Comparison of the disease presentation of early- vs. later-onset colorectal cancer within the prospective ColoCare study.
Authors: Gottschalk Zachary , Redman Mary Weber , Baker Kelsey K. , Ulrich Cornelia M , Siegel Erin M. , Figueiredo Jane C. , Shibata David , Toriola Adetunji T. , Gigic Biljana , Ose Jennifer , Lin Tengda , Hardikar Sheetal , Li Christopher I. , Cohen Stacey A. 
Published: January 2024

91 Background: Within the United States (US), colorectal cancer (CRC) is the third most diagnosed cancer and the second leading cause of cancer-related fatalities, with a median age at diagnosis of 66 years. While the incidence of sporadic CRC is decreasing, the incidence in those aged 18-49 years has steadily increased. Younger patients are not often screened for CRC, and they are often diagnosed at a later stage of disease. Herein, we compare the presenting symptoms and stage at diagnosis of early-onset CRC to disease in those aged 50 or greater. Methods: The ColoCare Study is a prospective cohort enrolling individuals diagnosed with primary CRC across six cancer centers in the US and one site in Germany. Serial questionnaires administered at baseline assessed demographic characteristics and symptoms experienced prior to diagnosis, while clinical data such as staging and pathology were abstracted from medical records. For this analysis, only patients who had available age and tumor stage were included. Patients diagnosed <50 years old were categorized as “early-onset” and ≥50 as “later-onset.” Fisher’s exact test was used to compare demographics, disease state characteristics, and symptoms experienced by age group. Statistical significance was based on a two-sided alpha level of 0.05. Results: 1,996 patients were included in this analysis. Of these, 1,508 (76%) were later-onset (mean diagnosis age 64, range: 50-94), while 488 (24%) were early-onset (mean age: 42, range: 21-49). Demographic data was similar between early- and later-onset patients in terms of gender and primary site. Disease stage at diagnosis was significantly associated with age (p < 0.001). A higher proportion of early-onset patients had advanced disease at the time of diagnosis compared to later-onset for both stage III (43% vs 37%) and stage IV disease (28% vs 17%). For patients with available histologic data, younger patients were more likely to have vascular (35% vs 28%, p=0.03) and perineural invasion (33% vs 21%, p <0.001) at diagnosis. Early-onset patients were also more likely to report symptoms prior to diagnosis (95% vs 83%, p <0.001). Specifically, younger patients reported higher rates of abdominal pain (46% vs 23%, p < 0.001), blood in stool (71% vs 54%, p <0.001), and changes in bowel habits (54% vs 40%, p <0.001). General weakness and vomiting were also statistically more likely to be noted at presentation in early-onset patients. Conclusions: In this prospective real-world cohort analysis, patients with early-onset CRC are more likely to be diagnosed with more advanced disease at presentation than later-onset patients. This analysis highlights key symptoms that should raise awareness as possible indicators of a new diagnosis of CRC, even in individuals <50 years old. Additional disease comparisons between age groups will be presented at the meeting.