Abstract
BACKGROUND: The incidence of rectal cancer in the United States in young patients is considered to be low. Underestimating this incidence may result in a failure to diagnose younger patients with rectal cancer in a timely manner. METHODS: The authors conducted a retrospective cohort study using Surveillance, Epidemiology, and End Results (SEER) cancer registry data. A total of 7661 patients with colon, rectal, and rectosigmoid cancer who were diagnosed at age <40 years were identified between 1973 and 2005. The change in incidence over time for colon and rectal/rectosigmoid cancer was calculated and the annual percent change for anatomic subsites of colorectal cancer compared. RESULTS: SEER data demonstrated an increase in the incidence of rectal cancer without any increase in colon cancer (annual percent change of 2.6% vs -0.2%). The difference was statistically significant and extended to rectosigmoid cancer, but not cancer of the sigmoid colon or descending colon (annual percent change of 2.2% vs 0.4% and -2.8%, respectively). Joinpoint analysis of the slope of the curve of rectal and rectosigmoid cancer incidence identified the beginning of the increase to be 1984. All races and both sexes demonstrated similar statistically significant increases in the incidence of rectal and rectosigmoid cancer. CONCLUSIONS: The incidence of rectal and rectosigmoid cancer appears to be increasing in patients aged <40 years. Patients presenting with rectal bleeding or other alarming signs or symptoms should be evaluated with this finding in mind.