Evaluation Prospectively the Level of Reduction in Cognitive Functions of Cancer Patients Who Are on Active Oncology Treatments and Use Cannabis. The Second Goal is to Identify High-risk Groups for Cognitive Impairment Due to Cannabis Use.

Cannabis sativa is one of the most ancient psychotropic drugs known to humanity. Although most Western countries have outlawed the use of cannabis according to the UN Convention of Psychotropic Substances, an increasing number of states in the USA, Canada and several European countries allow the medicinal use of cannabis subject to a doctor's recommendation. In oncology, the beneficial effects of treatment with the plant or treatment with medicine produced from its components are related to symptoms of the disease: pain, nausea and vomiting, loss of appetite and weight loss. There is only partial clinical evidence of the efficacy of cannabis for these indications. In Israel, according to Ministry of Health regulations, permission to use medicinal cannabis for oncology patients can be given for two indications: to relieve disease-related symptoms in advanced disease or during chemotherapy treatment to reduce side effects. The indications are very wide and allow a great deal of freedom for the physician's decisions, but also cause high demands for cannabis from patients. The cannabis plant and the synthetic drugs based on the plant are considered to be medically safe. Most of the adverse effects are related to the fact that the plant and the drugs are psychoactive. Among the effects named were dizziness, euphoria, difficulty concentrating, disturbances in thinking, memory loss, and loss of coordination. Recently, we published the results of a prospective, observational study evaluating the medical necessity for medicinal cannabis treatment in cancer patients on supportive or palliative care. No significant side effects, except for memory lessening in patients with prolonged cannabis use (p=0.002), were noted. Chemotherapy-related cognitive impairment (CRCI) is a phenomenon of cognitive decline that patients may experience during or after chemotherapy. Memory loss and lack of concentration and attention are the most frequent symptoms encountered. Evidence suggests that CRCI is of significant concern to patients and has become a major quality-of-life issue for survivors, with estimates of its frequency ranging from 14-85% of patients. The influence of cannabis use on cognitive functions of oncology patients has never been tested. Theoretically, the combination of chemotherapy and cannabis can cause severe reduction in cognitive functions in additive or synergistic ways. However, this hypothesis, too, has never been tested, although the number of patients using cannabis during chemotherapy treatments in Israel and in other Western countries is growing. Goals of current research: The main goal of the study is to evaluate prospectively the level of reduction in cognitive function of cancer patients who are on active oncology treatments and use cannabis, comparing to a group of patients without cannabis treatment. The second goal is to identify high-risk groups for cognitive impairment due to cannabis use. Patients and Methods: The study will be comprised of a cannabis user group that will include patients who will come for guidance sessions before being issued with a cannabis license and a control group of patients on active oncology treatments, meeting the same inclusion and exclusion criteria (except for cannabis use), and willing to complete the same pack of questionnaires and cognitive tests at the same three time points. All patients will sign an informed consent form. The study includes questionnaires on quality of life (EORTC-Q30), anxiety, depression (HADS) and fatigue (BFI), and cognitive tests (MoCA, DSST, Digital Finger Tapping) administered by the nurses who give guidance on cannabis according to the patient's language (Hebrew, Russian or Arabic). The nurses will have a short guidance course on "how to do cognitive tests" and a monthly meeting with a neuropsychologist to test the quality of the cognitive tests. The questionnaires and cognitive tests will be done on the day of entering the study (T0) and after 3 (T3) and 6 months (T6). The patients will be asked not to use cannabis in the 12 hours before the interviews after 3 and 6 months. Sample size: The sample size was built to show a difference of 1.1 points in the MoCA test (half the SD for the normal population) between two groups after three months of cannabis use. The number of patients needed with a power of 80%, β≤0.05 and SD=3.1 (the SD for mild cognitive impairment in the MoCA test) is calculated at 42 patients in each group (total 84 patients). Due to an expected drop-out of 20%, the number of patients to be included in the study is 101.

Sex

All

Minimum age

18 Years

Maximum age

120 Years

Inclusion Criteria:

1. Age \>18 years
2. Histological or cytological documentation of malignancy
3. Chemotherapy treatment
4. Life expectancy of at least 6 months
5. Able to sign informed consent.

Exclusion Criteria:

1. Brain tumors or CNS metastasis
2. Past cannabis use,
3. Known cognitive diseases such as Alzheimer's disease or other dementias