Inhibition of solid tumors by nitrosoureas. 1. Lewis lung carcinoma.

The utility of the Lewis lung carcinoma as a secondary screen for the evaluation of nitrosoureas as anticancer agents has been assessed. The activity of this series of compounds was determined against both the early (before metastasis) and late (after metastasis) forms of the disease. Although some exceptions were noted, compounds most active against the early form of the disease were most active against the established tumor. A differentiation in activity based on the Lewis lung system was evident with nitrosoureas equally active against leukemia L1210, although the significance of this differentiation with respect to the human disease has not yet been established.