Increased Frequency of Proximal Colon Cancer Among Non-Hispanic Blacks, Females, and Patients Age 60 and Older: ACG /Olympus Award

Abstract

Purpose: Cancers of the proximal colon have lagged behind distal and rectal sub-sites in terms of reduction in incidence over the last few decades, which is of concern given the more aggressive nature of these tumors. It is unknown if there are patient groups at increased risk for proximal lesions. Methods: We analyzed information of 505,141 patients included in the NCI Surveillance, Epidemiology and End Results datafile who had been diagnosed with primary, invasive colorectal cancer during 1973-2007 in order to identify trends in proximal colon cancer according to race/ethnicity, sex, age group, and geographic region. Results: The proportion of proximal cancers increased from 35.6% in 1973-1977 to 42.2% in 2003-2007 (P<0.001). As seen in the table, there is a marked step-wise increase in likelihood for proximal tumors in each of the five-year time periods culminating in an OR of 1.44 (95% CI 1.44-1.47) in 2003-2007 compared to the 1973-1978 period. Compared to Non-Hispanic Whites, the likelihood of proximal tumors was substantially higher among Non-Hispanic Blacks (OR=1.26, 95% CI 1.24-1.29) for Non-Hispanic Blacks whereas likelihood was significantly reduced among American Indians, Asian/Pacific Islanders and Hispanics. Additionally, females were about 40% more likely to have proximal tumors compared to males, and patients 60 years or older were about 50% more likely to have these lesions compared to younger patients. All findings remained significant in sub-analyses comparing rural versus urban populations and across SEER registries. Conclusion: This study found subgroups at possible increased risk for the relatively aggressive proximal colon cancer. Efforts to enhance colonoscopy screening rates in these patients may be warranted. Lastly, research is needed to identify behavioral or socioeconomic risk factors for these tumors.Table: No Caption available.