Prenatal Testing Incidentally Finds Cancer in Mothers, Becomes Focus of New National Institutes of Health Long-term Study
Discovery could lead to new clinical laboratory testing for cancer screening in new mothers
Any clinical laboratory test that returns unexpected results is worth looking into more deeply. Such was the case with a recent study conducted by the National Institutes of Health (NIH), which investigated cases of pregnant women who received “unusual” results to prenatal lab tests conducted at a dozen labs in North America.
Following cancer screening protocols that included rapid whole-body magnetic resonance imaging, NIH scientists discovered “previously undetected cancers in 48.6% of pregnant people who had abnormal results for prenatal cell-free DNA (cfDNA) testing used to screen for chromosomal disorders in the fetus,” according to an NIH news release.
“They looked like healthy young women, and they reported themselves as being healthy,” Diana Bianchi, MD, head of the Prenatal Genomics and Therapy Section for the Medical Genetics Branch at the NIH’s National Human Genetics Research Institute, and senior author of the government study, told the Associated Press (AP).
While cfDNA tests are not diagnostic, pathologists and clinical laboratory managers involved in genetic testing are likely familiar with them. The blood tests are used by expectant mothers to assess risk of a fetus with an abnormal number of chromosomes that could suggest disorders such as Down Syndrome, according to ARUP Laboratories.
Unexpected results from tests draw attention. This one seems to have a chance to get more traction with labs because the results point to a prenatal test having some success predicting cancer, even if incidentally.
The researchers published their findings in the New England Journal of Medicine (NEJM) titled, “Prenatal cfDNA Sequencing and Incidental Detection of Maternal Cancer.”
“[The study participants] and their care providers need to take the results seriously and have additional testing because in that population there is a 48% risk of cancer,” Diana Bianchi, MD, senior author of the NIH study, told the AP. (Photo copyright: National Institutes of Health.)
Cancer Found in about Half of Those with Abnormal cfDNA
The NIH researchers started a long-term study, called IDENTIFY, to learn more about abnormal cfDNA results that could suggest cancer. Study participants must be:
- Pregnant or postpartum with no known cancer.
- Recipients of “unusual clinical cfDNA-sequencing results or results that are non-reportable (fetal aneuploidy status could not be assessed) from one of 12 different commercial laboratories,” they wrote in NEJM.
For the study’s initial cohort of 107 participants, researchers repeated cfDNA sequencing testing and coordinated standard medical diagnostic tests (such as Pap smears) and whole-body magnetic resonance imaging.
As reported by Ars Technica:
- 52 women (48.6%) were found to have “hidden cancers.”
- 32 had blood cancers.
- 20 had solid tumors in the breast, bile duct, colon, pancreas, lung, kidney, bone, and adrenal gland.
- 13 of the 20 with solid tumors were able to access “potentially curative treatments.”
- 55 women did not have cancer and may have obtained an unreliable cfDNA result.
“In this study, 48.6% of participants who received unusual or nonreportable clinical cfDNA-sequencing results had an occult cancer (cancer of unknown primary).
“Further study of DNA-sequencing patterns that are suggestive of occult cancer during prenatal screening is warranted,” the researchers wrote in NEJM.
Follow-Up Testing Needed
Cancers found in the study participants “included colorectal, breast, lung and pancreatic cancers, as well as lymphoma, cholangiocarcinoma and renal carcinoma. The screening test analyzes placental DNA fragments circulating in the maternal bloodstream to identify an extra chromosome or to determine the baby’s sex,” according to the NIH news release.
Bianchi told AP the study results also pointed to a “very chaotic” pattern in DNA-sequencing of women with cancer, and that more research is needed to find out who should be screened for cancer.
Clinical laboratories and pathologists who analyze cfDNA tests could take a leadership role in assessing current standards for the tests, determining how suspicious results are reported, and suggesting needed changes.
—Donna Marie Pocius
