Colon and Rectal Cancers - Staging

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Bevacizumab administered intravenously along with IFL extends survival by about 5 months longer than IFL alone. Common side effects of bevacizumab include nosebleeds, fatigue, diarrhea, and high blood pressure. Less common side effects include stroke, heart attacks, angina, and formation of holes in the colon and stomach (gastrointestinal perforation).

Cetuximab. Cetuximab (Erbitux) was approved in 2004 for the treatment of metastatic colorectal cancer. This monoclonal antibody drug targets epidermal growth factor receptor (EGFR), a protein required by cancer cells in order to proliferate. It can be used either in combination with irinotecan or alone for patients who have not responded to irinotecan. Studies of the cetuximab-irinotecan combination suggest it can help in tumor shrinkage. It has a modest effect on survival, prolonging patients' lives by about an additional month or two. Recent guidelines recommend that cetuximab, and panitumumab (see below), should be given only to patients with tumors that express the wild-type KRAS gene. Patients with metastatic cancer should have tumors tested for KRAS gene status.

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Panitumumab. Panitumumab (Vectibix) was approved in 2006 for treatment of colorectal cancer that has metastasized following standard chemotherapy. Like cetuximab, panitumumab is a monoclonal antibody drug that targets EGFR. In clinical trials, panitumumab helped delay disease progression and prolong survival by about 3 months. About 8% of patients experienced tumor shrinkage. Common side effects of this drug include skin rash, fatigue, abdominal pain, nausea, and diarrhea or constipation. Serious side effects include pulmonary fibrosis, severe skin rash, and skin reactions at the infusion site.

Investigational Biologic Drugs

Tumor Growth Factor Inhibitors. Tumor growth factors, such as epidermal growth factor, stimulate cell growth. Cetixumab (Erbitux) and panitumumab (Vectibix) are the two currently approved colorectal cancer drugs that target the epidermal growth factor receptor (EGFR). Nimotuzumab (TheraCIM) is currently being studied in combination with irinotecan.

Tyrosine Kinase Inhibitors. Tyrosine kinase is an enzyme associated with EGFR that is involved with the signaling mechanisms that prompt cell growth. The EGFR/tyrosine kinase inhibitor erlotinib (Tarceva), which is approved for the treatment of pancreatic and lung cancers, is being investigated as an adjuvant treatment for metastatic colorectal cancer. Sunitinib (Sutent), which is approved for renal cell carcinoma, is another tyrosine kinase inhibitor in trials for colorectal cancer.

Review Date: 10/21/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).