3195 Determinants of survival of elderly patients with colorectal adenocarcinoma: a population-based analysis of 191,417 patients

Abstract Introduction Colorectal adenocarcinoma (CA) is the second most common cause of cancer mortality in the United States (US) and the United Kingdom (UK). The median age of diagnosis is 70–72 years old. This study aims to explore the factors associated with survival in elderly patients with CA. Methods 191,417 patients with CA diagnosed between 2011 and 2021 who are aged 65 years or older were extracted from the US Surveillance, Epidemiology, and End Results (SEER) Database. Univariable and Multivariable Cox regression was performed to explore the factors associated with survival in this group of patients. Kaplan Meier plots for overall survival (OS) were generated. Results Most patients were aged 65–75 (45.9%) were males (50.8%) and of white race (70.5%). The most common household income category was 55,000–75,000 USD (34.2%). Mean tumour size was 47 mm with a mean number of positive lymph nodes of 1.1. Most tumours were right sided (40.6%). The commonest stage was stage 2 (25.1%) and the commonest grade was grade 1 (63.3%). The most common metastasis organ was the liver (87.6%). 74.1% had surgical resection, 30.9% had chemotherapy and 10.4% had radiotherapy. Five-year OS was 46.8%. Multivariable cox regression showed that survival is worse with advanced age, larger tumour size, worse grade, left colon, male sex, lower income, not receiving chemotherapy, not undergoing surgical resection, advanced stage and having metastases. Conclusion Poor survival in elderly patients with CA is associated with advanced age, advanced stage/grade, left colon site, larger tumour lower income and not receiving surgical or chemotherapy. Future research is needed to individualise and tailor therapy and approach in this age group. Limitations include data inaccuracy and missingness in SEER especially treatment variables and the lack of quality of life and performance status data.