The Kinetics of Endocannabinoids in Patients With Chemotherapy Induced Peripheral Neuropathy by Using Medical Cannabis.

Inclusion Criteria: * 1\. Age above 18 years and below 80 years old. 2. Pathology of Breast or GI malignancies. 3. Treatment with Taxans (Taxol/ Taxotere) or Oxaliplatin for adjuvant treatment or metastatic disease. 4\. Estimated life expectancy ≥ 6 months. 5. Performance status ≤1 (ECOG classification). 6. Sign of written informed consent. 7. CIPN is examined during the chemotherapy treatment DN4 score must be above 4 (and by physician decision) for more than one week. 8\. Patient with adequate liver/renal function at screening as described: * Creatinine clearance \>30 ml/min as calculated by Cockcroft-Gault Equation. * Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤2.5 x ULN. 9. Patients who suffer from pain although using a stable analgesic treatment' at least 14 days before entering the trial (no limitation for the use of the analgesic). 10\. Patient possessed a valid license from the Israeli Ministry of Health to receive medicinal cannabis. 11\. Patient is able and willing to comply with study requirements. 12. Patient agrees to use only medical cannabis provided by study team until the end of study period. 13\. Patient has not undergone major surgery in the month prior to the study start. 14\. Patient agrees not to participate in other interventional clinical trial during the study participation. Exclusion Criteria: * 1\. Use of cannabis or synthetic cannabinoids in the last two weeks (urine test for cannabinoids are positive). 2\. Patient with known or past substance abuse. 3. Patients with major psychiatric disorders (e.g. schizophrenia, dementia, and intellectual disabilities). 4\. Patients with first degree siblings under the age of 30 years old with psychiatric disorders. 5\. Patients with uncontrolled diabetes mellitus, cardiovascular, or convulsive disorders according to investigator. 6\. Patients with sensitivity to cannabis or cannabinoids. 7. Patients with known neuropathic pain due to diabetes or other diseases. 8. Patients with severe respiratory disease. 9. Patients with brain metastases or brain tumors may participate if completed radiotherapy treatment at least 14 days prior to signing the informed consent and last imaging did not show any worsening. 10\. Female subjects who are pregnant, lactating, or want to get pregnant during the study period and one month following the study. Male subjects who want their partner to get pregnant during the study period and one month following the study. 11\. Females of childbearing potential or males whose partners with childbearing potential and did not use adequate contraceptives 28 days prior to study start or during the study. 12\. Other life-threatening medical conditions that disqualify the patient from participating in the study, according to the Primary Investigator's judgment. 13\. Anticipated alcohol or barbiturate use during the study period. 14. Participation in other clinical trials during the last month. 15. Subjects who are using one of the following medications: opiates (Primidone, Phenobarbitol, Arbamazepine, Rifampicin, Rifabutin, Troglitazone and Hypericum perforatum). 16\. Patient who has undergone a major surgery a month prior to study start.