What is the best investigation for a male patient with a history of right hemicolectomy (surgical removal of the right side of the colon) 3 years ago for Colonic cancer (T1a, N0, M0) presenting with right lower quadrant pain, weight loss, and constipation for 3 months?

Best Investigation for a Patient with History of Right Hemicolectomy and Current Symptoms

For a male patient with history of right hemicolectomy for T1a, N0, M0 colon cancer presenting with right lower quadrant pain, weight loss, and constipation for 3 months, colonoscopy (option A) is the best investigation.

Rationale for Colonoscopy as First-Line Investigation

Clinical Context

• Patient has a history of early-stage colon cancer (T1a, N0, M0) treated with right hemicolectomy 3 years ago
• Current symptoms (right lower quadrant pain, weight loss, and constipation) are concerning for recurrence
• These symptoms specifically suggest possible anastomotic recurrence or metachronous lesion

Evidence-Based Recommendation

• The ESMO clinical practice guidelines strongly recommend colonoscopy as part of follow-up after colon cancer resection 1
• Colonoscopy must be carried out at year 1 and every 3-5 years thereafter to look for metachronous adenomas and cancers (Level III, B evidence) 1
• The Chinese Society of Clinical Oncology (CSCO) guidelines also include colonoscopy as a Grade I recommendation for follow-up after colon cancer surgery 1
• Colonoscopy is the preferred examination for patients with findings suspicious for colon cancer due to its ability to detect potential masses and obtain tissue for definitive diagnosis 1

Comparison with Other Imaging Modalities

CT Scan (Option B)

• While CT scans are recommended as part of routine surveillance (every 6-12 months for the first 3 years), they have limitations:
  • CT has low sensitivity (70.2%) for detecting early colon cancer 2
  • CT is more appropriate for detecting distant metastases rather than local recurrence at the anastomotic site

PET Scan (Option C)

• PET/CT is classified as a Grade III recommendation (lowest priority) in the CSCO guidelines 1
• PET is only recommended when there is clinical suspicion of recurrence while routine imaging is negative 1
• Not recommended as a first-line investigation for this clinical scenario

Ultrasound (Option D)

• Abdominal ultrasound is recommended as part of routine follow-up but has limited sensitivity for detecting colonic lesions
• More useful for liver metastasis detection than for primary colonic lesions or anastomotic recurrences

MRI (Option E)

• MRI has not been adequately evaluated for this specific indication 1
• While MRI has excellent soft tissue resolution, it is not the first-line investigation for suspected colonic recurrence

Follow-Up Algorithm After Initial Investigation

1. Start with colonoscopy to directly visualize the anastomotic site and remaining colon

   • Allows for biopsy of any suspicious lesions
   • Can detect both recurrence and metachronous lesions

2. If colonoscopy is negative or inconclusive:

   • Proceed with contrast-enhanced CT of chest, abdomen, and pelvis
   • Consider CEA testing if not already done

3. If CT is negative but symptoms persist:

   • Consider PET/CT for occult recurrence
   • Evaluate for non-cancer causes of symptoms

Important Considerations

• The patient's symptoms of right lower quadrant pain, weight loss, and constipation for 3 months are concerning for anastomotic recurrence
• Early detection of recurrence is critical as it may allow for potentially curative treatment
• Intensive follow-up including appropriate imaging has been associated with a 7-13% improvement in overall survival 3
• For this patient with T1a disease, the risk of recurrence is lower than for more advanced stages, but the concerning symptoms warrant thorough investigation

Colonoscopy provides the most direct visualization and ability to obtain tissue diagnosis, making it the most appropriate first investigation for this clinical scenario.