Pediatric and Adolescent Rectal Adenocarcinoma: A National Cancer Database Analysis and Comparison to Adults.

[INTRODUCTION] Rectal adenocarcinoma is exceptionally rare in children and is now recognized as a distinct entity from colon cancer, thereby requiring different treatment approaches. Differences between the pediatric and adult populations have not been previously explored. This study aims to characterize tumor biology, disease presentation, treatment, and survival outcomes in pediatric and adolescent rectal cancer with the goal of improving care in this population.

[METHODS] A retrospective analysis was conducted using the National Cancer Database (NCDB) for patients aged 0-90 years old diagnosed with rectal adenocarcinoma between 2004 and 2019. Patients were stratified into three age cohorts: pediatric and adolescents (PEDS) (≤21 years old), young adults (YAs) (22-49 years old), and older adults (OAs) (≥50 years old). Chi-squared, multivariate regression, Kaplan-Meier analysis, and Cox regression were performed.

[RESULTS] A total of 181,246 patients (127 PEDS, 34,552 YAs, and 146,567 OAs) were included. A greater proportion of PEDS presented with poorly differentiated or undifferentiated tumors. PEDS more commonly presented with Stage III or IV disease. PEDS had equivocal overall survival (OS) compared to OA in all stages and YA in Stage IV disease. PEDS had worse OS compared to YA in Stage I (hazard ratio [HR]: 3.33, confidence interval [CI]: 1.49-7.42, p = 0.003), Stage II (HR: 3.01, CI: 1.62-5.60, p < 0.001), and Stage III (HR: 2.41, CI: 1.69-3.44, p < 0.001) disease.

[CONCLUSION] PEDS with rectal adenocarcinoma present with more aggressive, advanced disease and often worse survival compared to younger adults. The findings suggest distinct biological behavior of pediatric and adolescent rectal cancer, emphasizing the need for further research in this population.