Blood Test Could Personalize Cancer Treatment with Fewer Side Effects

Headlines buzzed in January over the announcement of a next-generation blood test to detect cancer Researchers say it could eliminate the need for invasive biopsies, personalize cancer treatment, and improve quality of life.

Patients with advanced colon, breast and prostate cancer got a green light from the FDA to use the current version of the CTC (Circulation Tumor Cell) blood test only a few years ago. Some researchers are calling it a revolutionary tool for guiding treatment decisions and for predicting prognosis.

The Cleveland Clinic ranked it as the “Top Medical Innovation of 2009”, predicting “it will have a significant impact on health care.”

GYRIG rounds up opinion from doctors, scientists and the media who’ve
weighed on the technology’s impact on cancer care.

What’s the test? How does it work?

The CellSearch Circulating Tumor Cell (CTC) test currently in use with metastatic cancer patients counts the number of cancer cells shed by the primary tumor that circulate in the blood and spread to other parts of the body. The rise or decrease in these cells helps doctors determine in real time how a therapy is working.

Inventors say the test can:

• Detect a single cancer cell among a billion healthy ones

• Requires just a teaspoon of blood

• Can be performed quickly and repeatedly

The next-generation CTC test in development runs blood samples through a microchip with bristles to capture whole cancer cells shed by tumors that circulate in the blood, enabling researched to study their genetics.

While normal blood cells pass through, the circulating tumor cells stick to one of the 78,000 tiny posts coated with glue.

“It’s like a pinball machine – the blood has to flow through all of these columns to get to the other side,” said Dr. Daniel Haber, director of the Massachusetts General Hospital Cancer Center and and one of the test’s inventors.

Watch CTC Chip Dream Team video

Personalized cancer treatments

With the ease and speed of test results, doctors have expressed keen interest in its use as a tool chart personalized treatment for cancer patients.”That’s what got the scientific community’s interest,” said Dr. Mark Kris, lung cancer chief at Memorial Sloan-Kettering Cancer Center in New York. “Doctors can give a drug one day and sample blood the next day to see if the circulating tumor cells are gone.”

Compared to CTC test results in eight hours, doctors looking for tumor shrinkage after initiating treatment often have to wait several months with current tests such as the CT scan, MRI, X-ray, according to the Mayo Clinic.

“If you could find out quickly, ‘this drug is working, stay on it,’ or ‘this drug is not working, try something else,’ that would be huge,” said Haber.

Eric P. Winer, M.D., from the Dana–Farber Cancer Center and Harvard Medical School, expresses caution, saying, “I don’t feel the data [on CTCs] are sufficiently mature.”

Current use for metastatic colon cancer treatment

Currently centers like Georgetown University’s Lombardi Comprehensive Cancer Center, advanced CTC/molecular labs in Germany, and the Mayo Clinic use the CTC technology for monitoring and treating colon, breast and prostate cancer patients with metastatic disease (or cancer that has spread).

In a study published in Clinical Cancer Research, Dr. G. Thomas Budd, professor of medicine at the Cleveland Clinic in Ohio, reported that the “number of CTCs in the blood was a better indicator of disease progression than traditional imaging techniques such as computed tomography and magnetic resonance imaging; CTCs were more reproducible, were better predictors of survival, and estimated disease progression earlier.”

“It’s widely available and most insurance providers are covering it. Unfortunately I don’t think it’s being used as widely as it could be,” said Dr. Minetta Liu, a breast cancer specialist at the Lombardi Center who uses the CTC blood test routinely in her practice along with scans, and feels its aids day-to-day decisions with some patients.

The next-generation of CTC blood test in development by Massachusetts General Hospital and partner Johnson & Johnson, in trials right now with cancer patients at four medical centers in the United States, holds promise as a predictive blood test. As GYRIG examines in a second article, doctors could then see ahead of time which treatments would offer the best response based on genetic analysis of the cancer found, sparing the patient toxicity and side-effects from therapies that would be ineffectual.

Have you had experience with CTC blood tests? Or want to share your view?
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