Methadone and neuropathic cancer pain subcomponents: a prospective cohort pilot study.

UNLABELLED: Forty per cent of cancer pain associate neuropathic and nociceptive pain simultaneously, and refractory pain affects 15% of cancer pain. Methadone is an effective opioid in treating nociceptive pain and could have an effect on neuropathic pain. Uncertainty remains on its effects on the different subcomponents of neuropathic pain.

OBJECTIVES

To identify which subcomponents of neuropathic cancer pain are addressed using methadone.

METHODS

An observational prospective cohort study of palliative care inpatients after rotation for refractory neuropathic cancer pain. Pain intensity was assessed weekly for 28 days, using a Visual Analogue Scale (VAS) and the Neuropathic Pain Symptom Inventory (NPSI).

RESULTS

Forty-eight patients were included and 17 completed the 28 days follow-up. VAS pain rating decreased by at least 20 mm in 47% of patients and the pain intensity was significantly lower at day 28 with 53% of patients with a VAS inferior to 4 (p<0.001). The pressure/squeezing component (NPSI score) decreased by more than 2 points in 50% of patients.A linear regression showed allodynia and pressure/squeezing were responsible for the largest part of the overall alleviation of pain (p=0.01).

CONCLUSIONS

Methadone could significantly improve neuropathic pain through a targeted effect of allodynia and its pressure/squeezing component.