Colorectal Cancer

Happy Monday, and welcome to Medical Mondays! Since March is Colorectal Cancer Awareness Month, that’s what this week’s topic is on!

Colorectal cancer is a neoplasm of the large bowel or rectum, most commonly adenocarcinoma, and the 3rd most common cancer in both men and women.

Risk Factors

• Age (usually >50yo)
• Inflammatory bowel disease
• Family history
• Personal history
• Inherited polyposis syndromes (e.g. familial adenomatous polyposis, Lynch syndrome)
• History of polyps (esp. adenomatous and/or villous)
• Lifestyle (smoking, alcohol, obesity, high-fat + low-fiber diet)

Clinical Presentation

How colorectal cancer presents tends to depend on the location of the neoplasm (right colon vs. left colon).

Right side bleeds. Left side blocks.”

Tumors of the left colon tend to present with signs of obstruction. They can be asymptomatic, but if symptoms are present, they are usually related to bowel obstruction:

• Change in bowel habits
• Decreased stool caliber
• Abdominal pain + distention
• Vomiting

Tumors of the right colon present with signs of active bleeding or blood loss. They commonly present with fatigue due to iron-deficiency anemia.

Any newly-developed iron-deficiency anemia in a post-menopausal woman or older man is highly suggestive of colorectal carcinoma.

Complications

• Intestinal obstruction
• Recurrence
• Metastasis (most commonly to the liver due to the rich portal circulation)
• Development of a second primary cancer

Diagnosis/Prognosis

Colonoscopy with biopsy is the gold standard for diagnosis. Colorectal adenocarcinomas consist of dysplastic columnar cells with different degrees of epithelial differentiation.

Prognosis is based on TNM tumor staging.

• Tumor invasion
• Lymph Node involvement
• Metastasis

 

 

The Duke Classification System can be used for determining prognosis based on a given tumor stage:

Treatment/Prevention

• Resection if cancer is localized
• Chemotherapy may be appropriate if there is lymph node involvement

Prevention mainly consists of cancer screening and surveillance based on a patient’s age and number of risk factors.

For patients with no family history of colorectal cancer and no signs or symptoms, the U.S. Preventive Services Task Force recommends one of the following from ages 50-75:

• Fecal occult blood test (FOBT) annually
• FOBT every 3 years + flexible sigmoidoscopy every 5 years
• Colonoscopy every 10 years* (much more sensitive than sigmoidoscopy; preferred screening method)

*If a first-degree relative has colorectal cancer, colonoscopy is recommended at 40, or 10 years before the age at which the relative was diagnosed. Repeat every 3-5 years.

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Disclaimer: This is where I reiterate that I am merely a medical student struggling through the world that is her clinical rotations. The statements made on this blog should not be taken as medical advice to treat, cure or prevent any disease. Please contact your own physician or health care provider before starting a health or fitness/wellness program. (See full disclaimer here.)