Study boosts hope of ‘liq­uid biop­sies’ for can­cer screen­ing

Tests boost early de­tec­tion and one mea­sure of sur­vival

The Hamilton Spectator - - HEALTH - MARILYNN MARCHIONE

Sci­en­tists have the first ma­jor ev­i­dence that blood tests called liq­uid biop­sies hold prom­ise for screen­ing peo­ple for can­cer. Hong Kong doc­tors tried it for a type of head and neck can­cer, and boosted early de­tec­tion and one mea­sure of sur­vival.

The tests de­tect DNA that tu­mours shed into the blood. Some are used now to mon­i­tor can­cer pa­tients, and many com­pa­nies are try­ing to de­velop ver­sions of these for screen­ing, as pos­si­ble al­ter­na­tives to mam­mo­grams, colono­scopies and other such tests.

The new study shows this ap­proach can work, at least for this one form of can­cer and in a coun­try where it’s com­mon.

“This work is very ex­cit­ing on the larger scale” be­cause it gives a blue­print for how to make tests for other tu­mour types such as lung or breast, said Dr. Den­nis Lo of Chi­nese Univer­sity of Hong Kong. “We are brick by brick putting that tech­nol­ogy into place.”

He led the study, pub­lished Wed­nes­day by the New Eng­land Jour­nal of Medicine. Lo is best known for dis­cov­er­ing that fe­tal DNA can be found in a mom’s blood, which launched a new era of non-in­va­sive test­ing for preg­nant women.

The study in­volved na­sopha­ryn­geal can­cer, which forms at the top of the throat be­hind the nose. It’s a good test case for DNA screen­ing be­cause it’s an ag­gres­sive can­cer where early de­tec­tion mat­ters a lot, and screen­ing could be tried in a pop­u­la­tion where the can­cer is most com­mon — mid­dle-aged Chi­nese men.

Also, the Ep­stein-Barr virus is in­volved in most cases, so tests could hunt for vi­ral DNA that tu­mours shed into the blood in large quan­ti­ties, rather than rare bits of can­cer cells them­selves.

About 20,000 men were screened, and vi­ral DNA was found in 1,112, or 5.5 per cent. Of those, 309 also had the DNA on con­fir­ma­tory tests a month later. Af­ter en­do­scope and MRI ex­ams, 34 turned out to have can­cer.

More cases were found at the ear­li­est stage — 71 per cent ver­sus only 20 per cent of a com­par­i­son group of men who had been treated for na­sopha­ryn­geal can­cer over the pre­vi­ous five years. That’s im­por­tant be­cause early cases of­ten are cured with ra­di­a­tion alone, but more ad­vanced ones need chemo­ther­apy and treat­ment is less suc­cess­ful.

Screen­ing also seemed to im­prove how many sur­vived with­out wors­en­ing dis­ease — 97 per cent at three years ver­sus 70 per cent of the com­par­i­son group.

Only one per­son who tested neg­a­tive on screen­ing de­vel­oped na­sopha­ryn­geal can­cer within a year.

The re­searchers es­ti­mate 593 peo­ple would need to be screened at a to­tal cost of $28,600 to iden­tify one can­cer case. It may be worth it in Hong Kong, but maybe not in places like the U.S. where the dis­ease is rare, and more peo­ple would have to be screened at a greater cost to find each case, said Dr. Richard Am­binder of Johns Hop­kins School of Medicine, who wrote a com­men­tary in the jour­nal.

Still, “this is show­ing that liq­uid biop­sies have great prom­ise,” he said. “This is an ad­vance that will in­deed save lives.”

The study was spon­sored by an Asian foun­da­tion and the Hong Kong gov­ern­ment. Lo and some other au­thors founded Ci­rina, a Hong Kong-based com­pany fo­cused on early can­cer de­tec­tion, and get roy­al­ties re­lated to DNA blood tests. In May, Ci­rina merged with Grail Inc., a Cal­i­for­nia com­pany work­ing on can­cer screen­ing blood tests with more than $1 bil­lion from drug com­pa­nies and big­name in­vestors such as Jeff Be­zos and Bill Gates.

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