Potentiel thérapeutique de la mélatonine dans la prise en charge de la pathologie cancéreuse

Exploring the Mechanical Perspective of a New Anti-Tumor Agent: Melatonin

Melatonin is a serotonin-derived pineal gland hormone with many biological functions like regulating the sleep-wake cycle, circadian rhythm, menstrual cycle, aging, immunity, and antioxidants. Melatonin synthesis and release are more pronounced during the night, whereas exposure to light decreases it. Evidence is mounting in favor of the therapeutic effects of melatonin in cancer prevention, treatment and delayed onset in various cancer subtypes. Melatonin exerts its anticancer effect through modification of its receptors such as melatonin 1 (MT1), melatonin 2 (MT2), and inhibition of cancer cell proliferation, epigenetic alterations (DNA methylation/demethylation, histone acetylation/deacetylation), metastasis, angiogenesis, altered cellular energetics, and immune evasion. Melatonin performs a significant function in immune modulation and enhances innate and cellular immunity. In addition, melatonin has a remarkable impact on epigenetic modulation of gene expression and alters the transcription of genes. As an adjuvant to cancer therapies, it acts by decreasing the side effects and boosting the therapeutic effects of chemotherapy. Since current treatments produce drug-induced unwanted toxicities and side effects, they require alternate therapies. A recent review article attempts to summarize the mechanistic perspective of melatonin in different cancer subtypes like skin cancer, breast cancer, hepatic cancer, renal cell cancer, non-small cell lung cancer (NSCLC), colon oral, neck, and head cancer. The various studies described in this review will give a firm basis for the future evolution of anticancer drugs.

[To test the impact of hypnotherapy upon immunity and circadian rhythms among palliative cancer patients: a promising goal?]

Epidemiological and clinical researches in the borderline domain between psychology and cancer have produced consequent results, despite the large variety of employed approaches and aimed goals: these results permit to define domains where new investigations still appear promising. If randomized prospective controlled trials that test the impact of psychosocial interventions, constitute to our mind a strategy that must not be bypassed, a special attention should be focussed on the following topics: 1) it seems necessary to add to standard goals (survival and quality of life) the evaluation of the impact on immunity and main biological rhythms (circadian and ultradian). Specific questionnaires should be included (pain, sleep, mood, self-esteem, life events...) and others may need to be developed or adapted (sexuality, spirituality, coping with death); 2) among types of psychosocial management, hypnosis and/or learning of self-hypnosis appears to be a modality of choice since some results have already been obtained on immune pathologies and also on cancer. Mixed to an approach of clinical psychology, such a management could arouse behavior changes toward pathology but also promote an improvement of biological rhythms (action on sleep...) and perhaps, by the way, an immune rebound; 3) on a methodological point of view, trials cannot be double-blind. The effort must then concern sample sizes, that were often insufficient in many trials, but also targeted populations: palliative cancer patients with a good performance status seem more relevant for this type of investigation, since psychosocial interventions usually improve quality of life.