What are the guidelines for a patient who tests positive for colon cancer?

Guidelines for Patients Who Test Positive for Colon Cancer

After a positive colon cancer diagnosis, patients should immediately be managed by a multidisciplinary team (MDT) that includes specialists from various disciplines who jointly analyze clinical manifestations, imaging, pathology, and molecular biology data to formulate the most suitable treatment strategy. 1

Initial Diagnostic Workup

Complete Staging Assessment

• Total colonoscopy (if not already done) to:
  • Confirm diagnosis with biopsy
  • Mark exact tumor location
  • Detect any synchronous lesions 1
  • If complete colonoscopy was not possible before surgery, it should be completed within 3-6 months after resection 1

Laboratory Tests

• Complete blood count
• Coagulation profile
• Liver and kidney function tests
• Serum albumin
• Carcinoembryonic antigen (CEA) - critical for baseline assessment and future monitoring 1
• Consider CA 19-9 (particularly useful for rectal tumors) 2

Imaging Studies

• CT scan of thoracic, abdominal, and pelvic cavities with intravenous contrast - primary imaging method for staging 1
• Contrast-enhanced MRI for:
  • Evaluation of locally advanced tumors
  • Defining ambiguous liver lesions
  • Assessment of rectal tumors and pelvic involvement 1

Molecular Testing

• MMR/MSI status - essential for treatment planning, especially for stage II disease 1
• Consider genetic screening for hereditary syndromes if family history is positive 1

Risk Assessment and Treatment Planning

Pathological Report Requirements

A comprehensive pathological report should include:

• Tumor site and size
• Macroscopic tumor perforation
• Histological type and grade
• Extension into bowel wall and adjacent organs
• Resection margins (proximal, distal, radial)
• Presence/absence of tumor deposits
• Lymphovascular/perineural invasion
• Tumor budding
• Number of removed and involved lymph nodes
• MMR/MSI status 1

Treatment Approach Based on Stage

Early Stage (Non-invasive/pTis)

• En bloc endoscopic resection of the polyp is sufficient 1

Early Invasive (pT1)

• Surgical resection with lymphadenectomy if high-risk features present:
  • Lymphatic or venous invasion
  • Grade 3 differentiation
  • Significant tumor budding 1

Localized Colon Cancer

• Surgical resection is the primary treatment
  • Laparoscopic colectomy can be safely performed when expertise is available 1
  • For obstructive tumors, one- or two-stage procedures may be used 1

Adjuvant Therapy Considerations

• Stage II: Adjuvant therapy for high-risk patients only
• Stage III: Oxaliplatin-based chemotherapy is standard of care 3
• Consider patient's age, comorbidities, and MMR/MSI status when planning adjuvant therapy 1

Follow-up Protocol

After completion of treatment, patients should undergo:

• Regular clinical examinations
• CEA monitoring
• Surveillance colonoscopy (timing depends on findings)
• CT scans as appropriate based on risk of recurrence

Special Considerations

Multidisciplinary Team Management

MDT management is especially important for:

• Patients with metastatic disease
• Patients with recurrent disease
• Patients with locally advanced disease
• Cases with difficult or controversial diagnosis and treatment decisions 1

Timing of Follow-up Colonoscopy

• If no adenoma recurrence is detected after initial treatment, follow-up interval can be extended to 3-5 years 1
• Patients with a history of colon cancer remain at high risk for metachronous cancers and require long-term surveillance 4

Common Pitfalls to Avoid

1. Failing to complete full colonoscopy examination when possible
2. Not obtaining baseline CEA levels before surgical intervention
3. Overlooking the need for genetic counseling in patients with family history
4. Delaying diagnostic colonoscopy after positive screening tests (should be completed within 60 days) 1
5. Not considering MSI/MMR status in treatment planning, especially for stage II disease

The management of colon cancer requires a coordinated approach with prompt implementation of diagnostic and therapeutic measures to maximize survival outcomes and quality of life.