SPP1 and neoplasm: While we observed no difference in circulating osteopontin levels between patients with moderately (G2) or poorly (G3) differentiated tumours (Supplementary Figure S1a), left- or right-sided primary CRC (Supplementary Figure S1b), KRAS mutated and wildtype CRC patients (Supplementary Figure S1c), patients with normal or impaired ECOG performance status (PS) (Supplementary Figure S1d) as well as male and female patients (Supplementary Figure S1e), initial osteopontin serum levels were significantly elevated in patients with a high FONG score [10] (Supplementary Figure S1f).