Analysis of predictors of pain response in patients with bone metastasis undergoing palliative radiotherapy: Does age matter?

INTRODUCTION: To evaluate whether age is a predictor of pain response after radiotherapy for painful bone metastasis (BM). METHODS: Between June 2010 and June 2014, 204 patients with BM undergoing palliative radiotherapy participated in a multicentre prospective study. Patients completed the Brief Pain Inventory (BPI) to rate the intensity pain (from 0 to 10) at baseline and 4 weeks after radiotherapy. To determine which variables predicted pain response and particularly whether age is a predictor, logistic regression analysis was used. Baseline variables considered were: age (≤65/66-75/>75 years), sex, Eastern Cooperative Oncology Group performance status (0-1/≥2), pretreatment pain score (≤4/5-7/≥8), radiotherapy (single/multiple fraction), primary tumour location, visceral metastases (yes/no), concomitant systemic chemotherapy and bisphosphonate use (yes/no). RESULTS: Pain response was assessed in the 128 patients who completed BPI pretreatment and at 4 weeks after radiotherapy. According to univariate analysis, pain response was better in over 75-year-olds than younger patients: (OR, 3.2; 95% CI, 1.1-9.1; P = 0.031). Response was better in patients receiving multiple fractions rather than a single fraction of 8 Gy (OR, 2.8; 95% CI, 1.2-6.1; P = 0.01), and in patients with a pretreatment pain score ≥8 vs ≤7 (OR, 2.4; 95% CI, 1.1-5.0; P = 0.017). No other variables were significant. Multivariate analysis showed that treatment schedule (OR, 3.4; 95% CI 1.4-7.9; P = 0.004) and pre-radiotherapy pain score (OR, 2.8; 95% CI 1.3-6.3; P = 0.009) were the only independent predictors of pain response. CONCLUSION: All patients with painful bone metastasis should be referred for palliative radiotherapy to relieve the pain regardless of age. Therefore, an older age should not be a reason to withhold palliative radiation treatment.