Associations Between the Age at Diagnosis and Location of Colorectal Cancer and the Use of Alcohol and Tobacco

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Abstract
Colorectal cancer (CRC) remains the second leading cause of cancer deaths and in 2005 was projected to take the lives of 56 290 Americans.1 Given the insidious nature of CRC, with development of symptoms such as abdominal pain or bleeding typically signaling the presence of advanced incurable disease, screening the asymptomatic population is the only viable approach to curbing CRC fatalities. Two central issues in designing screening strategies are the timing of screening initiation and the choice of modality. Given the dramatic (almost logarithmic) rise in CRC incidence starting in the sixth decade of life, the onset of screening at age 50 years has generally been recommended for those deemed at “average risk.”2 However, CRC can occur before age 50 years. Indeed, in asymptomatic average-risk persons aged 40 to 50 years, the number of neoplastic lesions found on colonoscopic screening is not trivial (8.7% had tubular adenomas and 3.5% had advanced lesions).3 With regard to modality, flexible sigmoidoscopy every 5 years (coupled with annual fecal occult blood tests) and colonoscopy every 10 years have comparable cost-effectiveness and are viewed as equivalent options for screening.4 From an efficacy point of view, colonoscopy is superior to flexible sigmoidoscopy, because more than half of the patients with advanced proximal colonic lesions do not have a sentinel distal colonic polyp identifiable by flexible sigmoidoscopy.5 However, the advantages of flexible sigmoidoscopy include lower cost, decreased complication rates, and widespread availability, because it is generally performed by primary care physicians (as opposed to colonoscopy, which is generally performed by gastroenterologists or surgeons).