Rising colorectal cancer death rates among young adults are largely concentrated among those with lower educational attainment, according to a nationwide cross-sectional analysis published in JAMA Oncology. As a result, Jemal et al reported that the disparity in mortality between individuals with up to 12 vs at least 16 years of education nearly doubled over the past 3 decades.
The investigators added that their findings “suggest a role of social determinants of health for the increasing burden of this disease.”
Study Details
This study analyzed nationwide colorectal cancer mortality among individuals aged 25 to 49 years from 1994 to 2023. Mortality data stratified by 5-year age groups, sex, and educational attainment (≤ 12, 13–15, and ≥ 16 years of education) were obtained from the National Center for Health Statistics (NCHS). Population estimates for the corresponding categories were obtained from the NCHS and the U.S. Census Bureau.
Temporal annual mortality trends (age-standardized to the 2000 U.S. population) were analyzed separately by sex and educational level using Joinpoint regression software from the National Cancer Institute. In addition, mortality rate ratios (RRs) and rate differences (RDs) comparing individuals with up to 12 vs at least 16 years of education by sex were calculated for 1994 and 2023.
Mortality by Education
Between 1994 and 2023, 101,037 individuals aged 25 to 49 years (mean age = 43.0 years) died from colorectal cancer, including 56,007 men (55.4%) and 45,030 women (44.6%).
Death rates among men with up to 12 years of education increased over the study period, rising from 0.6% per year (95% confidence interval [CI] = 0.1%–0.8%) between 1994 and 2017 to 2.8% per year (95% CI = 1.3%–7.5%) between 2017 and 2023. In contrast, among men with at least 16 years of education, rates rose by 1.4% per year (95% CI = 0.7%–2.6%) from 2005 to 2023, following an earlier decrease of 2.2% per year (95% CI = −5.7% to −0.7%) from 1994 to 2005. A statistically significant increase was observed among women with 15 or fewer years of education.
Between 1994 and 2023, widening educational disparities were observed, with RRs comparing 12 or fewer vs 16 or more years of education increasing among men from 1.50 (95% CI = 1.32–1.69; RD = 1.5 [95% CI = 1.1–1.9] deaths per 100,000) to 1.93 (95% CI = 1.74–2.14; RD = 2.8 [95% CI = 2.4–3.2]) and among women from 1.55 (95% CI = 1.35–1.79; RD = 1.3 [95% CI = 0.9–1.7]) to 1.81 (95% CI = 1.62–2.04; RD = 2.0 [95% CI = 1.6–2.4]).
Clinical Considerations
Limitations of this study include reliance on self-reported or next-of-kin–reported educational attainment and the inability to further stratify by other social determinants of health, such as race and ethnicity and insurance status, because of limited data availability. Furthermore, the investigators wrote that the results should be interpreted with caution given compositional changes in educational strata over time and the potential influence of the COVID-19 pandemic, although its impact on cancer-related mortality appears to have been minimal.
Reflecting on their findings, the investigators commented, “Reasons for the increasing burden of young-onset colorectal cancer are poorly understood. Suspected risk factors include increases in the prevalence of obesity, physical inactivity, and unhealthy diet during childhood and young adulthood, which are known to be elevated among children and young adults with lower socioeconomic status. The widening disparity may also in part reflect socioeconomic inequality in receipt of colorectal cancer care.”
Ahmedin Jemal, DVM, PhD, of the American Cancer Society, is the corresponding author of the article in JAMA Oncology.
Disclosure: The study was funded by the Intramural Research Department of the American Cancer Society. The study authors reported no conflicts of interest.
