The lesion site in malignant psoas syndrome influences the cancer pain intensity.

Background: Malignant psoas syndrome (MPS) is characterized by pain and hip flexion fixation due to tumor infiltration of the iliopsoas muscle. However, the dose of opioid required to control pain varies markedly among MPS patients. As the ability to predict whether an MPS patient will need a higher opioid dose in the early period of pain control is clinically meaningful, we retrospectively evaluated the relationship between lesion site in MPS and the opioid dose required for pain control.