Simple Blood Test May Detect Colon Cancer
Main Line Times - October 1999

Wynnewood - At the recent American Society of Colon and Rectal Surgeons Meeting in Washington, D.C., Dr. John H. Marks, M.D. of Lankenau Hospital presented the results of his year-long study on the early detection of colon and/or rectal cancer.

Dr. Marks, an international leader in the field of colorectal cancer, explained that a simple blood sample could detect the presence of peripheral epithelial or tumor cells.

The new technology employs monoclonal antibodies linked to an iron particle which is mixed with a simple blood sample. This is followed by the use of immunomagnetic and multiparameter flow cytometry separation to detect the abnormal presence of tumor cells. The study involved 44 patients with primary, recurrent or metastatic colorectal cancers and 27 controls.

For decades, medical researchers and physicians have been trying to find tests that can identify cancer in its earliest stages or persons at risk for the disease. Some research has pointed to possible markers such as the PSA for prostate cancer. Other research has led to DNA testing for genetic mutations so that people at risk could be identified.

But until now, screening for colorectal cancer has been hemoccults, sigmoidoscopies and colonoscopies.

"Although technology using blood tests has started to be investigated as a way to detect some cancers," said Dr. Marks, "this is the first time we have been able to qualitatively examine and quantify the number of actual cancer cells in the peripheral blood stream. The challenge has been to detect as few as five cancer cells in a background of 10 million blood cells. This is a potentially powerful tool to monitor treatment efficacy and colorectal cancer status. Of course, the results are still preliminary and we need to conduct prospective studies before the potential use of this test can be considered reliable for either screening or monitoring patients' responses to therapy and staging."