Abstract PR005: Outcomes in colitis-associated metastatic colorectal cancer and intersection with early-onset and signet ring cell carcinoma

Patients with inflammatory bowel disease (IBD) have a higher risk of developing colorectal cancer (CRC) and mortality from colitis-associated CRC (CA-CRC) is currently rising. Clinical and molecular differences between CA-CRC and sporadic-CRC (S-CRC) have been previously identified, however there are conflicting reports on outcomes of CA-CRC, especially for those with metastatic CRC (mCRC). Due to the earlier onset of CA-CRC, undiagnosed IBD has been speculated to be a contributing factor to the rising prevalence of early-onset CRC (EOCRC), but confirmatory studies are lacking. In this retrospective study, three independent CRC patient datasets from MDACC were used – the mATTACC discover cohort (n=32 CA-mCRC; n=425 S-mCRC), a tumor registry (n=1696, excluding MSI-High samples), and a real-world evidence (RWE) validation dataset (n=269 CA-mCRC; n=29,596 S-mCRC). These cohorts were analyzed in order to explore characteristics of patients with CA-mCRC, evaluate the amount of EOCRC attributable to CA-mCRC, and compare outcomes of patient populations with CA-mCRC. Median age at diagnosis for patients with CA-mCRC (48yo) was significantly lower compared to S-mCRC (58yo; p