Blood test for early lung cancer shows promise

By Megan Rauscher

NEW YORK (Reuters Health) - The pattern of active genes in white blood cells can accurately distinguish people with early-stage lung cancer from cancer-free people, researchers report. They are hopeful that such a test may one day be used alongside lung CT scanning in patients with suspected lung cancer.

The findings were reported Monday at the meeting of the American Thoracic Society underway in Toronto. Dr. Anil Vachani and colleagues of the University of Pennsylvania in Philadelphia measured the number and different levels of genes expressed in lymphocytes (which normally make up about 50 percent of white blood cells) from 44 patients with early-stage lung cancer and 52 "control" subjects matched for age, smoking, gender and race.

In an interview with Reuters Health, Vachani said: "The hypothesis is that the lymphocytes are able to interact with all organs of the body and therefore interact with the tumor." The tumor interaction affects gene activation patterns in those lymphocytes, and "we can pick up these differences between people who have cancer and those who do not."

The researchers found that differences in just 15 genes could differentiate patients with early lung cancer from controls "with reasonable accuracy, about 87 percent," Vachani said.

Future trials are planned, he said, "to refine the accuracy, because we think 87 percent is very good but it still needs to get better."

A diagnostic blood test for lung cancer would have important implications, Vachani noted. "The big down side to screening for lung cancer with low-dose CT is that a lot of people are found to have abnormalities, which is usually not cancer."

In fact, in the US, "somewhere between 30 and 50 percent of patients will have a nodule or shadow on CT, but less than 1 percent will actually have cancer."

So most of the suspicious findings seen on a CT scan are benign, but they need to be checked out. "We think a peripheral blood test can fit in nicely at that stage; if someone has an abnormality on CT before doing a biopsy you might want to do a blood test to differentiate which ones actually might have cancer," Vachani explained.