Abstract
The correlation between mortality rate from stomach cancer and some basic ecological factors such as average temperature, sunshine duration and mineral content of river water is studied on 46 prefectures in Japan. Peculiar geographic distribution of the death rate from stomach cancer in Japan is as already introduced by Segi and others. The river water quality is expressed as the ratio of Ca/SO4. The negative correlation coefficients of male age-adjusted stomach cancer mortality rate with yearly sun-shine duration and with Ca/SO4 ratio of river water were significant, but no correlation was found with yearly average temperature. The meaning of the significant correlation is interpreted as follows. Sulfate and chloride seemed to be aetiological agents to make inflammation - which sometimes develops into ulcer, polypus and cancer - in stomach mucous membrane. On the contrary calcium has antiphlogistic effect, because of its capillary permeability reducing action, which may also prevent lodging of tumour cells in haematogenous metastasis of cancer in microcirculation system. The sunshine duration may be concerned with calcium absorption through its action of vitamin D production on skin.
