67 Background: Colon cancer remains one of the leading causes of cancer death worldwide. There has been a renewing interest in the role of PTL (right- or RS vs. left-sided or LS) in CC for their differences in biology, prognostic and predictive features. Given the increasing incidence of early-onset (age 20-49) CC, coupled with their longer life expectancy, we seek to examine the effects of PTL and age in the development of SPM in a population-based cohort. Methods: Surveillance, Epidemiology, and End Results (SEER) Program data were queried to identify CC PTS diagnosed between 1973-2015 with complete follow-up information and available data on SPM. Using SEER*Stat, we calculated standardized incidence ratios (SIRs) -- the ratio of observed to expected cases of SPM based on incidence data in the general US population and compared by PTL (RS vs. LS) and age of diagnosis (20-49 vs. >49). Results: A total of 269,442 (RS/LS=46.4%/53.6%) CC PTS were obtained. Overall RS, compared with LS, CC PTS have a higher likelihood of developing SPM in all sites (OR: 1.09, 95% CI: 1.08- 1.11 vs. 1.03, 1.02-1.04). RS CC PTS and age 20-49 group, compared with other subgroups, has a much greater likelihood of being diagnosed with the following SPM:small intestine, urinary tract, bile duct, gynecologic (GYN), and stomach cancers, as shown in the Table below. Conclusions: Our results show that the increased risk in non-colonic SPMs in CC PTS is associated with RS CC and age less than 49, suggesting the implications on survivorship care and surveillance of SPMs. Furthermore, there may be a possible overlap with Lynch syndrome in these PTS with SPM given the overlap in the presentation of cancer patterns and early-onset of CC, suggesting the indication for MMR testing. [Table: see text]
Racial/ethnic disparities in early‐onset colorectal cancer: implications for a racial/ethnic‐specific screening strategy