The influence of the degree of caloric restriction on the formation of skin tumors and hepatomas in mice.

Summary 1.Chronic caloric restriction inhibits the formation of the spontaneous hepatoma of the C3H male mouse. This caloric effect is in accord with that obtained with all previously studied tumors. 2.In an experiment in which graded caloric intakes were given to several groups of mice, it was demonstrated that with decreasing caloric intake there was a decreasing incidence of both methylcholanthrene-induced skin tumors and spontaneous hepatomas. 3.The relationship between caloric intake and incidence of these two types of tumors may be mathematically stated: the probit of the incidence of tumors is a straight line function of the logarithm of the daily caloric intake. This implies, and the data agree, that the largest inhibition of tumor formation, for proportionate reduction in food intake, occurs near the level of 50 per cent incidence of tumors.