title: Geographic mappings of colorectal cancer rates: a retrospect of studies, 1974-1984.
abstract: Geographic mapping of colorectal cancer rates revealed areas with high rates as well as areas with low rates. Comparisons between high-rate areas and areas deficient in selenium led to animal experiments that showed that selenium could reduce chemically induced intestinal tumors. A low-rate area was found to be geochemically unique with soil and water rich in potassium. This led to a series of studies indicating that elevated intracellular potassium reduces cancer risks, while elevated intracellular sodium increases the risks. Variance-reducing techniques and methods for statistical evaluation of clusters were obtained as spinoff results.
mesh_terms: D003110:Colonic Neoplasms / Q000453:epidemiology* / Q000209:etiology / Q000401:mortality; D004032:Diet; D005260:Female; D005843:Geography; D006801:Humans; D008297:Male; D009316:National Institutes of Health (U.S.); D012004:Rectal Neoplasms / Q000453:epidemiology* / Q000209:etiology / Q000401:mortality; D012189:Retrospective Studies; D012737:Sex Factors; D014481:United States