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Sunday, May 19, 2013
Increasing numbers of patients with advanced colorectal cancer are living longer, thanks in part to novel targeted drug therapies that work in conjunction with chemotherapy.
Targeted therapies are like 'smart bombs.' These drugs target the tumor and its surrounding environment, and spare most of the normal tissue from damage. Examples of targeted therapies for colorectal cancer include bevacizumab (avastin®), panitumumab (vectibix), and cetuximab (erbitux). These drugs are biologically engineered to attack cancer at its molecular roots.
Buoyed by recent successes, cancer researchers are working to improve the effectiveness of these drugs by testing different combinations and sequences of these drugs in clinical trials.
In recent years, the death rate from colorectal cancer has dropped while the average survival has increased - in some cases dramatically. Much of that success - particularly for those patients with advanced metastatic cancer that has spread outside their colon and rectum - can be attributed to the increased use of targeted therapies that attack cancer cells or their surrounding and leave healthy cells alone.
A number of studies published in the last couple of years reported the dramatic successes of bevacizumab, panitumumab, and cetuximab and have led to further clinical studies of targeted therapy in colorectal cancer. Those reports concluded that these targeted therapies are one of the most promising areas of cancer treatment and research.
Bevacizumab inhibits new blood vessels from forming around the tumor, which in turn makes the blood flow more efficient and chemotherapy delivery more effective in the initial stages of therapy. It also works on starving the tumor by cutting its blow flow in later stages.
Both panitumumab and cetuximab target a protein on the cancer and disables the epidermal growth factor receptor, which prevents cancer cell growth and makes the cancer cells more susceptible to chemotherapy.
All three targeted agents work really well, and researchers are now looking at combining them in different ways to see if they can add more benefit to cancer patients. Combining bevacizumab with traditional chemotherapy regimens can add an average of five months to survival. In some cases, however, survival has been extended three years or more. In fact, some colon cancer patients are five years out and still have a good quality of life.
About 150,000 people in the United States will be diagnosed with colorectal cancer this year, and more than 57,000 will die from it. Colorectal cancer is the second most common cancer in this country, accounting for about 10 percent of annual cancer deaths. Colorectal cancer refers to the presence of malignant cells in the colon or rectum, both of which are part of the large intestine. The tumors also may spread to other parts of the body.
Although the greatest advances in treating colorectal cancer in recent years have come from targeted therapies that seem to work best when combined with chemotherapy, early diagnostic screenings, along with preventive measures such as eating right and exercising more, also play a crucial role in improving survival outcomes.
This article is based on information provided by The Ohio State University Medical Center Media Relations Office and was adapted for use on NetWellness with permission, 2008.
Last Reviewed: Apr 01, 2008
Tanios Bekaii-Saab, MD
Assistant Professor of Medical Oncology
Associate Professor of Pharmacology
College of Medicine
The Ohio State University