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Colorectal Cancer Screening

Posted Dec 09 2011 12:00am
Expert Insights (from Quest Diagnostics patient information page)

A Two-pronged Strategy for Combating Colorectal Cancer

Thursday, March 31st
By: John L. Marshall, MD
Category: Oncology

Colorectal cancer a disease that is preventable, treatable and beatable, and for which early detection is of paramount importance.

Last year, colorectal cancer (CRC) caused an estimated 51,370 deaths in the U.S1.

Most of those deaths could have been prevented.

“When colorectal cancer is detected early and treated, the 5-year relative survival rate is 90%,” notes Dr. John Marshall. “This drops to around 70% for patients diagnosed with regional disease and 12% for those diagnosed with end stage disease2.”

CRC is the third most common cancer in the U.S., but the second leading cause of cancer related deaths3. Dr. Marshall sees two keys to promoting survival from CRC: more widespread screening and more targeted therapy.

A glaring need for more widespread screening

“Colon cancer is one of those diseases where early detection clearly matters,” Dr. Marshall says. “Yet screening rates are terrible. Only 50% of Americans over 50 years of age receive any kind of screening for CRC. That compares with a screening rate for breast cancer of around 70%4. And it’s tragic because regular screening could prevent as many as 60% of CRC deaths.5”

Why are screening rates so low? "Partly because the tests for CRC are difficult for patients to undergo," says Dr. Marshall of colonoscopies and sigmoidoscopies. "Fecal tests help a little, but it's no fun to collect stool. People would rather have a needle stuck in their arm. Better screening techniques and early detection are critical. The field has been moving slowly, which is why recent developments, such as a DNA blood test, are important." This new blood test option, methylated Septin 9, is now available to aid CRC detection for the more than 52 million individuals over 50 years of age, who do not follow guidelines and remain untested.

Genetic profiling for more targeted therapy

In addition to advances in promoting more widespread screening, Dr. Marshall sees promise in targeted testing once CRC is diagnosed. “We give everybody the same treatment up front and just hope that it will help. But we don't know who will benefit.” he says, “We need to get smarter about who gets which drug. We should know which patients are at risk and who needs adjuvant chemotherapy. With stage 2 and 3 patients, for example, deciding who needs adjuvant therapy is critical.”

Dr. Marshall points to genetic profiling as a major step toward evaluating the risks and determining which treatments patients should receive. “Genetic testing is making its way into clinical practice and having an impact on therapy,” he says. “People are getting away from the microscope and looking at certain gene or protein expressions to understand which treatment to select.”

The promise of more effective treatment

Dr. Marshall is optimistic that advances in genetic profiling will lead to more effective therapies. “The only way we’re going to get more effective medicine is through this concept of molecular profiling and targeted drug development.”

"The hope is that this will lead to additional breakthroughs – not necessarily for everyone with colon cancer, but for subsets of patients with specific kinds of colon cancer. I expect we will start to see these efforts come to fruition over the next three to five years."

Testing for CRC via the ColoVantage test can be found online at (under Cancer markers/screening tests)


National Cancer Institute, U.S. National Institutes of Health

National Cancer Institute, U.S. National Institutes of Health

American Cancer Society, Cancer Facts & Figures 2010

American Cancer Society, Breast Cancer Facts & Figures 2010

National Health Interview Survey Public Use Data File 2000, 2003, 2005,and 2008.

Author contributing to Expert Insights:

John L. Marshall, MD

Professor of Medicine

Chief, Division of Hematology-Oncology

Director, Clinical Research

Lombardi Comprehensive Cancer Center

Georgetown University

Washington, DC

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