Prenatal Testing Can Detect Cancer in Mothers

A new study suggests that noninvasive prenatal testing (NIPT) for genetic anomalies could identify occult, previously undiagnosed maternal malignancies.

Researchers at Tufts University Medical Center (Boston, MA, USA), the Dana-Farber Cancer Institute (Boston, MA, USA), and other institutions analyzed 125,426 samples submitted between February 15, 2012, and September 30, 2014, from asymptomatic pregnant women who underwent NIPT screening for fetal aneuploidy (chromosomes 13, 18, 21, X, and Y). Abnormal results were detected in 3,757 (3%) of samples; these were reported to the ordering physician with recommendations for further evaluation.

The results showed that from the set of 3,757 aneuploidy samples, 10 cases of maternal cancer were identified. Detailed clinical and sequencing data were obtained in eight of the women. The researchers found that maternal cancers most frequently occurred when an NIPT finding of more than one aneuploidy was detected. All eight cases that underwent further bioinformatics analysis showed unique patterns of nonspecific copy-number gains and losses across multiple chromosomes. In one case, blood was sampled after completion of treatment for colorectal cancer and the abnormal pattern was no longer evident. The study was published on July 14, 2015, in JAMA.

“If someone has cancer, the tumor itself is shedding DNA in the mother's blood. The test is picking up excess amounts of DNA from particular chromosomes. It's kind of an accident in a way that the test is picking up the DNA from the tumor,” said lead author medical geneticist Diana Bianchi, MD, executive director of the Mother Infant Research Institute at Tufts Medical Center. “The take-home message is that women should be aware of this possibility when they seek testing. It doesn't necessarily mean anything is wrong with the fetus.”

NIPT is a screening test that analyzes the mother's blood and contains fragments of both placental and maternal DNA. Certain fetal abnormalities are associated with specific chromosomes and may indicate birth defects or a condition such as Down's syndrome. NIPT can be done as early as the 10th week of pregnancy, and is typically offered to women with high-risk pregnancies, such as older mothers or those with a family history of certain birth defects.

Related Links:
Tufts University Medical Center
Dana-Farber Cancer Institute