Doctors extract cancer cells from blood sample

By Gene Emery

BOSTON (Reuters) - An experimental process that snags lung cancer cells from a blood sample could give doctors real-time feedback on the most effective therapy, researchers reported on Wednesday.

Dr. Daniel Haber of the Massachusetts General Hospital Cancer Center and Harvard Medical School and colleagues were able to extract blood-borne cancer cells from 27 volunteers with non-small-cell lung cancer that had spread.

They found that changes in the number of circulating cancer cells correlated with the effectiveness of a patient's treatment and were also able to track genetic changes in the tumor cells over time.

The study, reported on the Web site of the New England Journal of Medicine, is another step in the quest for individualized medicine, where doctors strive to quickly assess a tumor, choose the most effective treatment, and alter that treatment as cancer cells adapt.

In December, the same group reported in Nature that their circulating tumor cells, or CTC, chip could extract malignant cells from people with breast, prostate, pancreatic and colorectal cancers, as well as lung tumors.

Now they say they have used the collected cells to identify specific mutations, which may someday help guide therapy.

"Right now you take your best guess as to what kind of treatment would work for a patient's cancer, give it to them for two or three months, and then repeat a CAT scan to see if it worked," Haber said in a telephone interview.

CONTINUOUS MONITORING

"If there were a way of measuring an earlier response, that would be fantastic," he added. "The CTC chip offers the promise of non-invasive continuous monitoring."

Doctors have many choices of drugs to treat lung cancer, the world's leading cancer killer, taking the lives of 1.2 million people a year -- 166,000 in the United States alone.

Yet only 15 percent of patients live five years or more.

"Treating patients with drugs specific to their particular tumor is likely to yield increased response rates, prolonged survival, and a decrease in the number of patients who are exposed to toxic drugs unnecessarily," Dr. Joan Schiller of the National Lung Cancer Partnership wrote in a commentary.

Schiller, of the University of Texas Southwestern Medical Center in Dallas, said there are practical questions about whether enough cells can be extracted to make the technique effective and whether it will work for other types of tumors.

Haber said he believes it will.

The CTC chip, licensed to the privately held CellPoint Diagnostics in Mountain View, California, is 100 times more sensitive than a U.S. Food and Drug Administration-approved technique that uses magnetic beads to try to extract cancer cells, according to Haber.