wk. through the brief questionnaire of quality of life of the WHO 19, satisfaction with treatment, physical capacity measured by the index of Eastern Cooperative Oncology Group (ECOG) 20, and the need for additional analgesics. Adverse effects were recorded. The study was considered completed with the patient's death or three months of follow-up.

To calculate the minimum sample size was used the program BioEstat 2.0. There were used as reference means and standard deviations values of study with a similar method 5. Considering a confidence level of 95% study power of 80% of the minimum sample of 30 patients for each group, totaling 60 patients. For the statistical analysis was used GraphPad Prism ®. There was used the Student t test for age, weight, height, chi-square test for patient satisfaction, need for complementation, and adverse effects, and Mann-Whitney test for pain intensity, quality of life and physical capacity. A p value of ≤ 0,05 was considered significant. The resultas were expressed as mean ± DP.