Colorectal Polyps Overview

Colonic Polyps Overview

• Colorectal polyps are grossly visible protrusions from the colorectal mucosa.
• Prevalence: 30% of middle-aged individuals and over 50% of the elderly population have colorectal polyps.
• Histopathologic classification includes non-neoplastic hamartoma, hyperplastic polyps, and adenomatous polyps (pre-malignant).

Pathophysiology

• Inactivation of the APC gene initiates early adenoma development.
• Activation of KRAS proto-oncogene leads to loss of DNA and adenoma expansion.
• Mutations in TP53 (tumor suppressor gene) facilitate invasion and colorectal carcinoma development.

Colorectal Adenomatous Polyps

• Classified into tubular adenomas (lowest cancer risk), tubulo-villous adenomas (intermediate risk), and villous adenomas (highest risk, recommend colonoscopy every year).
• Average malignant transformation timeline: 5-10 years.

Risk Factors

• Polyps are typically detected around age 50; screening age may be lowered to 45 in some regions.
• Significant risk factor includes age, with over 50% of elderly individuals found to have polyps upon autopsy.
• Family history of colorectal cancer necessitates early screening in first-degree relatives (e.g., if diagnosed at 48, screen relatives starting at 38).

Effects of COVID-19 Pandemic

• During the pandemic, screening for colorectal cancer dropped by 80-90%, leading to an increase in missed colorectal cancer diagnoses.
• Non-urgent medical care interruptions delayed essential screenings.

Detection and Screening

• Recommended for high-risk individuals to undergo screening without delay; those with a history of symptoms should consider colonoscopy.
• Common stool-based tests for average-risk individuals: FOBT (fecal occult blood test) and FIT (fecal immunochemical test).
• Imaging tests such as CT colonography can assist but are not replacements for colonoscopy if abnormalities are suspected.

Screening Recommendations

• Snare polypectomy is a common minimally invasive procedure used during colonoscopy to remove polyps.
• Colonoscopy is ideal for patients with concerning symptoms, especially those above age 50 or with a history of smoking.

Cost Utility Analysis in the Philippines

• Colorectal cancer screening is considered cost-effective as it saves lives.
• Current barriers include lack of insurance coverage for screening colonoscopy.
• Importance of follow-up screening for individuals with past bowel changes or family history of colorectal conditions.

Summary

• Colorectal adenomatous polyps are pre-malignant lesions, necessitating early detection to prevent cancer.
• Screening strategies are crucial, especially for high-risk individuals and those showing symptoms, with colonoscopy being the preferred diagnostic tool.

Histologic Classification of Adenomas

• Tubular Adenoma

  • Lowest risk of progressing to adenocarcinoma.
  • Recommended to repeat colonoscopy every 3-5 years for monitoring.

• Tubulo-villous Adenoma

  • Intermediate risk of evolving into adenocarcinoma.
  • Requires regular surveillance but with less frequency than the highest-risk type.

• Villous Adenoma

  • Highest risk of developing adenocarcinoma.
  • Strong recommendation for repeat colonoscopy within 1 year to detect any changes early.

Stool-based Tests Overview

• Two prominent stool-based tests for detecting gastrointestinal bleeding: FOBT (Fecal Occult Blood Test) and FIT (Fecal Immunochemical Test).

FOBT (Fecal Occult Blood Test)

• Detects peroxidase activity, indicating potential blood in stool.
• Results can be influenced by dietary factors:
  • Plant peroxidases, such as those in cauliflower, may produce false positives.
  • Consumption of red meat and vitamin C can alter accuracy, necessitating dietary restrictions prior to testing.
• Capable of detecting bleeding from the entire gastrointestinal tract.

FIT (Fecal Immunochemical Test)

• Utilizes antibodies to specifically detect globin, a component of hemoglobin.
• Does not require any dietary modifications, simplifying patient preparation.
• More focused than FOBT, as it detects colonic bleeding specifically, making it a more targeted test for colorectal issues.