What is the approach to managing a patient with suspected colorectal (colon and rectal) carcinoma?

Management of Suspected Colorectal Carcinoma

The management of suspected colorectal carcinoma requires a multidisciplinary approach with comprehensive diagnostic workup, staging, and treatment planning based on disease extent, with the goal of reducing mortality and improving quality of life through appropriate surgical resection and adjuvant therapy. 1

Initial Diagnostic Workup

• Complete colonoscopy is essential for diagnosis and to rule out synchronous lesions 1
• Pathology review of any biopsied or resected specimens is required to confirm invasive cancer 1
• Laboratory tests should include CBC, platelets, chemistry profile, and CEA level 1
• Chest, abdominal, and pelvic CT scans are necessary for staging 1
• Endorectal ultrasound and/or pelvic MRI are recommended for rectal cancer to assess local invasion and guide preoperative treatment decisions 1
• PET scan is not routinely indicated but should be considered before surgical resection for patients with suspected recurrence or isolated resectable metastases 1

Surgical Management

Colon Cancer

• En bloc resection with regional lymph node removal (at least 12 nodes should be examined) is the standard surgical approach for resectable colon cancer 1
• For obstructing tumors, options include:
  • One-stage colectomy with en bloc removal of regional lymph nodes 1
  • Resection with diversion for high-risk patients 1, 2
• For pedunculated or sessile polyps with invasive cancer:
  • If completely removed with favorable histological features and clear margins, observation may be sufficient 1
  • If margins cannot be assessed or unfavorable histological features are present, colectomy with lymph node removal is recommended 1

Rectal Cancer

• Total mesorectal excision (TME) is strongly recommended as it provides low local recurrence rates (<10%) 1
• Whenever possible, sphincter-preserving surgery (low anterior resection) should be employed 1
• For early T1 rectal cancers meeting specific criteria, transanal excision may be appropriate 1
• For locally advanced or fixed tumors, preoperative chemoradiotherapy followed by radical surgery is recommended 1

Neoadjuvant and Adjuvant Therapy

Colon Cancer

• Stage III (node-positive) patients should receive adjuvant chemotherapy with fluoropyrimidine-based regimens 1
• Options include 5-FU/leucovorin, FOLFOX (5-FU/leucovorin/oxaliplatin), or CapeOX (capecitabine/oxaliplatin) 1, 3
• Selected high-risk stage II patients may also benefit from adjuvant chemotherapy 1

Rectal Cancer

• Preoperative therapy is preferred over postoperative therapy as it is more effective and less toxic 1
• For locally advanced rectal cancer (T3-T4 or node-positive):
  • Preoperative radiotherapy (25 Gy in 5 fractions) followed by immediate surgery, or
  • Preoperative chemoradiotherapy (50 Gy with concurrent 5-FU) followed by surgery after 6-8 weeks 1
• Postoperative chemoradiotherapy should be considered for patients with positive circumferential margins or perforation if preoperative therapy was not given 1

Management of Metastatic Disease

• For resectable synchronous liver or lung metastases:
  • Colectomy with synchronous or staged resection of metastases, or
  • Neoadjuvant chemotherapy followed by staged resection 1
• For unresectable metastases:
  • Systemic therapy with FOLFOX or FOLFIRI with or without targeted agents 1, 4
  • For KRAS/NRAS wild-type tumors, anti-EGFR antibodies (cetuximab, panitumumab) may be added 5, 6
  • For BRAF V600E mutation-positive metastatic CRC, cetuximab in combination with encorafenib is recommended 5
  • Re-evaluation for conversion to resectable disease should be performed regularly 1, 6

Surveillance After Curative Treatment

Colon Cancer

• History and physical examination every 3 months for 2 years, then every 6 months for the next 5 years 1
• CEA testing (if elevated at baseline) every 3 months for 2 years, then every 6 months for 2-5 years 1
• Colonoscopy within 1 year of resection (or 3-6 months postoperatively) 1
  • If polyps are found, repeat annually
  • If no polyps, repeat every 3-5 years 1
• CT scans should be used only when there are clinical indications of possible recurrence 1

Rectal Cancer

• History and rectosigmoidoscopy every 6 months for 2 years 1
• Complete colonoscopy within the first year if not done at diagnosis 1
• Liver ultrasound every 6 months for 3 years and at years 4 and 5 may be considered 1

Management of Recurrence

• For elevated CEA or suspected recurrence:
  • Colonoscopy, chest/abdominal/pelvic CT scans, and physical examination 1
  • PET scan should be considered before surgical resection for suspected recurrence 1
• For isolated recurrences (anastomotic site, liver, or lung):
  • Surgical resection should be considered if potentially curative 1
• For local rectal cancer recurrence:
  • Preoperative chemoradiotherapy (if not previously given) followed by radical surgery 1
• For unresectable recurrence:
  • Systemic chemotherapy with FOLFOX, FOLFIRI, or other appropriate regimens 1, 4

Special Considerations

• Molecular testing for RAS/BRAF mutations and microsatellite instability status is important for treatment planning in metastatic disease 5, 6
• Tumor location (right vs. left-sided) may influence prognosis and treatment response 7
• Clinical trials should be considered a priority option when available 1, 8
• For obstructing tumors, self-expandable metal stents may be used as a bridge to surgery in selected cases 2