Abstract
BACKGROUND: Many patients surviving from colorectal cancer die of causes irrelevant to cancer. This study was designed to describe the leading causes of death among older patients diagnosed with colorectal cancer and assess factors that are related to colorectal cancer mortality versus mortality from other causes. METHODS: Patients over 65-year-old diagnosed with colorectal cancer between 2000 and 2014 were extracted from Surveillance, Epidemiology, and End Results (SEER) linked database. RESULTS: A total of 136,872 patients with colorectal cancer met the inclusion criteria. The median follow-up time was approximately 3 years. Forty-five point seven percent of them were alive at the end of follow-up, and colorectal cancer still accounted for the most cases of deaths. However, patients with tumor of Grade I or TNM stage I-II were more likely to die from other causes. The fully-adjusted relative hazards ratio (HR) shows age, gender, tumor site, chemotherapy, tumor characteristics of grade and TNM stage affected both types of mortality. Race only affected mortality of other causes. Cardiovascular disease (CVD) was a noticeable cause of death among patients with stage I colorectal cancer. With longer follow-up, deaths due to colorectal cancer decreased while deaths of CVD, pulmonary diseases and other cause of death increased. CONCLUSIONS: Colorectal cancer still accounts for most deaths in elderly patients. However, comorbidities including CVD/COPD were associated with the deaths of colorectal cancer patients over 65. As survival time increases, comorbidities should be considered for cancer treatment. Management of CVD/COPD among elderly patients can help improve overall survival (OS) in colorectal cancer.