Colorectal Carcinoma

Carol A. Burke

RAPID BOARD REVIEW—KEY POINTS TO REMEMBER:

ETIOLOGY AND RISK FACTORS
- A total of 80% of colorectal cancers are believed to arise from adenomatous polyps. As much as 20% to 30% of colorectal cancer are believed to arise from sessile serrated polyps.
- Sessile serrated polyps are neoplastic colorectal lesions and must be removed in their entirety.
- Approximately 70% of newly diagnosed colorectal cancers arise in patients without known risk factors.
- Risk Factors: personal history of polyps/cancer, first-degree relative < 60 or two first-degree relatives of any age, inflamatory bowel disease, inherited colorectal cancer syndromes
- Inherited colorectal cancer syndromes: familial adenomatous polyposis (FAP), Gardner syndrome, hereditary nonpolyposis colon cancer (HNPCC), Lynch syndrome
COLORECTIAL CANCER SCREENING

1. Colorectal cancer screening decreases colorectal cancer incidence and mortality

2. Screening Modalities: Fecal occult blood test, sigmoidoscopy, Stool DNA, CT Colonography, Colonoscopy

3. USPSTF Guidelines (2008): In average-risk individuals, start screening with annual high sensitivity guaiac testing, Colonoscopy every 10 years or flexible sigmoidoscopy every 5 years

i. New colorectal cancer screening guidelines recommend high sensitivity guaiac-based FOBT or FIT instead of low sensitivity guaiac-based options for testing.

4. Family history of colon cancer: Colonoscopy every 5 years starting at age 40 or 10 years younger that the age at which the relative developed cancer.

5. Ulcerative or Crohn colitis: Colonoscopy every 1 to 2 years after 8 years of pancolitic disease.

6. Familial adenomatous polyposis: Yearly screening beginning at puberty.

7. Hereditary nonpolyposis colon cancer: Colonoscopy every 1 to 2 years from age 25 to 40 years and then yearly screening
TREATMENT
- For most early-stage tumors (e.g., stages I and II) surgery alone is curative
- Adjuvant therapy for patients with stage III colon cancer improve overall and disease-free survival
SURVEILLANCE
- Colon cancer: surveillance examination should occur within 1 year and, if results are negative at that time, 3 years, and, if normal, every 5 years thereafter.
- Colon polyps in average-risk patients
  - 1 to 2, < 1 cm, tubular adenomas: 5 to 10 years recheck
  - ≥ 3, or ≥ 1 cm, or advanced adenoma: 3 year recheck

SUGGESTED READINGS

Ahnen D. The American College of Gastroenterology Emily Couric Lecture- The adenoma-carcinoma sequence revisted: Has the era of genetic tailoring finally arrived? Am J Gastroenterol. 2011:106;190-198.

Ahsan H, Neugut A, Garbowski G, et al. Family history of colorectal adenomatous polyps and increased risk for colorectal cancer. Ann Intern Med. 1998;128:900-905.

Algra AM, Rothwell PM. Eff ects of regular aspirin on long-term cancer incidence and metastasis: a systematic comparison of evidence from observational studies versus randomised trials. Lancet Oncol. 2012;13:518-527.

Atkin WS, Edwards R, Kralj- Hans I, et al. Once-only flexible sigmoidoscopy screening in prevention of colorectal cancer: a multicentre randomised controlled trial. Lancet. 2010;375: 1624-1633.

Baron JA, Beach M, Mandel JS, et al. Calcium supplements for the prevention of colorectal adenomas. N Engl J Med. 1999;340: 101-107.

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