Treatment Approach for Patients with New Diagnosis of Colon Cancer
For patients with newly diagnosed colon cancer, the standard treatment approach consists of surgical resection followed by adjuvant chemotherapy with FOLFOX or CAPOX regimens for stage III disease, with treatment duration of 3-6 months depending on risk stratification. 1
Preoperative Evaluation
Diagnostic Confirmation
- Total colonoscopy to confirm diagnosis and rule out synchronous tumors 2
Laboratory Assessment
- Complete blood count, liver and renal function tests 2
- Serum CEA level (important for baseline prognostic information and post-operative monitoring) 2
- Consider DPD genotype or phenotype testing before starting fluoropyrimidine therapy 1
Imaging Studies
- CT scan of thorax, abdomen, and pelvis with IV contrast (primary staging method) 2
- Contrast-enhanced MRI for:
- Evaluation of locally advanced tumors with surrounding structures
- Defining ambiguous liver lesions 2
- FDG-PET/CT not recommended for routine staging (limited added value) 2
Surgical Management
Surgical Approach
- En bloc colonic and mesenteric resection with wide margins (at least 5 cm from tumor) 2, 3
- Harvest at least 12 lymph nodes for accurate staging 2, 1
- Laparoscopic colectomy is a valid alternative to open surgery with:
Special Situations
- For obstructive colon cancers: one- or two-stage procedures as indicated 2
- For non-invasive (pTis) adenocarcinomas in polyps: en bloc endoscopic resection is sufficient 2
- For invasive carcinoma (pT1) in polyps: surgical intervention if high-risk features present 2
Post-Surgical Staging and Risk Assessment
- TNM staging system to determine prognosis and guide adjuvant therapy 2
- Assess MMR/MSI status before starting therapy (especially important for stage II patients) 1
- Additional risk factors to consider for stage II disease:
Adjuvant Chemotherapy
Indications
- Stage III (T1-4, N1-2, M0): Adjuvant chemotherapy recommended 1, 4
- Selected high-risk stage II: Consider adjuvant chemotherapy 2
- Stage I: No adjuvant chemotherapy indicated 1
Recommended Regimens
- FOLFOX: Oxaliplatin 85 mg/m² + leucovorin 200 mg/m² + 5-FU (bolus and continuous infusion) 4
- CAPOX: Capecitabine + oxaliplatin 1
- For patients who cannot tolerate oxaliplatin: Fluoropyrimidine monotherapy (infusional 5-FU/LV or capecitabine) 2
Treatment Duration
- Standard: Up to 12 cycles (6 months) 4
- Consider 3 months for low-risk tumors (T1-3, N1) 1
- 6 months offers superior benefit for high-risk tumors (T4 or N2) 1
- Start within 6 weeks of surgery for optimal benefit 1
Toxicity Management
- Monitor for peripheral sensory neuropathy with oxaliplatin 1, 4
- Consider prolonging oxaliplatin infusion time from 2 to 6 hours to mitigate acute toxicities 4
- Dose modifications for persistent neuropathy:
Follow-Up Recommendations
- History and physical examination every 3-6 months for 3 years, then every 6-12 months for years 4-5 2, 1
- CEA determination (if initially elevated) at same intervals 2, 1
- Colonoscopy at 1 year and then every 3-5 years 2, 1
- CT scans of chest and abdomen every 6-12 months for first 3 years in high-risk patients 2, 1
Common Pitfalls to Avoid
- Delaying adjuvant chemotherapy beyond 6 weeks after surgery reduces efficacy 1
- Underestimating the impact of oxaliplatin-induced neurotoxicity on quality of life 1
- Inadequate lymph node sampling (<12 nodes) leading to understaging 2, 1
- Routine use of FDG-PET for initial staging (not recommended) 2
- Overlooking synchronous lesions by not performing complete colonoscopy 2