Workup for Colon Cancer Investigations

Workup/Investigations for Colon Cancer

• Labs: Complete blood count (CBC); chemistry profile; liver function tests (LFTs); coagulation profile; serum carcinoembryonic antigen (CEA); genetic testing.
• Imaging: Crucial for staging.
  • CT Chest (non-contrast): Detects lung metastases (4-9% prevalence).
  • CT Abdomen and Pelvis (with contrast):
    • Staging sensitivity and specificity: T-stage (~77%, ~70%); N-stage (~64%, ~62%); M-stage (highly variable, >90% for liver, ~33% for peritoneal).
  • MRI Abdomen and Pelvis (with gadolinium): Used if CT is contraindicated; higher sensitivity and specificity for T-staging.
  • Urinary Tract Evaluation (IVP or cystoscopy): Necessary if urinary symptoms/large tumor.
  • PET CT:
    • Superior to standard CT for metastasis detection.
    • Potentially alters treatment in ~21% of patients.
  • Contrast-enhanced Ultrasound (CEUS):
    • Screening tool for liver metastases.
    • Used if CT/MRI is contraindicated or unclear.
    • Increased sensitivity for smaller liver lesions.

Treatment Paradigms for Colon Cancer

• Surgery: Option in all stages. Treatment depends on resectability and metastasis.
  • Resectable with no metastases: Surgery alone in Stages I and II; stages II with high-risk factors require adjuvant systemic therapy. Stage III patients require both surgical resection and adjuvant therapy. T4b tumors often require en bloc resection for adjacent organ involvement.
  • Resectable with metastases: Resect tumor and metastases; perioperative chemotherapy.
  • Unresectable: Systemic therapy, with or without surgery if needed for specific symptoms.

Resectable Disease Management

• Resectable tumors with no metastases:

  • Specific Considerations: Strategies for specific organ involvement during resections (bladder, liver, spleen, uterus/ovaries, abdominal wall, diaphragm, small bowel, non-regional nodes, para-aortic nodes, isolated peritoneal involvement, pancreas, and duodenum) with associated risks (mortality and morbidity).
  • Nodes: Nodes < 1cm² are considered normal; however, ~80% of nodal metastases are smaller than 5mm. Resection of isolated non-regional lymph nodes improves survival; however, routine extended lymphadenectomy is not always necessary. Para-aortic nodes (if isolated) and isolated peritoneal involvement (including resection of ovaries and tubes if peritoneal metastases are suspected) should be considered.
  • Pancreatic/Duodenal Involvement:
    • High risk for mortality.
    • Pancreaticoduodenectomy for pancreatic involvement (~8% of T4 tumors).
    • Partial duodenectomy or pancreaticoduodenectomy for duodenal involvement (~4% of T4 tumors).
  • Neoadjuvant therapy (T4b tumors):
    • Often variable results, but generally favorable compared to upfront surgery.
    • Increased R0 resection rate and survival.
    • Different treatment regimens depending on MMR (microsatellite mismatch repair) status (proficient/MSS vs. deficient/MSI-H).

• Resectable tumors with metastases: Evaluate resectability of metastases; surgical resection is indicated if possible, accompanied by perioperative chemotherapy; systemic therapy is the alternative if not resectable. Surgery for symptoms or need for local control.

This quiz covers the laboratory and imaging investigations essential for diagnosing and staging colon cancer. Focused on tests like CBC, liver function tests, and advanced imaging techniques, this quiz evaluates your understanding of effective cancer workups. Challenge yourself with questions regarding the specificity and sensitivity of various imaging modalities.