Patterns of Sociodemographic and Clinicopathologic Characteristics of Stages II and III Colorectal Cancer Patients by Age: Examining Potential Mechanisms of Young-Onset Disease.

Background and Aims. As a first step toward understanding the increasing incidence of colorectal cancer (CRC) in younger (age < 50) populations, we examined demographic, clinicopathologic, and socioeconomic characteristics and treatment receipt in a population-based sample of patients newly diagnosed with stages II and III CRC. Methods. Patients were sampled from the National Cancer Institute's Patterns of Care studies in 1990/91, 1995, 2000, 2005, and 2010 (n = 6, 862). Tumor characteristics and treatment data were obtained through medical record review and physician verification. We compared sociodemographic and clinicopathologic characteristics and treatment patterns of younger (age < 50) and older (age 50-69, age ≥ 70) CRC patients. Results. Younger patients were more likely to be black (13%) and Hispanic (15%) than patients aged 50-69 years (11% and 10%, resp.) and ≥70 years (7% each). A larger proportion of young white (41%) and Hispanic (33%) patients had rectal tumors, whereas tumors in the right colon were the most common in young black patients (39%). The majority of younger patients received chemotherapy and radiation therapy, although receipt of microsatellite instability testing was suboptimal (27%). Conclusion. Characteristics of patients diagnosed with young-onset CRC differ considerably by race/ethnicity, with a higher proportion of black and Hispanic patients diagnosed at the age of < 50 years.