The effectiveness of botulinum toxin A for persistent pain at the pectoral region after breast cancer treatment: Randomized controlled trial

Abstract

Upper limb pain after breast cancer treatment is a common and difficult to treat problem. The aim of the present study was to investigate the effect of a single botulinum toxin A infiltration in the pectoralis major muscle in addition to a standard physical therapy program for treatment of persistent upper limb pain in breast cancer survivors. Fifty breast cancer patients with pain participated in a double-blinded randomized controlled trial. The intervention group received a single botulinum toxin A (BTX-A) infiltration. The control group received a placebo (saline) infiltration. Within one week after the infiltration, all patients attended an individual physical therapy program (12 sessions) during the first 3 months and a home exercise program up to 6 months after infiltration. The primary outcome was change in pain intensity at the upper limb (Visual Analogue Scale [VAS] [0–100]) after 3 months. Secondary outcomes were prevalence rate of pain, pressure hypersensitivity, pain quality, shoulder function and quality of life. Measures were taken before the intervention and at 1, 3 and 6 months follow-up. No significant difference in change in pain intensity after 3 months was found (mean difference in change of 3/100; 95% CI: −13 to 19). From baseline up to 6 months, a significantly different change in upper limb pain intensity was found between groups in favor of the intervention group (mean difference in change of 16/100; 95% CI: 1 to 31). A single botulinum toxin A infiltration in combination with an individual physical therapy program has been found to significantly decrease pain intensity at the upper limb in breast cancer survivors up to 6 months. However, the effect size was not clinically relevant and no other beneficial effects were found.