Two other elements of the cellular compartment have appeared interesting. Manganese by intervening as a catalyst in processes resulting in an activation of oxygen, indirectly manifests D inducing character. Its presence in smaller amounts in tumors or cancerous organs than in controls, has been considered. Just as with copper, no effects are seen in treating tumors with manganese compounds although a certain degree of preventive action is obtained in tumors induced by carcinogens. Similarly, with cobalt we have obtained a certain degree of prevention against tumor induction by carcinogens but no effect upon the evolution of tumors once they have appeared. No effects have been seen in transplanted tumors.

Heavier Elements

We have studied the activity of elements corresponding to the lower levels—such as strontium and tin for the nuclear; barium, gold and lead for the sub morphologic; and cesium for the primary biological compartments. The lower the level of the element, the greater appears to be the preventive effect against induction of tumors by carcinogens. But the minimal, or complete absence of effect upon already existing tumor cells remains unchanged.

As mentioned above, we connected this paradoxical activity to the fact that, while normal cells are able to manufacture compounds through which the appearance of a cancerous entity can be prevented, these compounds are no longer formed if an entity is already cancerous.

These have been the considerations forming the basis for an entire series of studies of the role of various elements in the pathogenesis of cancer.

Elements In The Pathogenesis Of Cancer

Investigations have been made of the amount and form of the element present in the normal animal as compared to the cancerous animal. The quantitative and especially qualitative differences have been seen to indicate the site of the abnormality largely responsible for the lack of influence exerted by the element. The results explain why the administration of the element alone is unable to influence the evolution of an already existing cancerous process. More interesting, they show what compound of the element could have an influence. This research, which is in progress, opens the door for possible therapeutic applications. It is through such compounds, present in the normal and lacking in the cancer stricken animal, that attempts are being made to influence the evolution of cancer. An important step has been the finding that suitable compounds can be obtained by the treatment of fresh organs in vitro with some of the elements. Their study may make possible synthetic preparation of suitable compounds. The few results already obtained in experiments with animals confirm that D inducing activity represents a factor which the promising elements share.