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

From the Guidelines

The best investigation for this patient is a Colonoscopy, as it is essential for directly visualizing the anastomosis site and remaining colon, allowing for biopsy of any suspicious lesions, especially given the patient's history of colon cancer and current symptoms of right lower quadrant pain, weight loss, and constipation three years after surgery. Given the patient's symptoms, which are concerning for recurrence, a thorough investigation is warranted. The initial cancer staging (T1a, N0, M0) indicates it was caught early with no lymph node involvement or metastasis, but the current symptoms necessitate a comprehensive workup. According to the Chinese Society of Clinical Oncology (CSCO) guidelines 1, colonoscopy is recommended as part of the follow-up contents for postoperative patients, emphasizing the importance of monitoring for local recurrence or metachronous lesions.

The patient's presentation with right lower quadrant pain, weight loss, and constipation suggests the need for a detailed examination of the abdominal cavity. While a CT scan of the abdomen and pelvis with contrast could provide valuable information on potential masses, lymphadenopathy, or metastatic disease, the CSCO guidelines suggest that contrast-enhanced chest-abdomen-pelvis CT is a Grade II recommendation, implying it may not be the first-line investigation for all patients but is considered for those with higher risk or suspicious symptoms 1.

Blood tests, including complete blood count, liver function tests, and carcinoembryonic antigen (CEA), should also be performed as part of the workup, as elevated CEA can suggest recurrence 1. However, the primary focus should be on direct visualization and assessment of the colon, given the patient's history and symptoms.

In terms of other investigations like PET/CT, it is only recommended for clinical suspicion of recurrence while routine imaging is negative, such as persistent elevation of CEA level 1. Ultrasonography of the liver and chest X-ray may also be considered but are not the primary investigations for this patient's presentation.

Therefore, prioritizing the patient's history of colon cancer, current symptoms, and the need for direct visualization of the colon, colonoscopy stands out as the most appropriate initial investigation, followed by other tests as indicated by the findings or persistence of symptoms.

From the Research

Best Investigation for Colonic Cancer Recurrence

The patient's symptoms of right lower quadrant pain, weight loss, and constipation 3 years after right hemicolectomy for colonic cancer (T1a, N0, M0) suggest a possible recurrence. The best investigation for this patient would be:

• PET-CECT scan: This is indicated for asymptomatic elevation of carcinoembryonic antigen (CEA) > 5 ng/ml and no obvious site of recurrence on clinical examination and basic imaging 2.
• Colonoscopy: Although the patient has a history of right hemicolectomy, colonoscopy is still essential for detecting any new lesions or recurrence in the remaining colon 3.
• Abdominal CECT: This can help identify any structural changes or lesions in the abdomen, including the bowel and surrounding tissues.

Rationale for PET-CECT

The use of PET-CECT is supported by studies that demonstrate its value in detecting recurrence in colorectal cancer patients:

• A study published in 2017 found that PET-CECT scanning had a sensitivity of 92.7%, specificity of 95.2%, positive predictive value of 96.2%, and negative predictive value of 90.9% in detecting recurrence 2.
• Another study published in 2006 found that whole-body PET/CT colonography was more accurate than CT alone in defining TNM stage, mainly due to its ability to accurately define T-stage 4.

Other Investigations

While other investigations like US and MRI may be useful in certain situations, they are not the primary choice for detecting colonic cancer recurrence:

• US: May be useful for detecting liver metastases, but its sensitivity and specificity are lower compared to other imaging modalities.
• MRI: May be useful for evaluating the extent of local recurrence, but its role in detecting distant metastases is limited compared to PET-CECT.