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

To evaluate whether age is a predictor of pain response after radiotherapy for painful bone metastasis (BM).

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).

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.

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.