BACKGROUND: Overall, colorectal cancer (CRC) incidence in the US has decreased over the last 30 years, yet it has increased in patients younger than 50. Cancers in this population are more aggressive and advanced at diagnosis. Our goal was to determine if screening should begin at a younger age. To accomplish this, we analyzed the rates of change in CRC incidence, and compared the incidence with that of cervical cancer (CC), which is screened earlier. Locations of CRC were compared to determine the appropriate screening method.
STUDY DESIGN: Incidence statistics were obtained from the Cancer Query System of the SEER database. Data were obtained from 1987 to 2006 in age groups of 5-year increments from 0 to 4 years old to 85+ years old for incidences of colon, rectal, and overall CRC. Combined data from 2002 to 2006 were queried to determine the locations of tumors and the overall incidence of CRC and CC at different ages.
RESULTS: Across age groups 20 to 49, CRC incidence was higher in 2006 than in 1987. The most significant increase was from age 40 to 44, where CRC increased from a low of 10.7 per 100,000 in 1988 to 17.9 per 100,000 in 2006 (67%). Colon and rectal cancer increased 56% and 94%, respectively. People older than 50 had decreasing incidences. Approximately 30% of cancers in patients aged 35 to 49 occurred proximal to the splenic flexure. The incidence of CRC cancer equaled and subsequently surpassed CC in the 40 to 44 age group.
CONCLUSIONS: The most significant increase in CRC has occurred in patients ages 40 to 44. Patients over 50 continued to see a decline. Many of these cancers would be missed with sigmoidoscopy. Consideration should be given for age-based colonoscopic screening beginning at age 40, an age at which the incidence mirrors other accepted screened cancers.