Colon Cancer

Posted by Graham McMahon • June 25th, 2010

This week’s Case Record of the Massachusetts General Hospital is A 35-Year-Old Man with Adenocarcinoma of the Cecum.

As many as 15% of colorectal adenocarcinomas occur in patients younger than 50 years of age — the age when we routinely start screening for such cancers. Only 0.1% of all colon cancers occur in patients before 20 years of age, and 1% from 20 through 34 years of age.

Clinical Pearls

What familial syndromes need to be considered in young people with colorectal cancer?

In a young patient with colon cancer, hereditary forms need to be considered, including familial adenomatous polyposis, hereditary nonpolyposis colorectal cancer (HNPCC), and MutY homologue (MYH)-associated polyposis. All these syndromes are associated with early-onset colon cancer, but HNPCC-associated colon cancers are noteworthy for occurring in the right colon more often than in the left colon. Other factors that may predispose to colorectal cancer in the young include inflammatory bowel disease and a history of abdominal or pelvic radiation.

What new agents are available for the treatment of patients with metastatic colorectal cancer?

Bevacizumab is a monoclonal antibody that blocks the action of vascular endothelial growth factor and was approved by the Food and Drug Administration in 2004 for use in patients with metastatic colon cancer. Cetuximab is a monoclonal antibody directed against the epidermal growth factor receptor and was approved for use in patients with metastatic colorectal cancer that is refractory to irinotecan. Either of these agents may improve progression-free survival when added to standard chemotherapy, though the improvement is modest.

Morning Report Questions

Q: What are the advantages of initial surgical resection of the primary tumor in patients with metastatic colon cancer?

A: Laparotomy with resection of the primary tumor permits a thorough evaluation of the stage of the primary tumor and the extent of intraabdominal disease, since peritoneal carcinomatosis and very small metastases often cannot be visualized on imaging. Surgical resection also provides control of the primary tumor, thereby reducing the risk of bleeding, obstruction, or perforation during subsequent treatments.

Q: What are the disadvantages of initial surgical resection of the primary tumor in patients with metastatic colon cancer?

A: The major disadvantage of an up-front operation is the delay of chemotherapy, especially in cases in which a surgical complication (e.g., an anastomotic leak or wound infection) occurs. In addition, a postoperative bowel obstruction caused by adhesions can also delay or interrupt chemotherapy. According to the results of a meta-analysis, there was a major complication in 12% of patients who received surgical resection first, including obstruction, hemorrhage, sepsis, and an anastomotic dehiscence. Resection of the primary tumor is not associated with an overall survival advantage, and most patients will never have a complication from the primary tumor.

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