A neuropathic pain component as a predictor of improvement in pain interference after radiotherapy for painful tumors: A secondary analysis of a prospective observational study

Abstract

Background and purposeWe previously demonstrated that patients with a tumor-related neuropathic pain component were more likely to experience a pain response after radiotherapy (RT) than those without. It is unknown whether the presence of a neuropathic component also favorably influences pain interference. In a secondary analysis of our previous prospective observational study, we investigated if the presence of a neuropathic component of the index pain caused by the irradiated tumors predicts greater reduction in pain interference. Material and methodsFor patients scheduled for RT for painful tumors, Brief Pain Inventory data were collected at initiation of RT and 1, 2, and 3 months thereafter. Multivariable linear regression analyses were performed to investigate the effects of the presence of a neuropathic component on the changes in pain interference scores (i.e., follow-up minus baseline). We used 10 covariates as potential confounders. ResultsOf the 302 analyzable patients, 93 (31%) were diagnosed as having a neuropathic component of the index pain. Multivariable linear regression analyses revealed that all the point estimates of regression coefficients at 1-, 2-, and 3-month follow-up were negative values; some were statistically significant. At 2-month follow-up, patients with a neuropathic component experienced greater reductions in their pain interference scores for walking ability (p = 0.048), normal work (p = 0.021), sleep (p = 0.001), and enjoyment of life (p = 0.010) than those without it. ConclusionsThe presence of a neuropathic pain component predicted a greater reduction in pain interference after RT. Patients with neuropathic tumor-related pain should be offered the option of receiving palliative RT.