Surgery Gastrointestinal Surgery

Colon cancer

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11 أقسام

intoduction

Colon cancer is a malignancy of the colon that typically affects individuals over 50 years old. Understanding its risk factors, presentation, and management is crucial for proper patient care.

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Background and Epidemiology

  • Colon cancer is a malignancy of the colon
  • Most patients are > 50 years old (25% have a positive family history)
  • Risk factors include: adenomatous and serrated polyps, familial cancer syndromes, inflammatory bowel disease, smoking and low fiber diet
  • This malignancy can arise in the right side or left side of the colon
  • Clinical presentation is dependent on the location of the tumor

 

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Risk Factors

Risk Factor Categories
Risk factors for colon cancer
Lifestyle factors
  • Frequent consumption of red/processed meat
  • Tobacco, alcohol use
Medical/family history
  • Diabetes/obesity
  • Prior abdominopelvic radiation
  • Ulcerative colitis
  • Inherited colon cancer syndromes (e.g., familial adenomatous polyposis, Lynch syndrome)
  • Personal/family history of adenomatous polyps or colon cancer
Protective factors
  • High fiber diet
  • Aspirin/NSAID use

 

Hereditary Cancer Syndromes
Common Hereditary Cancer Syndromes
Syndrome Associated Neoplasms
Lynch syndrome
  • Colorectal cancer
  • Endometrial cancer
  • Ovarian cancer
Familial adenomatous polyposis
  • Colorectal cancer
  • Desmoids and osteomas
  • Brain tumors
Von Hippel-Lindau syndrome
  • Hemangioblastomas
  • Clear cell renal carcinoma
  • Pheochromocytoma
Multiple endocrine neoplasm type 1
  • Parathyroid adenomas
  • Pituitary adenomas
  • Pancreatic adenomas
Multiple endocrine neoplasm type 2
  • Medullary thyroid cancer
  • Pheochromocytoma
  • Parathyroid hyperplasia (type 2A)
BRCA1 and BRCA2
  • Breast cancer
  • Ovarian cancer
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Clinical Presentation

  • Location-Based Symptoms
    1. Right-Sided Cancers (Cecum, Ascending Colon)
      • Exophytic mass
      • Iron deficiency anemia
      • Weight loss
      • Often silent until advanced
    2. Left-Sided Cancers (Descending, Sigmoid)
      • Infiltrating mass
      • Partial obstruction
      • Colicky pain
      • Hematochezia
      • Change in bowel habits
  • Common Presentations
    • Asymptomatic (discovered on screening)
    • Iron deficiency anemia
    • Change in stool caliber
    • Alternating bowel habits
    • Obstruction
    • Association with Streptococcus bovis
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Diagnosis

  • Colonoscopy and biopsy (begins at age 50 and then repeated every 10 years) → (gold standard)
  • “Apple core” lesion is seen on barium enema X-ray
  • CEA tumor marker: good for monitoring recurrence (should not be used for screening)
  • Fecal occult blood testing (FOBT) can also be used

 

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Staging

TNM Simplified
Colorectal Cancer Staging
Stage Location
Stage 1
  • Limited to mucosa and submucosa
Stage 2
  • Muscular and serosal layers
Stage 3
  • Lymph node involvement
Stage 4
  • Metastasis (most common etiology of liver metastasis)

 

Staging Evaluation for Rectal Adenocarcinoma
Tumor markers
  • Carcinoembryonic antigen (CEA)
Imaging
  • CT scan: chest, abdomen, and pelvis
Endoscopy/Direct Visualization
  • Colonoscopy
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Surveillance After Treatment

Surveillance After Colon Cancer Resection
Stage 1
  • Colonoscopy in 1 year and then every 3-5 years
Stage 2 & 3
  • Colonoscopy in 1 year and then every 3-5 years
  • Periodic CEA testing
  • Annual CT scan of the chest, abdomen (+/- pelvis)
Stage 4
  • Individualized
  • Consider Stage 2/3 strategy but with more frequent CT scans
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Treatment

  • Whenever possible, patients with adenocarcinoma of the colon should be offered surgical resection
  • When metastatic spread is confined to the liver, the surgical resection of both the hepatic mass and the primary tumor can be curative and increases long term survival
  • Combined chemotherapy and radiation are used for inoperable rectal adenocarcinoma as well as anal squamous cell carcinoma. However, radiation therapy is typically avoided in tumors proximal to the rectum (radiation enteritis can be severe)
Surgical Approaches
Location Procedure
Right Colon
  • Right hemicolectomy
Left Colon
  • Left hemicolectomy
Sigmoid
  • Sigmoid colectomy
Rectum
  • LAR (Low Anterior Resection)
  • APR (Abdominoperineal Resection)
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Follow-up

  • Surveillance Schedule
    • CEA every 3-6 months for 2 years
    • CT scan annually for 5 years
    • Colonoscopy at 1 year, then 3-5 years
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Clinical Pearls

  • Key Remember Points
    • Never ignore iron deficiency anemia
    • Location affects presentation
    • Early detection is crucial
    • Regular screening saves lives
  • Common Exam Topics
    • Right vs left sided symptoms
    • Staging workup
    • Screening guidelines
    • Surgical options
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Screening

  • Average Risk
    • Start at age 45
    • Colonoscopy every 10 years
    • Annual FIT test alternative
  • High Risk
    • Start 10 years before index case
    • More frequent intervals
    • Consider genetic counseling
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الدرس التالي Anal conditions (Anorectal disorders)
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