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

A sensitive and specific blood test for cancer has long been sought. The water-suppressed proton nuclear magnetic resonance (NMR) spectrum of plasma is dominated by the resonances of plasma lipoprotein lipids. We measured the mean line widths of the methyl and methylene resonances, which were found to be correlated with the presence or absence of malignant tumors. Values for the average line width were lower in patients with cancer. We analyzed plasma from 331 people (normal controls, patients with malignant and benign tumors, patients without tumors, and pregnant patients); NMR analysis and measurement of line widths were blinded to diagnosis or patient group. The mean line width for 44 normal controls (+/- SD) was 39.5 +/- 1.6 Hz. For 81 patients with untreated cancer, demonstrated by biopsy, the line width was 29.9 +/- 2.5 Hz. Patients with malignant tumors were reliably distinguished from normal controls by this method (P less than 0.0001), and differed from patients with diseases that did not involve tumors (line width, 36.1 +/- 2.6 Hz; P less than 0.0001). Patients with benign tumors (e.g., those of the breast, ovary, uterus, and colon) had line widths of 36.7 +/- 2.0 Hz and were different from those with malignant tumors (P less than 0.0001). However, pregnant patients and those with benign prostatic hyperplasia had line widths consistent with the presence of malignant tumors. The narrowing of lipoprotein-lipid resonances with cancer is consistent with the response of a host to tumor growth. We conclude that these preliminary results demonstrate that water-suppressed proton NMR spectroscopy is a potentially valuable approach to the detection of cancer and the monitoring of therapy.