Survival benefit from evidence-based treatment for rectal cancer among older people – Analysis of SEER-medicare

Introduction The treatment of stage III rectal cancer (RC) is complex and requires a multidisciplinary approach. Evidence-based guidelines (EBG) exist for the treatment of RC. We aimed to determine adherence to EBG in the treatment of stage III RC and the impact on survival in older adults. Materials and methods This is a retrospective study of patients within the Surveillance, Epidemiology, and End Results program (SEER). We included adults with stage III RC between 2007 and 2018 with one pathologically confirmed primary tumor. We defined guideline-based care as receipt of: chemoradiation within 6 months of date of diagnosis; surgery within 6 months of completion of chemoradiation; and chemotherapy after surgery. Overall survival (OS) and cancer-specific survival (CSS) were analyzed using the Kaplan-Meier method. Multivariable Cox regression was performed to determine factors associated with survival. Results We identified 3962 patients, and 1945 (49.1%) were female. There were 1707 (43.1%) with a Charlson Comorbidity Index of zero. Of the total, 994 (25.1%) received all guideline-based treatments. Factors associated with lack of guideline-based care included age, comorbidities, income, and geographic location. Guideline-based care was associated with increased OS (HR: 0.55, 95% CI: 0.49–0.60) and CSS (HR: 0.59, 95% CI: 0.48–0.73). Discussion Although 43.1% of the cohort had a comorbidity index of zero, only 25.1% received all guideline-based treatments. Deviation from guideline-based care had a significant impact on OS. Our data show that more efforts can be made to recommend multimodal RC treatment among older adults.