Recent work suggests that significant differences might exist in the microwave absorption spectra of normal and malignant cells. In addition, there is other evidence that millimeter wave radiation might be used in cancer therapy. The proposed studies will provide a detailed evaluaton of the absorption spectra in the 8-90 GHz range of: (a) B16 murine melanoma and transformed BHK21/C13 cells grown both in vivo and in vitro; (b) two lines of normal and transformed cells bearing temperature-sensitive viruses; (c) three different systems in which normal cells can be compared with: virus transformed cells, isolated spontaneous transformants, and drug-induced transformants; (d) phenotypically transformed cells. Evaluation of the quantitative results obtained from these experiments will show whether diagnostic microwave spectroscopy can be used as a tool in cancer screening. Experiments will also be conducted to determine whether significant differences in sensitivity to microwave irradiation exist between normal and transformed cells. These experiments will include a study of the effects of microwave irradiation on: (a) cell growth in vivo and in vitro; (b) morphology of several cloned cell lines and primary cell cultures using both light and electron microscopy; (c) selected biochemical parameters; (d) animals bearing B16 murine melanoma or BHK21/C13 solid tumors. These studies will indicate the extent to which millimeter wave radiation can be used as a possible form of cancer therapy.