Definition:Colorectal cancer (CRC) screening aims to detect early-stage cancers or precancerous polyps in the colon or rectum, improving survival rates through early intervention.

Causes/Aetiology:

Genetic Factors: Family history, Lynch syndrome, familial adenomatous polyposis (FAP).
Lifestyle Factors: High red/processed meat diet, alcohol use, smoking, low physical activity.
Other Risk Factors: Inflammatory bowel disease (IBD), prior colorectal polyps or cancer.

Pathophysiology:CRC develops from abnormal cellular growth in the colon or rectum lining, often originating from adenomatous polyps. Mutations (e.g., in the APC gene) can transform these polyps into malignant tumors.

Symptoms:

Early Stage: Often asymptomatic, underscoring the importance of screening.
Advanced Stage: Blood in stool, weight loss, fatigue, abdominal pain, bowel habit changes, sensation of incomplete bowel evacuation.

Differential Diagnosis:

Irritable Bowel Syndrome (IBS): No blood in stool.
Hemorrhoids: Can cause rectal bleeding, typically painless.
Gastrointestinal Infections: May include diarrhea with blood and mucus.
Diverticulosis/Diverticulitis: Abdominal pain, bowel changes.

Investigations:

Faecal Occult Blood Test (FOBT): Detects blood in stool; recommended every 2 years for ages 50–74.
Colonoscopy: Gold standard for detecting polyps and cancers, used for high-risk individuals or positive FOBT.
Flexible Sigmoidoscopy: May supplement FOBT for screening.

Screening Guidelines:

Low Risk (<1% 10-year risk):
- 1st-degree relative >55 years: FOBT every 2 years from age 50–74.
- 1st-degree relative + 1 second-degree relative: FOBT every 2 years from age 50–74.
Moderate Risk (1–4% 10-year risk):
- 1st-degree relative <55 years: FOBT every 2 years from age 40–49.
- 2 first-degree relatives: Consider annual FOBT from age 40.
- 1st-degree + 2 second-degree relatives: Referral for colonoscopy, regular screening from age 50.
High Risk (>4% 10-year risk):
- 3 first-degree relatives: Screening from ages 35–44, colonoscopy every 5 years.
- 3 first/second-degree relatives (one <55 years): Referral to familial cancer clinic; follow high-risk screening protocols.
- Lynch syndrome: Annual screening from age 25 or as directed by genetic counseling.
- Large adenomas history: FOBT every 2 years from ages 35–44, colonoscopy every 5 years.

Risk Reduction:

Lifestyle: Reduce alcohol, stop smoking, maintain BMI 20-25, increase dietary fiber, and limit red/processed meats.
Aspirin: Low-dose (100 mg daily) from ages 50-70 may reduce CRC risk.

Management:

Low/Moderate Risk: Regular FOBT or colonoscopy per guidelines; positive results followed by diagnostic colonoscopy.
High Risk: Genetic testing and personalized screening via familial cancer clinic; frequent colonoscopy for early detection.

Complications:Advanced CRC can metastasize, especially to the liver, lungs, and other organs. Untreated polyps and adenomas can become cancerous.

Prognosis:

Early Detection: High survival rates with early treatment.
Advanced CRC: Prognosis is poorer, focused on symptom management.

Notes:

Lynch Syndrome: Associated with increased risks of colorectal, endometrial, gastric, and ovarian cancers.
Screening Frequency: Adjust intervals based on individual risk factors and family history.

Colorectal Cancer Screening Recommendations

Definition:

Colorectal cancer (CRC) is a malignant growth that occurs in the colon or rectum. It is the second most common cause of cancer-related deaths in Australia. Screening for colorectal cancer aims to detect early-stage cancers or pre-cancerous conditions (such as polyps), allowing for early intervention and improving survival rates.

Aetiology/Causes:

Genetic Factors: Family history of colorectal cancer, Lynch syndrome, familial adenomatous polyposis (FAP).
Lifestyle Factors: Diet (high in red/processed meat), alcohol consumption, smoking, and lack of physical activity.
Other Risk Factors: Inflammatory bowel disease (IBD), personal history of colorectal polyps or cancer.

Pathophysiology:

CRC develops from abnormal growth in the cells lining the colon or rectum. Initially, benign polyps may form, which can over time develop into malignant tumours. Genetic mutations such as in the APC gene lead to the development of adenomatous polyps, which are precursors to colorectal cancer.

Symptoms:

Early stage: Often asymptomatic, making screening essential.
Later stage: Blood in stool, unexplained weight loss, fatigue, abdominal pain, changes in bowel habits (diarrhoea or constipation), and a sensation of incomplete bowel evacuation.

Differential Diagnosis:

Irritable bowel syndrome (IBS): Symptoms overlap but IBS does not cause blood in the stool.
Hemorrhoids: Can cause rectal bleeding, but typically painless.
Gastrointestinal infections: Diarrhoea, blood, and mucus in stool.
Diverticulosis/Diverticulitis: Can present with abdominal pain and changes in bowel habits.

Investigations:

Faecal Occult Blood Test (FOBT): A screening test for blood in the stool, indicative of colorectal issues. Recommended every 2 years for individuals aged 50–74 years.
Colonoscopy: Gold standard for detecting colorectal polyps and cancers, especially for high-risk individuals or those with positive FOBT results.
Flexible Sigmoidoscopy: May be used in conjunction with FOBT for screening.

Screening Guidelines:

Low Risk (<1% 10-year risk):
- 1st-degree relative >55 years: Regular screening recommended via FOBT every 2 years from age 50–74.
- 1st-degree relative + 1 second-degree relative: FOBT every 2 years from age 50–74.
Moderate Risk (1–4% 10-year risk):
- 1st-degree relative <55 years: Screen starting at age 40, then every 2 years for FOBT until age 49.
- 2 first-degree relatives: Consider annual screening starting at age 40.
- 1st-degree + 2 second-degree relatives: Referral for colonoscopy, regular screening from age 50.
High Risk (>4% 10-year risk):
- 3 first-degree relatives: Screening starts from age 35–44, with colonoscopy every 5 years.
- 3 first/second-degree relatives (at least one <55 years): Referral to familial cancer clinic, screening as per high-risk recommendations.
- Lynch syndrome: Consider annual screening from age 25, or earlier as directed by genetic counseling.
- Colorectal cancer + large adenomas: Screening with FOBT every 2 years from 35–44 years, with colonoscopy every 5 years.

Risk Reduction:

Limit Alcohol Consumption: High alcohol intake is a risk factor for colorectal cancer.
Smoking Cessation: Smoking is a known carcinogen and contributes to colorectal cancer risk.
Maintain BMI (Body Mass Index) between 20–25: Obesity is associated with a higher risk of CRC.
Aspirin: Low-dose aspirin (100mg daily) for 2.5 years from ages 50–70 may reduce the risk of colorectal cancer.
Dietary Changes: Increase dietary fibre intake, particularly from fruits and vegetables, and reduce consumption of red/processed meats.

Management:

For Low and Moderate Risk: Regular FOBT or colonoscopy, as per guidelines. If results are positive, further diagnostic evaluation with colonoscopy is recommended.
For High-Risk Patients: Referral to a familial cancer clinic for genetic testing and individualized screening protocols. More frequent colonoscopy is recommended, with a focus on early detection of colorectal polyps or cancers.

Complications:

Advanced Colorectal Cancer: If not detected early, CRC can metastasize to the liver, lungs, and other organs.
Polyps and Adenomas: If not removed early, adenomas can develop into malignant cancers over time.

Prognosis:

Early Detection: If CRC is detected early, survival rates are high, and treatments are more effective.
Advanced CRC: Prognosis is poorer, with treatment focused on managing symptoms and prolonging life.

NOTES:

Lynch Syndrome: Considered high risk for colorectal cancer and associated with increased risks for other cancers like endometrial, gastric, and ovarian.
Screening Frequency: Screening intervals and modalities should be adapted based on the individual’s risk category.
Familial Cancer Clinics: Referral to these clinics for high-risk individuals ensures appropriate genetic testing and personalized care.

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