Detection of malignant tumors: water-suppressed proton nuclear magnetic resonance spectroscopy of plasma.

Average linewidths of methyl and methylene proton resonances of plasma lipoproteins from healthy controls and untreated cancer patients were measured in water-suppressed proton spectra obtained at 400 MHz. In contrast to a previous report (E. T. Fossel, J. M. Carr, and J. McDonagh, N. Engl. J. Med. 315, 1369 (1986] no statistically significant difference (P greater than 0.5) was found between the average linewidths in plasma samples from 20 normal controls (36.0 +/- 6.4 Hz) and 17 untreated cancer patients (34.6 +/- 6.3 Hz). When the effect of lactate was removed by graphical extrapolation, a small but marginally significant (P = 0.08) difference was observed between the average linewidths of the normal controls (35.1 +/- 5.8 Hz) and untreated cancer patients (31.8 +/- 5.2 Hz). However, there was still a large overlap between the two groups. In addition, substantial day to day variations in the linewidths of samples from the same individuals were observed. We conclude that these measurements cannot be used to detect cancer.