The effect of N-methylformamide on radiocurability of murine tumors.

N-Methylformamide (NMF) is a polar solvent with maturational activity, i.e., it induces malignant cells to form more differentiated phenotypes. In addition, it renders tumor cells more sensitive to chemotherapeutic drugs and ionizing radiation. In the present study, NMF failed to augment radiocurability, as measured by the single-dose TCD50 assay, of two murine tumors: an 8-mm fibrosarcoma (FSA) and a 6-mm mammary carcinoma (MCA-K). NMF, at a dose of 300 mg/kg, was given ip daily for several days before and/or after local tumor irradiation.