Nutritional factors in the design of more selective antitumor agents.

Manipulation of nutritional factors, either by supple mentation or by creation of a deficiency, has already been found to be effective in the therapy of a few specific neoplasms. Particular examples are the Walker 256 carcinoma, which is sensitive to folate deficiency but not to Methotrexate administration; certain lymphoblastic leukemias which are relatively sensitive to asparagine deficiency; and some lymphomas which are sensitive to riboflavin deficiency. However, the area is as yet relatively unexplored, due partly to the difficulties in obtaining nutritional depletion and due more to lack of knowledge of those specific nutritional requirements by which specific tumors might differ from the requirements of their host.