Change in onset age of first primary colorectal cancer in the USA.

Purpose: Identifying the onset age of cancer is essential for its early intervention. The aim of this study was to characterize the features and investigate the variation tendency of first primary colorectal cancer (CRC) onset age in the USA. Methods: For this retrospective population-based cohort analysis, data on patients diagnosed with first primary CRC (n = 330,977) between 1992 and 2017 were obtained from the Surveillance, Epidemiology, and End Results dataset. Annual percent changes (APC) and average APCs were calculated to examine the changes in average age at CRC diagnosis using the Joinpoint Regression Program. Results: From 1992 to 2017, the average age at CRC diagnosis decreased from 67.0 to 61.2 years, declining by 0.22% and 0.45% annually before and after 2000. The age at diagnosis was lower in the distal than in the proximal CRC cases and the age has the downward trends in all subgroups of sex, race, and stage. Over one-fifth of CRC patients were initially diagnosed with distantly metastatic CRC, with the age lower than that in localized CRC cases (63.5 vs 64.8 years). Conclusions: The first primary CRC onset age has decreased significantly in the USA over the last 25 years and the modern lifestyle may be responsible for the decline. Specifically, the age of proximal CRC is invariably higher than that of distal CRC. Moreover, the age of advanced stage is lower than that of the early stage. Clinicians should adopt earlier screening age and more effective screening techniques for CRC. [ABSTRACT FROM AUTHOR]