Shifting Demographics: A Temporal Analysis of the Alarming Rise in Rectal Adenocarcinoma Among Young Adults

Background

Rectal adenocarcinoma has long been associated with older adults, with routine screening typically beginning at age 45 or older. However, recent data reveal a concerning rise in rectal cancer incidence among adults under 40. These early-onset cases often present at later stages and may have distinct biological features. While some research attributes this trend to genetic or environmental factors, the contribution of socioeconomic disparities and healthcare access has not been fully explored. Identifying these influences is essential to shaping targeted prevention and early detection strategies for younger populations.

Objective

To evaluate temporal trends in rectal adenocarcinoma among young adults and assess demographic and socioeconomic predictors of early-onset diagnosis.

Methods

Data were drawn from the National Cancer Database (NCDB) for patients diagnosed with rectal adenocarcinoma from 2004 to 2022. Among 440,316 cases, 17,842 (4.1%) occurred in individuals under 40. Linear regression assessed temporal trends, while logistic regression evaluated associations between early-onset diagnosis and variables including sex, race, insurance status, income level, Charlson-Deyo comorbidity score, and tumor stage. Statistical significance was defined as α = 0.05.

Results

The number of young adults diagnosed rose from 424 in 2004 to 937 in 2022—an increase of over 120%. Each year was associated with a 1.7% rise in odds of early diagnosis (OR = 1.017, p < 0.001). Male patients had 24.7% higher odds (OR = 1.247, p < 0.001), and Black patients had 59.3% higher odds compared to White patients (OR = 1.593, p < 0.001). Non-private insurance was linked to a 41.6% decrease in early diagnosis (OR = 0.584, p < 0.001). Income level was not significant (p = 0.426). Lower Charlson-Deyo scores and higher tumor stages were also associated with early-onset cases.

Conclusions

Rectal adenocarcinoma is increasingly affecting younger adults, with significant associations across demographic and insurance variables. These findings call for improved awareness, early diagnostic strategies, and further research into underlying causes to mitigate this growing public health concern.