Bicentre, randomized, parallel-arm, sham-controlled trial of transcranial direct-current stimulation (tDCS) in the treatment of palliative care patients with refractory cancer pain

Analgesic efficacy of non-invasive neuromodulation techniques in chronic cancer pain: a systematic review

PURPOSE

Chronic pain remains one of the most frequent and disabling symptoms of cancer, arising from tumors and/or treatments, and is poorly controlled in 40% of patients. Non-invasive brain stimulation (NIBS) is now widely recommended in drug-refractory neuropathic pain, but its effectiveness in chronic cancer-related pain remains unknown. A few observational studies and randomized controlled trials (RCTs) have assessed the effectiveness of NIBS on pain in this population.

METHODS

A systematic review of neuromodulation studies on patients with chronic cancer-related pain involving transcranial direct currents stimulation (tDCS) or repetitive transcranial magnetic stimulation (rTMS) was conducted to estimate the analgesic efficacy, safety and feasibility in clinical routine.

RESULTS

Eleven publications (N = 298 patients) were included and analyzed. For tDCS, three RCT had a moderate effect size of 0.7 [0.6; 0.9] on a rating scale (0-10), and two case reports showed a significant decrease of pain intensity on average by -4.25 ± 0.36 points. The rTMS provided similar pain relief, with two RCTs showing a large effect size of 0.9 [0.7; 1.1], two observational study studies reporting a significant pooled effect on pain intensity (-0.9 [-1.6; -0.1] and -2.3 [-3.3; -1.3]), and two case reports where pain was reduced on average by -4.75 ± 0.36 points. None of these studies reported serious adverse events, and discontinuations of treatment were associated with cancer complications.

CONCLUSIONS

NIBS appears to have an analgesic effect in cancer-related pain. However, due to the high heterogeneity of pain conditions, placebo-controlled trials with larger and homogeneous patient cohorts are required to confirm these promising results.

The Application of tDCS to Treat Pain and Psychocognitive Symptoms in Cancer Patients: A Scoping Review

Background

The use of transcranial direct current stimulation (tDCS) to modulate pain, psychological aspects, and cognitive functions has increased in recent years. The present scoping review aims to investigate the use of tDCS in cancer patients and its significant impact on psychocognitive and pain related symptoms.

Methods

From the earliest available date to June 2023, a comprehensive search was conducted in three electronic scientific databases-PubMed, Scopus, and Embase-and other supplementary sources. Ten relevant studies were identified and included, comprising single case studies, randomized controlled trials, pilot studies, and one retrospective study. PRISMA guidelines for scoping reviews were followed.

Results

These studies investigated the use of tDCS to improve pain and psychocognitive aspects in patients with various types of cancer, including breast, oral, bladder, lung, pancreatic, head and neck cancer, hepatocellular carcinoma, and meningioma. Overall, the results suggest that tDCS has shown efficacy in relieving pain, reducing anxiety and depression, and improving cognitive function in cancer patients.

Conclusion

Due to the limited number and high heterogeneity of the existing literature in this field, more investigation and the establishment of standardized protocols would be required to obtain more conclusive evidence.

Cancer Pain and Non-Invasive Brain Stimulation-A Narrative Review

Background and Objectives: Pain is the most prevalent symptom in cancer patients. There is a paucity of data regarding non-invasive brain stimulation (NIBS) for the treatment of chronic pain in patients with cancer. The purpose of this article is to review the techniques of NIBS and present the published experiences of the oncological population. Materials and Methods: Databases including MEDLINE, Scopus, Web of Science, and the Cochrane Library were searched for articles on cancer patients with pain that was managed with non-invasive brain stimulation techniques. We included articles in English that were published from inception to January 2023. As studies were limited in number and had different designs and methodologies, a narrative review was considered as the best option to integrate data. Results: Four studies focusing on transcranial magnetic stimulation, six articles on transcranial direct current stimulation, and three articles regarding cranial electric stimulation were found and reviewed. Conclusions: Data are limited and not robust. Further studies in this field are required. Guidelines on NIBS for non-malignant chronic pain conditions provide good premises for cancer-related chronic pain.