Noninvasive prenatal testing may also detect some maternal cancers

(Press-News.org) BOSTON (July 13) - A study published today in the Journal of the American Medical Association shows that genetic test results, as revealed by non-invasive prenatal testing for fetal chromosome abnormalities, may detect underlying conditions in the mother, including cancer. The study reports on a case series of eight women who had abnormal noninvasive prenatal testing results. Their fetuses had normal chromosomes; retrospective genomic analysis showed the results were due to undiagnosed cancers in the mothers.

A team of scientists and clinicians, led by Diana W. Bianchi, MD, Executive Director of the Mother Infant Research Institute at Tufts Medical Center, reports the results of their DNA sequencing analysis in an article titled "Noninvasive Prenatal Testing Incidentally Detects Occult Maternal Malignancies." Their findings demonstrate that previously undetected maternal cancers may provide a biological explanation for some prenatal screening results that differ from results of prenatal diagnostic tests.

Noninvasive prenatal screening is a recent clinical advance that provides pregnant women with information about possible chromosomal abnormalities, such as Down syndrome, in their fetuses. The screening test, which can be offered as early as the tenth week of pregnancy, analyzes fragments of placental and maternal DNA that circulate in the maternal plasma. In women with cancer, the plasma sample also contains cancer DNA.

Diagnosis of cancer during pregnancy is relatively uncommon, with an incidence of about 1 in 1,000 women. Cancer detected during pregnancy most often occurs in the breast, cervix, ovary and colon, as well as melanoma, lymphoma and leukemia. "This study provides one explanation for when noninvasive prenatal testing results are different from the fetal karyotype. It highlights the need to perform a diagnostic procedure to determine true fetal karyotype whenever noninvasive prenatal testing suggests chromosomal abnormalities," said Dr. Bianchi, an international expert on noninvasive prenatal testing.

The cases in this study came from a larger group of 125,426 samples submitted from asymptomatic pregnant women who underwent noninvasive prenatal testing for fetal chromosomal abnormalities between 2012 and 2014. Of these, 3757 cases were positive for one or more abnormalities in the number of chromosomes 13, 18, 21, X or Y. The women's physicians later reported ten cases of cancer to the laboratory that originally conducted the noninvasive prenatal testing. The study analyzed eight of the ten cases in depth. All of the women had abnormal noninvasive prenatal test results, and most frequently, more than one chromosomal abnormality was detected, which is a very unusual result. Cancer was diagnosed during pregnancy or postpartum in these women at an average of 16 weeks following the initial noninvasive prenatal testing.

Some women were tested more than once, and some were tested both during pregnancy and after. One patient had testing after treatment for colorectal cancer, and the abnormal pattern was no longer evident, suggesting a response to treatment. "Noninvasive prenatal testing results may lead to findings of an underlying maternal condition, which, in these cases, was due to cancer," said Dr. Bianchi. "The take-home message is that women should be aware of this possibility when they seek testing. More research needs to be done to further study this occurrence to help guide physicians on how to counsel women and manage their follow-up care."

INFORMATION:

Dr. Bianchi is Founding Executive Director of the Mother Infant Research Institute at Tufts Medical Center; Vice Chair for Pediatric Research at Floating Hospital for Children at Tufts Medical Center; Natalie V. Zucker Professor of Pediatrics, Obstetrics and Gynecology at Tufts University School of Medicine; and a member of the genetics program faculty at the Sackler School of Graduate Biomedical Science at Tufts University. She is a member of the Institute of Medicine, a branch of the National Academies.

Funding for the study was provided by Illumina.

The Journal of the American Medical Association article in its entirety can be found here: http://ow.ly/PyL1o. Accompanying videos and soundbites of Dr. Bianchi discussing the study can be viewed and downloaded here: http://ow.ly/PyK3L.

About Tufts Medical Center and Floating Hospital for Children Tufts Medical Center is an exceptional, not-for-profit, 415-bed academic medical center that is home to both a full-service hospital for adults and Floating Hospital for Children. Conveniently located in downtown Boston, the Medical Center is the principal teaching hospital for Tufts University School of Medicine. Floating Hospital for Children is the full-service children's hospital of Tufts Medical Center and the principal pediatric teaching hospital of Tufts University School of Medicine. Tufts Medical Center is affiliated with the New England Quality Care Alliance, a network of more than 1,800 physicians throughout Eastern Massachusetts. For more information, please visit http://www.tuftsmedicalcenter.org.