Fibroblast activation protein identifies Consensus Molecular Subtype 4 in colorectal cancer and allows its detection by Ga-FAPI-PET imaging.

Background: In colorectal cancer (CRC), the consensus molecular subtype 4 (CMS4) is associated with therapy resistance and poor prognosis. Clinical diagnosis of CMS4 is hampered by locoregional and temporal variables influencing CMS classification. Diagnostic tools that comprehensively detect CMS4 are therefore urgently needed.