Generalised cancer, a function of the relative brainsize.

The prevalence of spontaneous, generalised malignant tumours in 10 mammalian species was compared with their relative brain sizes (RBS), and the outcome, supported by the statistical significance, argues for the psyche as a contributing factor in cancer. The variation in life spans and metabolism of the species was subsequently equalised and applied to the statistics. The mediators are deductively suggested to be the sympathetic nervous system (SNS) and its neurotransmitter noradrenaline, which may exert a direct, lethal effect on tumours. The strain on the autonomous nervous system (ANS), dispersed throughout the brain, is assumed to be increasing with the increasing ratio of neurones belonging to 'receiving, processing and conscious areas' (RPCA), where the extension or density of ANS may be adapted to the dimensions of the body it supplies.Interference in neocortex and other parts of the brain, partly stress-induced, might cause dysfunction of ANS, which aggravates with a proportional increase of RBS.