A single institution review of early onset colorectal cancer: 10 year retrospective clinical study.

e15675 Background: The incidence of early onset (EO) colorectal cancer is on the rise in the western world, with approximately 10% of all new cases diagnosed at or before the age of 50. We sought to characterize EO vs average onset (AO) colorectal cancer patients at a dedicated cancer center over a ten-year period. Methods: A retrospective review was performed of an institutional database that prospectively collects clinical and demographic data of all patients with colon or rectal (including rectosigmoid) cancers. Patients were then categorized by age range and their clinical characteristics recorded. Results: A total of 5,890 patients with colorectal cancer were identified between the years 2014 and 2023, with 1,316 (22.3%) diagnosed at or before age 50. Overall, median follow up duration was 1082.5 days (IQR 588-1916). Within the EO group, 800 (60.8%) had colon cancer and 516 (39.2%) had rectal cancer. Yearly rates of colorectal cancer in both EO and overall cancer groups, as well as the ratio of EO cases, remained stable within the study period. EO colorectal cancer was associated with lower overall mortality rate (37.5% vs 41.6%, p = 0.009), as well as lower histologic grade at diagnosis with fewer poorly differentiated (9.2% vs 11.1%) and undifferentiated tumors (2.1% vs 3.4%) when compared to AO group (p = 0.002). There were no differences in the rate of local (0.3% vs 0.5%), regional (0.5% vs 0.8%) or distant recurrences (5.6% vs 4.9%) in the EO and AO groups (p = 0.56). In the subset analysis between colon and rectal cancers, colon cancer was more common within the AO group as compared to EO group (64.3% vs.60.8%, p = 0.02). While there were no differences seen in overall mortality between the groups for colon cancer, rectal cancer had higher overall mortality in the AO group (39.7% vs 30.6%, p = 0.0002). Conclusions: EO colorectal cancer at or before the age 50 may confer lower mortality rate as well as lower histologic grade when compared to AO colorectal cancer patients. In the AO population as compared to the EO group, colon cancer appears to be more prevalent albeit with higher overall mortality rate for rectal cancers. We did not find any yearly difference in proportion of EO patients. Characteristics and outcomes of early onset versus average onset colorectal cancer. EO CRC (n=1,316) AO CRC (n=4,574) P-value Gender (n, %) 0.37 Male 691 (52.5) 2495 (54.5) Female 625 (47.5) 2079 (45.5) Primary sites (n, %) 0.02 Colon 800 (60.8) 2670 (64.3) Rectum 516 (39.2) 1904 (35.7) Grade (n, %) 0.002 Well differentiated 38 (8.0) 85 (3.8) Moderately differentiated 291 (61.1) 995 (56.7) Poorly differentiated 44 (9.2) 293 (11.6) Undifferentiated 10 (2.1) 65 (3.7) Recurrences (n, %) 0.56 Local 4 (0.3) 23 (0.5) Regional 6 (0.5) 37 (0.8) Distant 73 (5.6) 226 (4.9) Overall mortality (n, %) 494 (37.5) 1904 (41.6) 0.009 EO: early onset,