A, Mean NMR spectra for samples from unwell patients with either confirmed solid tumor diagnoses (red, n = 17) or confirmed noncancer diagnoses (black, n = 175). B, Difference spectrum showing regions that were increased in patients with solid tumors (red), decreased in patients with solid tumors (blue), or unchanged (gray). C, Insets showing magnified regions at points of significant difference between unwell with solid tumor spectra (red) and unwell without cancer spectra (black). NAC, N-acetylated glycoproteins.