RESUMEN
OBJECTIVE: To assess the effectiveness of a single dose of radio therapy (8 Gy vs. 6 Gy) plus zoledronic acid in cancer patients with bone metastases in treating pain; quality of life, time to onset of skeletal events and functional status. MATERIAL AND METHODS: A total of 139 patients from 22 Spanish hospitals were randomly assigned to: Group A, administered a single dose of 8 Gy+zoledronic acid (4 mg iv, in 15-min infusions), and Group B, administered a single dose of 6 Gy+zoledronic acid (4 mg iv, in 15-min infusions). The main variable was pain, which was assessed with the Visual Analogue Pain Scale (VAS) in supine, seated and standing positions. RESULTS: There was a total of 118 patients for intention to treat (n=67 in Group A and n=51 in Group B). The most frequent primary neoplasms were the lung (29.66%), prostate (22.03%) and breast (21.19%). Sixty patients were analysed per protocol, n=34 in group A and n=26 in group B. Improvements were observed in the VAS scores for pain in all three positions. The mean time to onset of the event was greater (p=0.0211) in Group A than in Group B (122 vs. 81.62 days). Functional status improved in Group A, and quality of life improved in both groups. CONCLUSION: The two groups achieved similar levels of pain control in supine, seated and standing positions. Quality of life also improved in both groups. However, the higher dose (8 Gy dose) in combination with zoledronic acid is associated with a longer period without skeletal events.