Lack of efficacy of water-suppressed proton nuclear magnetic resonance spectroscopy of plasma for the detection of malignant tumors
Magnetic Resonance Spectroscopy
Water-suppressed proton nuclear magnetic resonance (NMR) spectroscopy of plasma has been proposed by Fossel et al. (N Engl J Med 1986; 315:1369-76) as a technique for detecting malignant tumors. In their analysis, plasma samples from patients with cancer were clearly distinguished from those of normal subjects by measuring and averaging the methyl and methylene line widths of plasma lipoproteins in NMR spectrums. To evaluate this diagnostic procedure further, we collected and analyzed by NMR spectroscopy 145 samples of plasma from patients who served as controls, most of whom were undergoing orthopedic or cardiac surgery (n = 66); patients with a variety of untreated malignant tumors (n = 25) or treated malignant tumors (n = 18); and patients with hyperplastic or "premalignant" diseases, such as benign prostatic hyperplasia and ulcerative colitis (n = 36). All the samples were coded, and NMR spectroscopy was performed without knowledge of the patients' clinical status. There were no significant differences in the NMR line widths among the four study groups (P greater than 0.05 for all pairwise comparisons). The specificity and sensitivity of this method for distinguishing the control patients (mean line width [+/- SD], 44.0 +/- 7.4 Hz) from those with untreated cancer (43.8 +/- 6.9 Hz) were poor, with a false positive rate of 52 percent (34 of 66) and a false negative rate of 56 percent (14 of 25). Inverse correlations of line widths with age (P less than 0.01) and with the plasma triglyceride level (P less than 0.001) were detected. We conclude that NMR spectroscopy of plasma is not an accurate test for the detection of malignant tumors.