Continued Rightward Shift of Colorectal Cancer

PURPOSE: Previous analyses of the time trends of colorectal cancer have suggested a shift from left-sided toward right-sided cancer sites. The aim of this study was to determine whether such trends in the subsite distribution of colorectal cancer could be confirmed in hospitalization statistics similarly as in the incidence data. METHODS: The inpatient files of the Department of Veterans Affairs and the Surveillance, Epidemiology, and End Result database of the National Cancer Institute were used to study the time trends of colorectal cancer in the United States during the past three decades. Any cancer location in the rectum, sigmoid, or descending colon was defined as left-sided colorectum. RESULTS: For the period between 1970 and 2000, the data from the Department of Veterans Affairs revealed a statistically significant 16 percent increase in the proportion of proximal lesions among white males and females, as well as a 22 percent increase in black males. For the period between 1973 and 1997, the data from the Surveillance, Epidemiology, and End Result revealed a 6 percent increase in the proportion of proximal colon cancers among whites and blacks of both genders. CONCLUSIONS: The epidemiologic data confirm a rightward shift in the colonic distribution of cancer.