A common DNA test can find cancer in bodies of seemingly healthy pregnant people : Shots - Health News Testing pregnant people's blood to look at free-floating DNA can tell doctors about the health of the fetus. But these tests sometime turn up DNA that might be shed by cancerous cells.

A new kind of blood test can screen for many cancers — as some pregnant people learn

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Screening tests like mammograms and colonoscopies can catch certain cancers early. But for most deadly cancers, there are no screening tests. Research is underway to develop a simple blood test that could screen for multiple kinds of cancer at once. As NPR's Nell Greenfieldboyce reports, some people are already getting this kind of cancer screening by accident.

NELL GREENFIELDBOYCE, BYLINE: When Kathleen Aukstikalnis was expecting her first child, she got a prenatal test that's become pretty routine. The test takes a sample of a pregnant person's blood, and it looks for bits of free-floating DNA. Some of this DNA is released by cells in the placenta. That means it can be used to screen the pregnancy for chromosomal abnormalities like Down's syndrome. It can also reveal the baby's sex. Aukstikalnis says all her friends who had babies had gotten this test.

KATHLEEN AUKSTIKALNIS: They're like, oh, it's so exciting. You're going to find out, you know, all these different things from it.

GREENFIELDBOYCE: The first time she took the test, a nurse called back later and said there had been some error. The results were inconclusive. So she got her blood drawn again. And again, the results came back inconclusive. Her nurse midwife said, I don't know what this means.

AUKSTIKALNIS: So she just said, like, this is a result that's extremely rare and that I was the first example of someone in their practice having ever had this case.

GREENFIELDBOYCE: The nurse midwife suggested that Aukstikalnis and her husband speak to a genetic counselor. At that point, she says...

AUKSTIKALNIS: I was more worried about the baby. I wasn't thinking anything about myself really at all.

GREENFIELDBOYCE: But the counselor explained that the free-floating DNA is actually a mixture. Some reflects the genetic makeup of the fetus. But even more of that DNA comes from the pregnant person's own cells. And if some of those cells are cancerous, that can actually mess with the results of this test.

AUKSTIKALNIS: So that was, like, really difficult to wrap my head around. I wasn't expecting to hear anything about myself.

GREENFIELDBOYCE: Actually, though, there's a huge amount of research going on right now on using cell-free DNA to screen the blood for multiple kinds of cancer at once. President Biden's Cancer Moonshot has made the development of this kind of cancer screening a priority, as he noted in a recent speech.


PRESIDENT JOE BIDEN: Imagine simple blood test during an annual physical that could detect cancer early, where the chances to cure are best.

GREENFIELDBOYCE: That's the goal. But even though some of these tests do seem technically good at detecting DNA from cancerous cells, there's no definitive evidence yet that this information can be used to benefit people's health.

LORI MINASIAN: We don't know, in fact, that they truly will pick up those cancers in a time frame where when you intervene, when you do something after that test to that patient, it makes a difference.

GREENFIELDBOYCE: That's Lori Minasian, deputy director for cancer prevention at the National Cancer Institute. Her agency is currently organizing a huge clinical trial for multicancer detection tests that will enroll 24,000 people and eventually may expand to over 200,000 to see if using them to screen can truly help.

MINASIAN: There's so much we don't know about this. We need to do the trials so we can get the information.

GREENFIELDBOYCE: In the meantime, it just wasn't clear what Aukstikalnis should do. Her counselor told her that there was one small clinical trial for pregnant folks like her whose inconclusive test results might mean a cancer somewhere in the body was releasing DNA into the blood. One of the people who started this study is Diana Bianchi. She's head of the National Institute of Child Health and Human Development.

DIANA BIANCHI: We want to be able to tell them what to do with these results - both the health care providers and the patients.

GREENFIELDBOYCE: Her plan was to bring pregnant people to the clinical center at the National Institutes of Health, give them free full-body MRI scans and an exhaustive blood workup.

BIANCHI: Everyone thought we were a little crazy at the beginning, that it's going to be so hard to recruit people. And there's no way these healthy women are going to have cancer.

GREENFIELDBOYCE: Because keep in mind, the people in this study got the testing not to be screened for cancer but because they were intending to learn about a pregnancy. So they're all fairly young and seemingly healthy. Amy Turriff is a genetic counselor at NIH.

AMY TURRIFF: I think to the average person, if you have cancer, you don't feel well. You have some lump, bump, some sort of scary symptom. And that's just not the experience of the people who are being referred to us.

GREENFIELDBOYCE: She says that's why in the end, they often choose not to participate in the study. Bianchi says those that do often end up getting troubling news.

BIANCHI: Over half of them do have a tumor. So this is not a trivial finding. This really needs to be taken seriously.

GREENFIELDBOYCE: She says all kinds of cancers have been detected - rectal cancer, rare, once-in-a-million tumors. Aukstikalnis decided to go to the NIH Clinical Center with her husband, but she didn't really think anything was wrong.

AUKSTIKALNIS: There could be some sort of, like, weird thing that pops up on there that's benign that just happens to, like, trigger this type of result. Like, you just - there were other things that it could be.

GREENFIELDBOYCE: She let them draw numerous vials of blood. She spent over an hour in an MRI machine. At the end of the day, a team of doctors sat her down and said she had masses in her neck and chest that looked like lymphoma.

AUKSTIKALNIS: I was like, lymphoma? Like, what's lymphoma? Hearing that news that you have cancer is just, like - it's hard to describe. It's just such, like, an overwhelming experience.

GREENFIELDBOYCE: Especially because she was pregnant.

AUKSTIKALNIS: Your emotions are kind of all over the place. And it was, like, definitely really difficult in the time.

GREENFIELDBOYCE: She underwent chemotherapy while pregnant, something that can be done safely. And she eventually had a healthy baby girl. Since then, she's needed more treatment, including a stem cell transplant that required her to be in the hospital for almost a month this fall. Now she's just happy to be home with her family.

AUKSTIKALNIS: I'm also, like, incredibly grateful that I found out when I did and then found out, like, I could get treatment at an early stage and that it was safe during pregnancy.

GREENFIELDBOYCE: She hopes participating in that study and talking about all this will help other people understand their options when a test result unexpectedly raises the possibility of cancer.

Nell Greenfieldboyce, NPR News.


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