- WEDNESDAY, July 2 (HealthDay News) — A new technique for finding
and analyzing stray cancer cells in the blood of lung cancer patients may
make it possible for doctors to one day not only determine the genetic
“signature” of particular tumors but to monitor changes in those cells and
adjust treatments accordingly.

“I think this is key to personalized medicine,” said Dr. Daniel Haber,
senior author of a paper detailing the technology, to be published in the
July 24 issue of the New England Journal of Medicine but released
early online Wednesday. “As we get to targeted therapies in increasing
numbers, and increasing understanding about the genetics that guide
targeted therapies, we need a way to know what we're treating.”

The “CTC chip” technology described in the new paper may also one day
aid in the detection of cancers that are likely to spread. “This is an
early warning sign we could use for earlier detection,” said Haber, who is
director of the Massachusetts General Hospital Cancer Center in
Boston.

A previous study published in Nature used the CTC (Circulating
Tumor Cells) chip technology to look at CTCs in lung, pancreatic,
prostate, breast and colon cancers. The CTC chip successfully found such
cells in 99 percent of the samples.

“We're very interested in the biology of these cells because no one has
really been able to study metastasis [spread of cancer to other parts of
the body] in action,” Haber said. “These are the cells that cause
metastases and the lethality of cancer. Now that we can identify and
purify them in decent numbers, we can study and hopefully identify some of
their vulnerabilities. It opens up a whole field of human metastasis and
human therapies.”

The CTC chip is a silicon chip about the size of a business card that
has 80,000 “columns” coded with an antibody that acts like a “glue” to
capture tumor cells “that have no business being in the blood,” Haber
explained.

Haber and his colleagues analyzed blood samples from 27 patients with
non-small cell lung cancer, 23 who had EGFR gene mutations and four who
did not. CTCs were identified in all samples and in genetic analyses from
mutations 92 percent of the time.

Mutations in EGFR, a protein, can help predict whether these tumors
will respond to a family of drugs called tyrosine kinase inhibitors.

“Even in the three to four months that we followed patients, the
genetic make-up of the tumors changed. Resistant mutations appear and
other mutations appear, obviously because we're doing things [with drug
therapy] to the cancer,” Haber said. “But the way we practice oncology we
don't typically test for that. We do one biopsy which takes a tiny, tiny
amount and assume that for the rest of the course, the tumor is the
same.”

“It's important to know in real time what you're treating,” he
continued. “We need to be able to follow the patient without needing to
re-biopsy the tumor every time.”

The technology is in its infancy, however. “This is still in a very,
very early stage where it takes a long time to handle every sample, to
flow the blood through the chip,” Haber said. “This is a proof of
principle that we can do this. We need a much more automated system for
larger clinical trials.”

Dr. Len Horovitz, a pulmonary specialist at Lenox Hill Hospital in New
York City, said that “you have to have some circulating cells to do this
test, but it's very exciting because they're getting a genetic fingerprint
of a tumor which will tell an oncologist what therapy the tumor might
respond to or not respond to.

“It's expensive, but it may well be that if we can identify patients
who can have a personalized regimen that works, we will be saving the cost
of treating all those patients with regimens that don't work,” he
added.

Two other studies looking at lung cancer are published in the July
issue of the Journal of Thoracic Oncology.

One, a review of existing studies, concluded that analyzing so-called
volatile organic compounds in the breath of lung cancer patients may hold
promise as a tool to detect cancer earlier. The technique deserves further
attention, said researchers from the Cleveland Clinic.

For the second study, researchers at the University of Alabama at
Birmingham found certain socioeconomic factors that may contribute to a
higher death rate among blacks with non-small cell lung cancer. These
included a higher smoking rate among blacks patients than white patients;
a greater delay to the start of treatment among blacks; and less
willingness to undergo chemotherapy among blacks than their white
counterparts.

More information

Visit the U.S. National Cancer Institute for more on lung
cancer.