Definition
A.Screening for colorectal cancer (CRC) has increased early detection and has allowed for early intervention of premalignant localized cancer. There are multiple screening guidelines. Table 14.3 outlines current recommendations for colorectal screening for adults at average risk from the U.S. Preventative Task Force (USPTF), the American Cancer Society (ACS), and the U.S. Multi-Society Task Force (MSTF) on CRC. There are two categories of screening:
1.Stool-based testing.
2.Direct visualization tests.
Incidence
A.In the United States, CRC is the second leading cause of cancer-related death in both men and women.
B.Americans have a 5% lifetime risk of CRC.
C.CRC is rare before age 40 years.
D.90% of the cases of CRC occur after 50 years. The majority of cases are diagnosed between 65 and 74 with the average age of diagnosis at 68 and the average age of death at 73.
E.African Americans have a higher overall incidence rate and younger mean age at onset of CRC:
1.Lower screening rates.
2.Higher CRC incidence rate.
3.Earlier mean age at onset.
4.Worse survival and late-stage presentation.
5.Higher proportion of cancers before age 50.
F.Up to 20% of CRC in the United States is associated with smoking.
G.Obesity is associated with colon cancer but not increases in rectal cancer. Abdominal obesity is a stronger risk factor than truncal obesity or body mass index (BMI).
Pathogenesis
A.The usual pathogenesis is the development of a slow-growing adenomatous polyp followed by onset of dysplasia and finally cancerous cells.
Predisposing Factors
A.Age: 50 years and older.
B.Male gender.
C.African American.
D.Family history/genetic—account for 20 % of all CRCs:
1.Familial adenomatous polyposis (FAP).
2.Nonpolyposis CRC—Lynch syndrome.
3.MUTYH-associated polyposis (MAP).
4.Family history outside of genetic factors.
E.Smoking and moderate to heavy alcohol use (on average three drinks or more daily).
F.Obesity.
G.Diet high in red meat and fats.
H.Personal history of prior adenomatous polyps or isolated CRC.
I.Inflammatory bowel disease (IBD: Crohn’s disease [CD] and ulcerative colitis [UC]).
J.Diabetes/insulin resistance.
K.History of renal transplantation.
L.History of abdominal radiation.
Common Complaints
A.Asymptomatic screening.
Subjective Data
A.Review the patient’s age and risk factors to discuss screening for CRC.
B.Review family history of CRC.
C.Review smoking history and alcohol consumption.
D.Review the patient’s diet, evaluating red meat, processed meats, and lack of grains, fruits, and vegetables.
E.Review all medications currently being taken, including over-the-counter (OTC) and herbal products.
Physical Examination
A.Examinations are not required for discussion on colorectal screening testing.
B.A physical examination and vital signs should be taken as indicated for other presenting complaints.
Diagnostic Tests
A.Stool-based testing:
1.Guaiac-based fecal occult blood test (gFOBT).
2.Fecal immunochemical test (FIT).
3.FIT fecal DNA.
4.Multi-targeted stool DNA test (MT-sDNA).
B.Direct visualization tests:
1.Flexible sigmoidoscopy.
2.Colonoscopy: The American College of Gastroenterology (ACG) recommends the colonoscopy as the preferred strategy for screening.
3.CT colonography (virtual colonoscopy).
Differential Diagnoses
A.None related to screening.
Plan
A.Patient teaching:
1.Educate patient about modifying controllable risk factors with diet, exercise, smoking cessation, and low or no consumption of alcohol (on average one or less drinks per day).
2.Discuss the procedures and the preparation needed for each test.
B.Pharmaceutical therapy:
1.Bowel prep for flexible sigmoidoscopy and colonoscopy depends on the test, patient’s age, and other comorbidities.
2.Refer to Chapter 2 (Adult-Geriatric Assessments), Table 2.2 for the USPSTF recommendations for aspirin use to prevent cardiovasculor and colorectal disease recommendations by age range.
Follow-Up
A.Follow-up CRC screening is determined by family history, underlying risk factors, results of the prior screening test, the test used for screening.
B.Patients with classic FAP (>100 adenomas) should be advised to have genetic counseling.
C.Nonsteroidal anti-inflammatory drugs (NSAIDs) have been associated with a decrease in the risk of developing CRC. There is insufficient evidence to recommend the use of NSAIDs as a prevention strategy.
Consultation/Referral
A.Refer to a gastroenterologist and/or surgeon as indicated.
Individual Considerations
A.Geriatrics:
1.Medicare Part B covers colorectal screening tests. See Chapter 2 for the full Medicare coverage guidelines.