Phenotypic subtypes as a novel validated prognostic classification system for patients with colorectal cancer.

625Background: There has been enormous effort to develop a prognostic genomic classification of colorectal cancer (CRC). As a result, mismatch repair (MMR) status was established as a prognostic marker in addition to TNM-staging. Phenotypic subtypes were recently proposed that stratified patient survival, however their clinical utility had not been compared to other proposed classification systems including consensus molecular subtypes (CMS) or current prognostic markers including MMR status. Methods: Three patient cohorts, a pilot cohort of 237 stage I-III CRC patients, a validation cohort of 879 stage I-III CRC patients, and the AMC-AJCCII-90 cohort with 81 stage II colon cancer patients were utilised to investigate associations between phenotypic subtypes, MMR status, CMS and patient survival. Results: In the pilot cohort, phenotypic subtype stratified cancer-specific survival (P < 0.001). In the validation cohort, phenotypic subtype stratified overall (p = 0.003) and cancer-specific survival (CSS, p <...