The Impact of Age in the Treatment of Patients with Localized Rectal Cancer - Survival Outcomes from the National Cancer Database

Abstract Background Multimodal therapy for localized rectal cancer (RC), including (neo-)adjuvant systemic therapy and surgery, has improved survival outcomes significantly. However, these results cannot be extrapolated to elderly patients. Aims The aim of this study was to evaluate whether patients aged >/=75 years receive substandard oncological treatment compared to their younger counterparts and if this affects survival. Methods This is a retrospective study from the National Cancer Data Base (NCDB) for histologically confirmed localized RC from 2002–2014. Non-comorbid patients (i.e., Charlson-Deyo comorbidity index 0) between >/=50 - </=85 years were included and assigned to a younger (<75 years) and an older (>/=75 years) group.Treatment modalities and their impact on relative survival (RS) were analyzed using loess regression models. Mediation analysis was performed to measure the independent relative effect of age on RS. Results 59,769 patients were identified of which 48,389 (81.0%) were assigned to the younger group (<75 years). Oncologic resection was performed in 79.6% of the younger compared to 67.2% of the older patients (p<0.001). Chemo- (74.3% vs. 56.1%) and radiotherapy (72.0% vs. 58.1%) were provided more often to younger patients (p<0.001). Increasing age was associated with higher 90-day (2.0% vs. 1.1%) mortality in the elderly group (p<0.001) and worse RS rates (multivariable adjusted HR: 1.93 (95%CI:1.87-2.00), p<0.001). Guideline adherent oncological therapy resulted in a significant increase of 5-year RS in both groups (multivariable adjusted HR: 0.80 (95%CI:0.74-0.86), p<0.001). Mediation analysis revealed that RS was mainly affected by age itself (84%) rather than the choice of therapy. Conclusions The likelihood to receive substandard oncological therapy increases in the older population and negatively affects RS. Since age itself has a major impact on RS, it is important to identify patients potentially eligible for standard oncological care regardless of their age to improve survival outcomes for this age group.