The first major field study of a new type of blood test to detect cancer early shows the technique can probably save lives, at least in certain circumstances.
A study in Hong Kong in which about 20,000 men were tested and then followed for three years found that nasopharyngeal cancer could be detected and treated early. That cancer, which grows in the throat, is exceptionally common in south China.
The result provides a peek at the promise and limitations of “liquid biopsies”—tests that may be able to spot tumor DNA in a person’s blood even before they have any overt symptoms.
The study, published by the New England Journal of Medicine, was carried out by the Chinese University of Hong Kong and led by Dennis Lo, a researcher who has played a pivotal role in the development of DNA blood tests, including those used for pregnant women.
Commercial interest in the cancer screening tests is mounting, with one U.S. company called Grail raising more than $1 billion to pursue the idea. Earlier this year, Grail merged with Cirina, a tiny startup founded by Lo, bringing it a number of important patents and letting it draw dramatically closer to commercialization.
Lo said his blood test isn’t available commercially yet in Hong Kong. Grail declined to reveal its commercial time line.
“We are planning to develop a screening test to help identify people at risk for this type of cancer in areas where it is common, initially in Hong Kong,” says a Grail spokesperson, Charlotte Arnold. “We are still in the planning stages and will provide more details at a later stage.”
Grail, a Silicon Valley startup, made a splash with its entry into the testing arena last year, including by hiring Jeff Huber, a prominent Google software executive, to be its CEO, initially suggesting a prominent role for computers and big data (see “Grail’s $1 Billion Bet on the Perfect Cancer Test”).
However, last week Huber relinquished the CEO role in an executive shuffle, though he retains a board seat.
The new report from Hong Kong highlights just how important smart and carefully executed medical studies will be to the new liquid biopsy technology.
The study there looked at nasopharyngeal cancer, which is closely associated with infection by the Epstein-Barr virus. Each tumor cell has as many as 50 copies of the virus’s genome inside it, and when these cells die, the virus’s genetic material is released into the bloodstream. There, it can be picked up with a simple, inexpensive genetic test costing around $30.
In 2013, Lo and a group of Hong Kong doctors began testing middle-aged Chinese men with no cancer symptoms for traces of the virus (see “10 Breakthrough Technologies, 2015: Liquid Biopsy”).
Of the 20,000 men they tested, 309 of them, or 1.5 percent, scored positive on the blood test. Of those, 34 were found to actually have nasopharyngeal carcinoma when a doctor checked them with an endoscope or an MRI.
That means one in 10 men who tested positive really had cancer, but didn’t know it.
At the same time, only one of the more than 19,000 men who tested negative have since developed the disease, meaning few true cases were missed.
Lo, in an e-mail, described as “remarkable” how often silent, early-stage cancers are being found and successfully treated, with few of those men progressing to advanced cancer. Normally, this type of cancer is detected fairly late, and survival rates are about 60 percent after five years.
While Lo seems to have proven that this liquid biopsy screening test really works, nasopharyngeal cancer is a special case. That is because the presence of the virus in tumor cells makes it much easier and cheaper to test for.
Lo estimates that, overall, it cost $28,600 to find each cancer case, mostly due to the cost of testing men who didn't end up having the disease.
Grail’s challenge is more difficult. It has been working on tests that use high-speed sequencers to search much more broadly through a person’s blood for hints of genetic material shed by tumors. Most of these, like lung or breast cancer, aren’t caused by viruses but by small mutations present in a person’s genome, which makes them more difficult and costly to detect.
In Grail’s laboratory, examining one person’s blood can easily cost $1,000—a price that could create huge expenditures if applied broadly as a public health measure as part of a screening program. By contrast, the simpler tests used by Lo in Hong Kong cost far less.
Lo’s study also highlights how important it is to test people already at high risk for cancer, as middle-aged Chinese men are for nasopharyngeal tumors.
While Grail’s founding goal is to develop a “pan-cancer” test able to spot many cancers at an annual checkup, the company is currently recruiting 120,000 women to provide blood samples, with the aim of developing a blood screening test for breast cancer.
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