Non-invasive prenatal testing is method used to screen for Down’s syndrome and other conditions caused by genetic abnormalities in a developing fetus. However, a new study finds there may be another use for the test- detecting early-stage maternal cancers.
NIPT looks at DNA from the fetus in the mother’s blood. As such, it doesn’t have the risk of miscarriage associated with invasive testing methods.
According to Nathalie Brison, PhD, a senior scientist in the Clinical Cytogenetics laboratory at the Centre for Human Genetics, UZ Leuven, the research team had initially wanted to increase the accuracy of the NIPT test in order to break through some of the technical problems that cause it to result in false negative or false positive results when screening for chromosomal disorders in the foetus.
Common Chromosomal Abnormality
Down’s, or trisomy 21, is the most common chromosomal abnormality, occuring in about one in 700 babies. Risks of giving birth to a baby with Down’s rises with the age of the mother, and goes sharply higher from the age of 36 years.
“We therefore felt it important that we improved the accuracy of the test,” Dr Brison says. ”Even though it is very reliable, we believed that we could make it even better, and in doing so we could also find other chromosomal abnormalities apart from the traditional trisomy syndromes – Down’s, Edward’s (trisomy 18), and Patau (trisomy 13). Using the new, adapted test in over 6000 pregnancies, and looking at other chromosomes, we identified three different genomic abnormalities in three women that could not be linked to either the maternal or foetal genomic profile. We realised that the abnormalities bore a resemblance to those found in cancer, and referred the women to the oncology unit.”
The presence of three different early stage cancers in the women were revelaled on further examination, using total body MRI scanning and pathological and genetic investigations.
Although this is a proportion in the range to be expected in the normal population, without NIPT these cancers would have been arguably not liekly to have been detected until they became symptomatic, at a much later stage.
“Considering the bad prognosis of some cancers when detected later, and given that we know that it is both possible and safe to treat the disease during pregnancy, this is an important added advantage of NIPT,” comments principal investigator Professor Joris Vermeesch. “During pregnancy, cancer-related symptoms may well be masked; fatigue, nausea, abdominal pain, and vaginal blood loss are easily interpretable as a normal part of being pregnant. NIPT offers an opportunity for the accurate screening of high risk women for cancer, allowing us to overcome the challenge of early diagnosis in pregnant women.”
The results suggest that NIPT might enable the detection of pre-symptomatic cancers not just in pregnant women, but more widely.
“We now know that it is possible to offer the accurate detection of chromosomally imbalanced cancers to the general population via minimally invasive screening methods,” says Dr Brison. “The normalisation of the NIPT profile in these patients following treatment indicates that we can also measure response to treatment as early as after the first administration of chemotherapy. Of course, larger scale studies will be required to validate these results further, but we are confident that we have made an important step towards the possibility of wide-scale, effective, non-invasive cancer screening capable of detecting disease at an early stage.”
Photo: Fiona Yaron-Field, Wellcome Images