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 older patients with CA.
Methods: A total of 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) cancer 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 tumor size was 47 mm with a mean number of positive lymph nodes of 1.1. Most tumors 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 tumor 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 older patients with CA is associated with advanced age, advanced stage/grade, left colon site, larger tumor, lower income and not receiving surgery or chemotherapy. Future research is needed to individualize and tailor therapy and approaches in this age group and to study similar group in the UK for comparison with this US data. Limitations include data/variables inaccuracy and missingness in SEER especially treatment variables, the lack of quality of life, performance status data, and comorbidities, and not doing subgroup analyses for different age groups.