Increasing age-related survival gap among patients with colorectal cancer: a population-based retrospective study

Background Survival for patients with colorectal cancer (CRC) has improved over the past decades. However, it is unclear whether older patients have benefited to the same extent as younger patients. Methods The Surveillance, Epidemiology, and End Results (SEER) 9 registries database was queried for CRC patients from 1975 to 2009. We presented yearly data for survival with overlying loess-smoothing lines across all age groups. Another cohort was created using the SEER 18 registries database for patients diagnosed with CRC from 1973 to 2014. Yearly data for surgery-performed rate, stage proportion, and multivariate hazard ratio were performed with overlying smoothing lines across all age groups. Results In the analysis SEER 9, 5-year cause-specific survival (CSS) of patients aged <= 54, 55-64, and 65-74 years showed robust increase since 1975; however, the survival of patients aged 75-84 years remained low despite modest improvement, and patients aged 85 or older even showed no survival gains since 1990. In the analysis of SEER 18, there has been a steady increase in the survival of patients aged <= 54, 55-64, 65-74, and 75-84 years as time period advanced; however, of CRC patients aged >= 85 years, the survival curves of period 1990-1999 and 2000-2012 could not be distinguished from each other presented with negligibly a small gap from the curve of 1980-1989. Conclusions The strong interaction between age and year of diagnosis implies that older patients have benefited less over time than younger patients, especially for patients aged >= 85 years.