The rise of proximal colorectal cancer: a trend analysis of subsite specific primary colorectal cancer in the SEER database.

backgroundColorectal cancer (CRC) is the third most common cancer worldwide and the second leading cause of cancer-related deaths. Given the significant prevalence of CRC, regular preventative screening is required. CRCs in different locations of the colon have variable molecular pathogenesis, gross appearance, and general disease outcomes. While the overall incidence of CRC has been decreasing, the decrease in proximally located CRC significantly lags behind the other forms of CRC. The objective of this study was to establish independent risk factors for proximal CRC for better identification of populations at risk for closer CRC monitoring and observation.

methodsA time-trend analysis was conducted using data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database from 1973-2007, comparing patient characteristics (age, sex, race/ethnicity, year of diagnosis, age of diagnosis, tumor grade, tumor stage, and urban-rural setting) between CRCs originating in different locations.

resultsAnalysis demonstrated that black race, female sex, age over 60, and being diagnosed in the 21st century (rather than 20th) were associated with an increased risk of proximal CRC compared to CRCs originating in other locations.

conclusionsOur study showed that black race, female sex, and age over 60 independently increased the likelihood of proximal CRC diagnosis. Furthermore, CRC trends identify an increasing proportion of all CRCs being of proximal origin. It is imperative that patients undergo regularly scheduled complete colonoscopies by trained endoscopists, especially if they belong to the high-risk groups previously identified.