print

Looking for Cancer in a Blood Test: February 8, 2013

Imagine finding a single cancer cell among a huge sample of healthy cells. It’s next generation cancer technology being used in the real world.

“We now have a molecular test that can find one leukemia cell in like 100,000 normal cells. Very, very accurate. Which is fantastic way to follow patients,” says Dr. Lowell Hart, oncologist/hematologist on Lee Memorial Health System’s medical staff.

Since leukemia is a blood cancer, it is logical to test for it in the blood. Now doctors are looking for ways to detect minute blood cells that have broken away from a primary tumor and are circulating in the bloodstream. They’re called circulating tumor cells or CTC’s.

“Tumors will sometimes shed cancer cells in the bloodstream, sometimes not,” says Dr. Hart.

Prostate cancer patients may benefit from tests that screen for circulating tumor cells. 

“You put 7 1/2 CCs of blood through a flow cytometry machine and it’s pretty accurate for picking out how things are doing. It’s not good enough to diagnose the cancer for someone who walks off the street, but if a man has prostate cancer if that number of CTCs is going down you know they are responding to treatment. And if it’s going up they’re probably not responding,” says Dr. Hart.

For decades, doctors have relied on biopsies and snapshots like CAT scans to track the progress of cancer. This new line of blood testing offers a less invasive way monitor disease and find out what’s working.

“These tests will let us get away from doing so many CAT scans and giving everybody this radiation exposure. There really is tremendous effort towards making them more specific and being able to tell what’s going on inside,” says Dr. Hart.

CTCs are used in three common cancers: prostate, breast and colon.

“Both prostate cancer in men and breast cancer in women tend to metastasize. So if they travel and metastasize, they very often go to the bone and therefore to the bloodstream.  Colon cancer a little less so,” says Dr. Hart.

It may be years away, but oncologists hope to someday diagnose cancer, through a simple blood test.