Doubt cast on cancer screening blood test

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I had bilateral breast cancer which was first diagnosed by MRI in 2013 (5 mm, Stage 1). Treated by bilateral mastectomy in 2015. My nonsmoking mother died of lung cancer at age 71. This large cancer probably started when she was younger than I am (age 70).

I will soon get treatment for my severe aortic valve stenosis. It seems like a good idea to make sure I don’t have cancer before investing in heart surgery.

I sent away for a Galleri blood test since this has been hyped to be able to detect 30 different cancers. Then I saw this article today.

Galleri promises to detect multiple cancers—but new evidence casts doubt on this much hyped blood test

A blood test being trialled in large numbers of people in England is facing mounting evidence against its implementation as a screening tool for early cancer.
by * Margaret McCartney, senior lecturer in general practice, freelance writer1, broadcaster and Deborah Cohen
BMJ 2024; 386

…
The NHS is currently running a £150m trial of the test, involving more than 100, 000 participants in England…

The test is one of several multicancer detection blood tests, or “liquid biopsies,” on the market and uses sequencing technology to analyse DNA fragments circulating in the blood, also known as cell free DNA (cfDNA). These cfDNA fragments from cancer cells have specific “methylation patterns.” Grail says that Galleri checks over a million methylation sites in DNA, using machine learning and artificial intelligence to detect whether someone is harbouring a cancer…

But some eight months before the NHS Galleri trial was announced in 2020, Grail published data showing that in patients already known to have cancer the test detected only 43.9% of stage I-III cancers.(https://www.bmj.com/content/386/bmj.q1706#ref-5)

In 2021 another Grail funded study in Annals of Oncology found that the test sensitivity for stage I cancers was only 16.8%…

A 2023 Lancet study suggests that the test’s sensitivity is even lower in a screening population than in previous trial populations. (https://www.bmj.com/content/386/bmj.q1706#ref-11)12 In the Pathfinder study, conducted on asymptomatic patients in North America, 1.4% had a positive test, but 62% of these results turned out to be false positives… [end quote]

The results from the large NHS trial aren’t available yet. The rest of the article discusses the finances and also the important issue of whether early detection using Galleri results in improved mortality.

If I had known of these poor results I would not have ordered the test. I will try to return it since the sensitivity and accuracy are so low that either a positive or negative result would be essentially meaningless.

Wendy

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Yep other thread my 83 y/o friend getting the colonoscopy took the colarector colaguard test and got a positive. Meaningless. He is now risking his colon. He is too old for this procedure.

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My dad is the same age and gets a colonoscopy every year or two (used to be every 6 months, then every year, since he had colon cancer at age 52). What do you mean by “too old for this procedure”?

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False negatives and false positives are a concern in all test methods. Positive results do give you a better chance of finding a cancer early. You get extra attention. Otherwise you might have missed it until too late.

Whether the potential benefit is worth the risk is a personal choice.

Recall that PSAs were discontinued for quite a while due to false positives or positives that were not life threatening. Now PSAs are back and people are getting prostate surgery again.

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Your dad may need to do that because he has had colon cancer.

My friend has not had colon cancer.

The risk is a punctured large intestine and infections thereafter. The wall of the intestine gets thinner with age. In your 80s you can skip getting a colonoscopy if you have no prior history. But that said I do not know the current recommendations.

My friend got through it in good shape. He’s okay. The positive colagard test was a false positive.

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Is Elizabeth Holmes an investor?

Elizabeth Holmes - Wikipedia

intercst

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Medicare doesn’t do the “free” preventive screening colonoscopies after age 75. But if your Primary Care doctor is willing to say he found blood in a prostate exam, you can probably still get a diagnostic colonoscopy with the 20% copay.

intercst

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I always warn people about that. Kaiser kept pushing Colagard when I had them pre-Medicare. I demanded the “free” colonoscopy instead.

Since the positive Colagard test needs to be followed up with a diagnostic colonoscopy (where deductibles and co-pays apply), they were essentially turning my “free” Obamacare colonoscopy into a $5,000 billing opportunity for Kaiser.

You need to stay one step ahead of the Kaiser MBAs. {{ LOL }}

intercst

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Soon there will be college degrees providing the highly specialized knowledge needed to navigate the ever more absurd USA medical billing jungle.

d fb

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Probably not since she may have spent it all on lawyers. So she is probably a marketing consultant or technical advisor.

Mike

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@WendyBG …that was primarily the reason I said that I wouldn’t use these test results in decision making. The maybe/maybe not aspect to cancer detection vs the reality of a definitive diagnosis of a serious cardiac issue. From the outset, the fanfare surrounding this “liquid biopsy” has been largely generated by the company itself, from what I could tell. Oncologists of my acquaintance have been even more scathing.

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Risk benefit analysis WRT false positives (or negatives to a certain extent) is a bit more serious than just a question of individual risk tolerance. False positives have a disadvantages to them as, almost always, they trigger followups. Oftentimes with negative consequences beyond just the financial burden. Not to mention the unnecessary stress.

Of course, that’s a long way from not performing well validated tests and screening (such as advanced lipid testing or simple auscultation) such that patients are, in effect, neglected until significant disease has become established. Like, say, with Wendy and me.

Just sayin’

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