Why the incidence of cancer is increasing: the role of 'light pollution'.

At present, cancer is responsible for almost half of all deaths among women 45-64 years of age, and about 30% of all deaths among men in the same age group (1). This high rate represents a marked increase from the end of the last century (2), and it probably has a multifactorial etiology. Air pollution, smoking, diet, alcohol, occupational exposures and stress are all considered as possible etiologic and risk factors (3). We put forward a hypothesis that one of the most important etiologic factors in the rapid growth rate of cancer is the change of light exposure that took place in the last 100 years, especially in the developed countries. Increased light exposure acting through the pineal gland reduces melatonin production, thereby diminishing the non-specific oncostatic effects of the pineal gland.