Neurostimulation for the Treatment of Cancer-Induced Pain: A Scoping Review

Cancer pain is among the most prevalent and challenging symptoms in cancer care, with up to 95% of patients with late-stage cancer experiencing moderate-to-severe pain. Conventional pharmacologic treatments, including opioids, carry risks, and patients' conditions may be refractory to medical management or have contraindications. Neurostimulation techniques, such as spinal cord stimulation (SCS), dorsal root ganglion stimulation (DRGS), and peripheral nerve stimulation (PNS), have shown promise in treating treatment-induced cancer pain. However, a comprehensive review focusing on these techniques for cancer-induced pain alone is necessary.

A comprehensive literature review was conducted using Medline, Embase, and Cochrane Library data bases, focusing on studies from 2000 onward. Inclusion criteria included interventional and observational studies reporting on SCS, DRGS, and PNS in cancer-induced pain. Studies addressing treatment-induced pain, systematic reviews, meta-analyses, and non-English studies were excluded. Data were extracted and evaluated using the Grades of Recommendation, Assessment, Development, and Evaluation system.

The search yielded 831 references, with 24 studies meeting the inclusion criteria. Sixteen studies focused on SCS, seven on PNS, and two cases on DRGS. SCS showed significant pain reduction, with an average decrease in numeric rating scale (NRS) scores from 8.0 to 2.2 over an average 8.4-month follow-up period. PNS also indicated substantial pain relief, with NRS scores decreasing from 8.29 to 3.04 over an average 5.2-month follow-up period. DRGS, although less studied, showed a reduction in NRS scores from 6.0 to 1.0 over an average 6.0-month follow-up period. SCS was associated with a significant reduction in opioid use, with average reported morphine equivalent daily dose (MEDD) change from 1152.2 mg to 739.7 mg over an average 5.0-month period, whereas PNS and DRGS had limited impact on opioid consumption, with no reported MEDD change.

Our scoping review synthesizes evidence on neurostimulation interventions for treating cancer-induced pain. Current evidence suggests that interventions such as SCS, DRGS, and PNS may provide clinically meaningful pain relief in patients with cancer-induced pain. Several studies also reported improvements in functionality and quality of life. However, the level of evidence is limited owing to the lack of prospective comparative studies, clinical and methodologic heterogeneity, and small sample sizes.