Colorectal cancer CT

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: ; Roukoz A. Karam, M.D.[2], Saarah T. Alkhairy, M.D.

CT scan is used to determine the extent of involvement on colon cancer, most commonly in the abdomen and lungs.

Preoperative CT scan of the abdomen, and pelvis may be helpful in changing surgical planning after colorectal cancer has been diagnosed.

• Abdominal and pelvic CT scan provides identifies the extension of the tumor regionally, the presence of local or distant metastases, and the possibility of complications including perforation or obstruction.^[1]
• Preoperative CT scan of abdomen and pelvis should be reserved for stage II, III,or IV colorectal cancer patients, since scan in the early stages of the disease has a very low accuracy.^[2]

Preoperative CT scan of the Chest is not routinely performed; however, studies have identified a higher incidence of lung metastases in patients with rectal cancer compared to those with colon cancer.

• The higher incidence of lung metastases in rectal cancer patients is explained by the fact that the lower rectum’s venous drainage passes through the hemorrhoidal veins, bypasses the liver, and drains into the vena cava.^[3]

CT scan is used to determine the extent of involvement on colon cancer, most commonly in the abdomen and lungs. Findings on CT include:

• Luminal narrowing
• Marked wall thickening
• Circumferential thickening of the bowel wall
• Bowel obstruction and distension of the proximal bowel
• Involvement of surrounding structures
• Hepatic metastases
• Abnormal growth
• Intussusception
• Colonic perforation
• Gastrointestinal hemorrhage
• Enlarged lymph nodes
• Pulmonary metastases
• Peritoneal metastases
• Tumor recurrence

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