Botulinum Toxin Injection for Intractable Pain in Cancer Patients With Psoas Muscle Invasion.

Muscle invasion (MI) in patients with far-advanced cancer is often accompanied with pain. Conventional treatments used for pain relief may be associated with several side effects. We describe two cases of botulinum toxin injection (BTI) for relieving intractable pain in patients of far-advanced cancer having MI. The patients presented with persistent intractable pain that did not respond to conventional treatments, such as analgesic medications, epidural steroid injection, and radiotherapy. BTI relieved the intractable pain in these cases for at least 9-12 weeks without any reported side effects. We suggest that BTI can be an alternative method to relieve intractable pain associated with MI in patients with far-advanced cancer.