Fatigue is a symptom most commonly associated with the diagnosis of cancer. Fatigue often appears before the diagnosis of cancer, is increasing during treatment with chemotherapy and persists for years after treatment in more than 35% of patients. Fatigue is the earliest and most important symptom described by cancer patients. Its prevalence in cancer chemotherapy patients is between 70 and 100%. Fatigue is more common to cancer patients and to the general population or other types of patients. Typically described as a lack of energy associated with mental disorders, fatigue related to cancer can be extremely debilitating. The causes are many, mainly including the cancer itself, side effects due to treatment, sleeplessness due to pain, anxiety or depression. The cancer-related fatigue has a negative and significant direct impact on all aspects of the patient's quality of life, especially the physical, social and behavioral. Despite the availability of certain treatments and the advanced biomedical research, fatigue remains an inevitable consequence of cancer and its treatment.

The therapeutic use of natural light in medicine dates back to the late nineteenth century. Its remarkable effect on the stimulation of the immune system and fight against infections caused the development of the first therapy techniques (also called luxthérapie) awarded in 1903 by the Nobel Prize in medicine and physiology. Light plays a fundamental role in the regulation of circadian rhythms and homeostatic. The mechanism of action passes through a path "non-visual" involving melanopsin ganglion cells located in the retina. Activation of the pineal gland (epiphysis) by melanopsin cells allows transduce information "shadow and light" in melatonin synthesis from serotonin. Today, the effectiveness of the therapy is well established for treating fatigue-related disorders such as chronic fatigue, seasonal depression or seasonal or non-certain sleep disorders and in which the melatonin metabolism is disturbed. Light therapy, by its mechanism of action, allows reprogramming "of the biological clock and improved synchronization of circadian rhythms.

Hypotheses

Some studies have shown an inverse relationship between cancer-related fatigue and the time of exposure to natural light for cancer patients. This association suggests the existence of a vicious circle of side effects of chemotherapy (physical fatigue and moral), itself causing a decrease in outdoor activity and therefore a reduction of the light exposure time natural. This results in a strengthening of the initial patient's state of fatigue. In an interesting way, vitamin D synthesized in large part due to light plays a cancer protective role], especially in the prevention and treatment of pancreatic cancer for example. Furthermore and paradoxical way, the disruption of circadian rhythms is correlated to the development and tumor progression in vitro, in vivo tumor growth and incidence of cancer in humans.

Notoriously, the direct effect of light therapy on cancer-related fatigue has been little discussed in the literature. Data obtained from a small sample of patients indicate that light therapy improves quality of life by reducing fatigue in patients with breast cancer during chemotherapy. To date, There are no data on the effects of light therapy on cancer-related fatigue in general, patients treated with chemotherapy.

The purpose of this pilot study is to evaluate the role of light therapy on cancer-related fatigue in patients during the 6 months following initiation of first-line chemotherapy.

Primary objective

To assess the effects of daily therapy on fatigue of patients with locally advanced or metastatic cancer treated with chemotherapy.

secondary objective

Evaluate the impact of daily light therapy on quality of life, pain, anxiety and depression, tolerance of chemotherapy and medico-economic benefits.

Inclusion Criteria:

• Cancer histologically or cytologically confirmed (regardless of type)
• Patient eligible for first-line chemotherapy
• Life expectancy> 3 months
• WHO PS ≤ 2
• Age ≥ 18 years
• Informed consent signed and dated
• Affiliation to a social security scheme

Exclusion Criteria:

• Macular degeneration
• Diabetic retinopathy
• Glaucoma
• untreated cataract
• Patient treated with vitamin D
• Psychiatric disorders (bipolar disorder, paranoia, schizophrenia)
• For patients with other comorbidities may indicate against-the practice of therapy: application specialist opinion (ophthalmologist or psychiatrist)