Age and primary cancer site did not show an influence on OS, whereas STC1 plasma levels (HR = 1.35, 95% CI, 1.08–1.68; P = 0.009), treatment with regorafenib (HR = 0.71, 95% CI, 0.58–0.86; P < 0.001), ECOG performance status (HR = 1.53, 95% CI, 1.27–1.84; P < 0.001), and the presence of liver metastases (HR = 1.56, 95% CI, 1.21–2.02; P < 0.001) suggested an effect on OS (cross-validated C-index = 0.701). Here, STC1 is linked to cancer.