Blood test for cancer? Maybe

Dr. Diana Bianchi

CANCER DIGEST – July 13, 2015 – Genetic tests for abnormal chromosomes associated with Downs syndrome and other defects in the fetus, may also detect underlying conditions in the mother, including cancer according to a new study. 

The study reports on the accidental findings from a case series of eight women who had abnormal noninvasive prenatal testing results. While their fetuses had normal chromosomes, later genetic analysis showed that the abnormal findings were due to a variety of undiagnosed cancers in the mothers.

The team of scientists and clinicians, led by Diana W. Bianchi, MD, executive director of the Mother Infant Research Institute at Tufts Medical Center, reported the results of their DNA sequencing analysis today in the Journal of the American Medical Association.

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 analyzes fragments of placental and maternal DNA that circulate in the mother’s blood. In women with cancer, the blood sample also contains cancer DNA.

The cases in this study came from a larger group of 125,426 samples submitted from pregnant women who underwent noninvasive prenatal testing for fetal chromosomal abnormalities between 2012 and 2014. In the women that became this study their physicians later reported 10 cases of cancer to the laboratory that originally conducted the noninvasive prenatal testing.

Dr. Bianchi’s group analyzed eight of the 10 cases in depth and found that 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 prenatal testing, suggesting that the pattern of abnormalities found may indicate cancer. 

“The take-home message is that women should be aware of this possibility when they seek testing,” said Dr. Bianchi in a press release. “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.”

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