Colorectal Cancer: Screening and Surveillance Recommendations

From the Boston University School of Medicine, Boston, MA.

Abstract

• Objective: To review recommendations for colorectal cancer (CRC) screening.
• Methods: Review of the literature.
• Results: In the United States, CRC is the third most commonly diagnosed cancer and the third leading cause of cancer death. CRC screening can reduce mortality through the detection of early-stage disease and the detection and removal of adenomatous polyps. There are several modalities for CRC screening, with current technology falling into 2 general categories: stool tests, which include tests for occult blood or exfoliated DNA; and structural exams, which include flexible sigmoidoscopy, colonoscopy, double-contrast barium enema, and CT colonography. The preferred CRC prevention test for average-risk individuals is colonoscopy starting at age 50 with subsequent examinations every 10 years. Patients unwilling to undergo screening colonoscopy may be offered flexible sigmoidoscopy, CT colonography, or fecal immunohistochemical test. Surveillance examinations should occur based on polyp findings on index colonoscopy. There is no recommendation to continue screening after age 75, though physicians can make a determination based on a patient’s health and risk/benefit profile. Current guidelines recommend against offering screening to patients over age 85.
• Conclusion: Increasing access to and utilization of CRC screening tests is likely to lead to improvements in mortality reduction, as only about half of people aged 50 or older report having received CRC testing consistent with current guidelines.

In the United States, colorectal cancer (CRC) is the third most commonly diagnosed cancer and the third leading cause of cancer death in both men and women [1]. In 2014, an estimated 136,830 people were diagnosed with CRC and about 50,310 people died of the disease [2]. Colorectal cancer usually develops slowly over a period of 10 to 15 years. The tumor typically begins as a noncancerous polyp, classically an adenomatous polyp or adenoma, though fewer than 10% of adenomas will progress to cancer [3]. Adenomas are common; an estimated one-third to one-half of all individuals will eventually develop 1 or more adenomas [4,5]. In the United States, the lifetime risk of being diagnosed with CRC is approximately 5% for both men and women [6]. Incidence rates for CRC increase with age, with an incidence rate more than 15 times higher in adults aged 50 years and older compared with those aged 20 to 49 years [7].

Certain demographic subgroups have been shown to be at higher risk. Overall, CRC incidence and mortality rates are about 35% to 40% higher in men than in women. The reasons for this are not completely understood but likely reflect complex interactions between gender-related differences in exposure to hormones and risk factors [8]. CRC incidence and mortality rates are highest in African-American men and women; incidence rates are 20% higher and mortality rates are about 45% higher than those in whites. Prior to 1989, incidence rates were predominantly higher in white men than in African American men and were similar for women of both races. Since that time, although incidence rates have declined as a whole [9], incidence rates have been higher for African Americans than whites in both men and women This crossover likely reflects a combination of greater access to and utilization of recommended screening tests among whites (resulting in detection and removal of precancerous polyps), as well as racial differences in trends for CRC risk factors [10].