Neuropathic Pain Features in Patients with Bone Metastases

The results of previous randomised controlled trials suggest that radiation oncologists should consider the presence of neuropathic pain when they prescribe dose fractionations for painful bone metastases. Although validated screening tools for neuropathic pain features are currently available, the prevalence of such features among patients with painful bone metastases is still poorly understood. The purpose of this study was to estimate the prevalence of neuropathic pain features among patients who received palliative radiotherapy for painful bone metastases.

We conducted a cohort survey of consecutive patients who received palliative radiotherapy for painful bone metastases at St Luke's International Hospital between 2013 and 2014. Patients were prospectively assessed before radiotherapy using the validated screening questionnaire to identify neuropathic pain components in Japanese patients. Pain with neuropathic features was prospectively defined using the total score of the seven-item questionnaire and a cut-off score ≥9. The pain response was assessed 2 months after the start of radiotherapy according to the criteria defined by the International Bone Metastases Consensus Working Party.

Eighty-seven patients were assessed. Twenty-four per cent of patients (95% confidence interval: 16-35%) were diagnosed as having pain with neuropathic features. On multivariate analysis, no significant correlations were seen between neuropathic pain features and patient characteristics. Sixty-four patients (74%) were assessable 2 months after the start of radiotherapy. Overall response rates were 59% (95% confidence interval: 33-82%) in patients with neuropathic features and 55% (95% confidence interval: 40-70%) in those without such features.

A considerable proportion of the patients were proven to have bone pain with neuropathic features. Further investigations are warranted to validate symptom assessment tools in cooperation with pain distribution and image findings, and to clarify if the presence of neuropathic pain affects the response to palliative radiotherapy.