Harold P. Morris

EFFECTS ON THE GENESIS AND GROWTH OF TUMORS ASSOCIATED WITH VITAMIN INTAKE

Nutritional factors, such as vitamins, which may be involved in the genesis of cancer should be clearly distinguished from nutritional constituents which influence the growth of a tumor that is already present, because the two processes may be quite different. Likewise, it is not possible to make extensive generalizations from the effects obtained on one tumor to those which may prevail for other types of tumors. I t is exceedingly difficult as well as hazardous, therefore, at the present time, fully to evaluate the role of vitamins in the origin and growth of cancer. I t is, nevertheless, reasonable to believe that certain essential dietary constituents, including vitamins, are involved in the genesis or growth of tumors. The experiments described in this paper were conceived and carried out to show the effects of different vitamin levels on the genesis as well as the development of tumors. In the change to malignancy, the requirements of the altered cell may bc such that it now requires more, less, or none of some vitamin essential to the normal cell. Two objectives of these nutrition studies have thus been the determination of the influence of vitamin intake (1) on the in viuo growth of tumors already formed, and ( 2 ) on the genesis of cancer. The availability in pure form of pantothenic acid, pyridoxine, thiamine, and riboflavin made feasible the initiation of such experiments. The problem so far has included investigations of the following points: (1) the quantitative appraisal of the host’s requirement for the given vitamin; ( 2 ) effect of a rapidly produced, extreme deficiency of the vitamins on the growth of tumors; (3 ) effect on the growth of the tumor of a vitamin intake just adequate to maintain body weight of the nontumor-bearing adult animal; (4) other effects of vitamin deficiency or supplementation on tumor and host; and (5) influence of a prolonged partial vitamin depletion of the animal on the genesis of spontaneous mammary tumors. Not all of the above points will be fully presented in this discussion, and many details already published or to be published will be omitted in order to give briefly an overall picture of the in vivo studies so far completed.

Thyroxine depression of mouse thyroid iodide trap activity.

Summary Chronic treatment with thyroxine was no more effective than hypophysectomy in depressing the thyroid iodide trap. TSH had some stimulating effect on the activity of the thyroid iodide trap. The combination of TSH and PTU caused a greater response, but insufficient to serve as an assay technic for thyrotropin.