Friday, June 12, 2015

Noninvasive Prenatal Tests detect cancer at a very low rate

Noninvasive Prenatal Tests (NIPT) has enjoyed a surge in growth due to their reliance on a simple blood draw to be able to detect fetal chromosomal anomalies, and is one of many tests available during pregnancy.  Over 800,000 women in the US alone had a NIPT last year, according to Eric Topol at the Scripps Translational Science Institute when interviewed by BuzzFeed.

The neat thing reported at the Future of Genomic Medicine conference back in March was that NIPT tests detected 26 cancers in pregnant women, presumably out of the 400,000 MaterniT21 tests that were described at the time, for an overall rate of about 0.01%.  It's impossible to figure what this number should be without looking into Sequenom's data further, but I think it's safe to say that this is way into the range of being incidental. 

However, another new report has just come out of JAMA Oncology, showing that NIPT is able to catch early pre-symptomatic cancers in pregnant women, at a considerably higher rate that is still only about 0.1% (3 in about 4000, according to the paper).

The neat thing about JAMA's study is that they look at whole genome sequencing instead of what Sequenom's MaterniT21 test does, which is to only look for chromosomal count changes in a handful of chromosomes.  The actual paper shows MRIs from these three women, as well as genome wide representation plots (basically, plots of DNA copy numbers) of cells from each patient, which are quite obviously abnormal to anyone working in the cancer genomics field.

What does this mean for those electing for NIPT tests?  You probably don't need to worry about a surprise cancer diagnosis, but that non-invasive genetic tests can be easily adapted (or reinterpreted) for new purposes as time goes on.