Transcranial Direct-current Stimulation (tDCS) Efficacy in Refractory Cancer Pain.
Transcranial Direct-current Stimulation (tDCS) Efficacy in Refractory Cancer Pain.
Pain is a common symptom in palliative care cancer patients and is often insufficiently
 relieved. The 2010 INCA report showed that France is not an exception to this worldwide
 observation (synopsis of the 2010 national survey). This report shows that pain is the
 symptom that these patients fear the most and that it dramatically impacts their quality of
 life. These patients may experience nociceptive pain related to stimulation of sensory nerve
 endings by the tumour. When tumour resection is impossible, a symptomatic analgesic treatment
 is generally proposed, mainly consisting of administration of opioid analgesics. At high
 doses, this treatment induces adverse effects, especially drowsiness and psychomotor
 retardation that impair the patient's quality of life.

 They may also experience neuropathic pain, secondary to anatomical lesions or functional
 impairment of nerve structures (peripheral nerves or cerebral or spinal tracts) related to
 repeated surgical procedures and/or radiotherapy. This type of pain may respond to
 antiepileptic or antidepressant drugs. At high doses, these treatments also induce adverse
 effects fairly similar to those observed during treatment of nociceptive pain. As these two
 types of treatment often need to be coprescribed, these patients frequently present an almost
 permanent state of drowsiness at the end of life, preventing all normal activities of daily
 living.

 In recent years, noninvasive brain stimulation (NIBS) techniques (transcranial magnetic
 stimulation (rTMS) or transcranial direct-current stimulation (tDCS)) have been successfully
 used to treat chronic pain. It was shown that these NIBS techniques can improve pain in
 cancer patients in the palliative care setting.
tDCS appears to be more suitable than rTMS for the treatment of palliative care patients, who
 are often difficult to mobilize, as tDCS can be delivered at the patient's bedside and
 possibly even at home, which is not the case with rTMS. tDCS also appears to be rapidly
 effective (after 5 sessions) in the context of cancer pain, and this effect lasts longer than
 that of rTMS.

 The proposed treatment of refractory cancer pain by tDCS in palliative care patients is a new
 treatment modality that is well adapted to hospitalised patients. Each patient will receive
 20 minutes of transcranial direct-current stimulation daily for 5 consecutive days.

 One arm will receive active stimulation and the control arm will receive sham stimulation.
 Patients and investigators will be blinded to the type of tDCS.

 By improving the patient's activities of daily living, this treatment will enable the patient
 to return home under good conditions for both the patient and the caregivers. This treatment
 can also be continued at home. This strategy is consistent with current guidelines in this
 field, in which the priorities are improvement of quality of life, return home and decreased
 workload for caregivers.
Inclusion criteria

 1. Patient with a confirmed cancer at a palliative stage

 2. Pain whose mean intensity is greater than or equal to 4/10 in the 48 hours preceding
 inclusion

 3. Pain present on a daily or almost daily basis (at least 4 days out of 7)

 4. Pain that has been present for at least 48 hours before inclusion

 5. Patients aged 18 or over

 6. Patients who can be followed for the duration of the study (i.e. 3 weeks)

 7. Patients affiliated to a health insurance plan or entitled

 8. Life expectancy estimated at more than 3 weeks

 9. Agreeing to participate in the study and having signed an informed consent

 Exclusion criteria

 1. Inability to self-assess pain and complete self-questionnaires

 2. History of head trauma or neurosurgical injury

 3. Symptomatic intracranial hypertension (HTIC)

 4. Uncontrolled epilepsy

 5. Impossibility to correctly positioning the medical device

 6. Abuse of drugs or psychoactive substances, at the discretion of the investigator

 7. Current major depression or psychosis

 8. Pregnant or breastfeeding woman

 9. Patient already included in a research protocol on pain

 10. Patient under legal protection

 11. Absence of affiliation to a social security scheme

 12. Specific contraindication to tDCS (intracerebral metal implant)

 13. Patients deprived of liberty

 14. Patients undergoing psychiatric care.