It is proposed that the prerequisites for a low risk to major cancers - breast, colon, lung, prostate, melanoma (as, for example in Africans, Chinese and Japanese) - include upregulated hypothalamic dopamingergic activity compared to depressed noradrenergic/thyrogenic function and raised vagal tone, and a neuroendocrine constellation that promotes improved immune efficiency and is inimical to the onset of aversive cell responses. Since the integrity of these tissues is regulated by hypothalamic-hypophyseal hormones, under tonic dopaminergic inhibition, cancers are potentially preventable as long as dopaminergic integrity is maintained, or the decline in ageing is slowed. Evidence for the impact of upregulated dopamine on tumour prevention includes: (1) a reduced (40%) rate of colonic cancer in exercise-trained ageing subjects: (2) reduced expected rates of lung/colon cancers, and skin tumours in prolonged post-menopausal oestrogen replacement; (3) the virtual suppression of all cancers during pregnancy (when dopamine synthesis increases); (4) the low rate of bronchogenic carcinoma correlates with reduced enzymatic conversion of dopamine to noradrenaline; and (5) neuroblastoma (specifically dopamine dysregulated tumour) regresses spontaneously on dopamine normalization. Similar tumour reduction is anticipated by controlling the intake of calories. The subtlety of the switch to upregulated dopamine, the speed of translation at the cellular level and the sustainability of responses as long as the initiating stimulus persists (as exposed by pregnancy), underline the plasticity of the neuroendocrine mechanism and ease of manipulation. Long exposure to environmental iodine deficiency, as seen for example in Africans and Chinese, reveals a crucial dopamine-thyroid action that slows cell timing mechanisms. The common neurohormonal basis identified for the prevention of human cancers has practical application, with reasonably assured positive results.
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