31P NMR spectra of extremity sarcomas: diversity of metabolic profiles and changes in response to chemotherapy.

We have used 31P NMR spectroscopy to study 22 patients with suspected sarcomas prior to any treatment. The spectra are characterized by the same peaks noted in murine tumors. The mean pH was 7.14 +/- 0.08 and PCr/Pi was 1.18 +/- 0.83. Comparison of pH and PCr/Pi ratios in human and a murine tumor with a low hypoxic cell fraction revealed no significant differences. Six patients subsequently received chemotherapy and three responded to therapy (based on pathologic examination and/or tumor reduction greater than 50%). The three responding patients were noted to have significantly lower PDE/PME in their pretreatment spectra than the three nonresponding patients. The three responding patients with sarcomas also showed a rise of greater than 100% in PDE/PME during the first cycle of therapy. Two of the responding patients had an increase of 0.37 pH units during this interval, which was not detected in the nonresponding patients. These data suggest that 31P NMR spectroscopy may be a useful prognostic indicator in conjunction with other clinical parameters.