Efficacy of neuromodulation techniques (TMS and tDCS) in cancer pain management: A systematic review.

The global incidence of oncological disease is rising, driven by increased longevity and greater exposure to carcinogens. Pain remains one of the most prevalent and disabling symptoms among cancer patients, requiring urgent evaluation and treatment. However, selecting an effective therapeutic approach remains a challenge. Neuromodulation techniques such as Transcranial Magnetic Stimulation (rTMS) and Transcranial Direct Current Stimulation (tDCS) have shown promise in managing chronic pain across various conditions, but evidence in the oncological context is still limited. This study systematically reviewed the effects of rTMS and tDCS on cancer pain management. A literature search was conducted in PubMed, Web of Science, Scopus, ProQuest, and CENTRAL, following PRISMA guidelines, yielding 657 potentially relevant studies. Quality assessment was performed using the Joanna Briggs Institute (JBI) checklist. Eight randomized controlled trials from four countries were included, involving 349 patients: three employing rTMS and five using tDCS. The studies examined diverse patient groups, cancer types, and neuromodulation protocols, producing mixed but generally short‑term reductions in pain. Indirect evidence suggests that rTMS may induce faster but shorter‑lived analgesia, whereas tDCS may be associated with modest persistence when delivered in repeated sessions. Overall, the findings provide preliminary evidence that non‑invasive brain stimulation techniques may contribute to cancer pain management. Future research should optimize stimulation parameters, conduct direct comparisons, and explore integration with pharmacological and behavioral strategies to enhance long‑term effectiveness.