Can cancer blood tests live up to the promise of saving lives?

Joyce Ares had just turned 74 and was feeling well when she agreed to give a blood sample for research. So when the symptoms of cancer came positive in the screening test, she was surprised.

After repeated blood tests, PET scans and needle biopsy, she was diagnosed with Hodgkin lymphoma.

“I cried,” said the retired real estate broker. “Just a couple of tears and thought, ‘Okay, what do we do now?'”

A Canby, Oregon, resident volunteered to take a blood test that is being billed as a new frontier in cancer screening for healthy people. It looks for cancer by examining the DNA fragments shed by tumor cells.

Such blood tests, called liquid biopsies, are already used in patients with cancer to treat them and to see if tumors come back.

Now, one company is promoting its blood test to people with symptoms of cancer as a way to detect tumors in the pancreas, ovaries and other sites where there is no recommended screening method.

It’s an open question whether such cancer blood tests — if added to routine care — can improve the health of Americans or meet the White House’s goal of halving cancer mortality in the next 25 years. can help.

With advances in DNA sequencing and data science making blood tests possible, California-based Grail and other companies are rushing to commercialize them.

And US government researchers are planning a larger experiment — possibly up to seven years and with 200,000 participants — to see if the blood test can live up to the promise of catching more cancers earlier and saving lives.

“They look amazing, but we don’t have enough information,” said Dr. Lori Minassian of the National Cancer Institute, who is involved in planning the research. “We don’t have definitive data that shows they will reduce the risk of dying from cancer.”

Grill is well ahead of other companies, with 2,000 doctors ready to test for $949. Most insurance plans do not cover the cost. The tests are being marketed without the endorsement of medical groups or the recommendation of US health officials. This type of test does not require review by the Food and Drug Administration.

“For a drug, the FDA demands that there is a fairly high probability that not only is the benefit proven, but that they outweigh the harm. This is not the case with devices such as blood tests,” says the Lisa Schwartz Foundation for Truth in Medicine’s Dr. Barry Kramer said.

Grill plans to seek approval from the FDA, but is marketing its test as it submits data to the agency.

The history of cancer screening has taught caution. In 2004, Japan stopped mass screening of infants for childhood cancer after studies found it did not save lives. Last year, a 16-year study of 200,000 women in the United Kingdom found that routine screening for ovarian cancer made no difference in deaths.

Cases like these have uncovered some surprises: Screening finds some cancers that don’t need to be cured. the other side? Many dangerous cancers grow so fast that they escape screening and prove fatal anyway.

And screening can do more harm than good. Concern over false positives. unnecessary expenses. And serious side effects from cancer care: PSA testing for men can lead to treatment complications like incontinence or impotence, even when some slow-growing prostate cancer may never have caused trouble.

The evidence is strongest for screening tests for cancers of the breast, cervix and colon. For some smokers, lung cancer screening is recommended.

Recommended tests — mammography, PAP tests, colonoscopy — look for cancer one at a time. New blood tests look for multiple cancers at once. That’s an advantage, according to Grill executive Dr. Joshua Offerman.

“We do four or five cancer screenings in this country, but (many) cancer deaths are coming from cancers that we’re not looking for at all,” Offman said.

Dr. Tomas Beer of Oregon Health & Science University in Portland led the company-sponsored study that Joyce Ares joined in 2020. After a miserable winter of chemotherapy and radiation, doctors told him the treatment was successful.

“Her case is not an outlier, but it’s like expecting the ideal outcome, and not everyone has that,” Beer said.

While other early cancers were found in study participants, some had less obvious experiences. For some people, blood tests have led to scans that never detect cancer, which may mean that the result was a false positive, or it may mean that there is some mysterious cancer that will show up later. For others, blood tests detected cancer that turned out to be advanced and aggressive, Beer said. An older participant with a worse case refused treatment.

Grail continues to update its testing as it learns from these studies, and is sponsoring a trial with Britain’s National Health Service in 140,000 people to see if the blood test can detect cancers caught in late stages. can reduce the number.

Although Ares feels lucky, it’s impossible to know whether his test added healthy years to his life or made any real difference, said Kramer, former director of the National Cancer Institute’s Division of Cancer Prevention.

When told of his experience, Kramer said, “I sincerely hope that Joyce has benefited from this trial.” “But unfortunately, we can’t know at the individual Joyce level whether that’s the case.”

Cancer treatments can have long-term side effects, he said, “and we don’t know how fast the tumor will grow.” Treatment for Hodgkin lymphoma is so effective that delaying treatment until symptoms are felt can produce the same happy outcome.

For now, health experts emphasize that the Grail blood test is not a diagnosis of cancer; A positive result triggers further scans and biopsy.

“This is a path in clinical testing that has never been tried before,” Kramer said. “Our final destination is a test that has a clear net benefit. If we don’t do it carefully, we’ll be out of the way.”


The Associated Press Department of Health and Science receives support from the Howard Hughes Medical Institute’s Department of Science Education. AP is solely responsible for all content.

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