Last year, Grail reported that 44.6% of patients with positive test results on Galleri actually had cancer. Galleri is a multi-cancer early detection test. However, in the latest analysis, the figure, known as the positive predictive value, has fallen to 38.0%. This suggests that the diagnostic blood test is less accurate than previously reported.
This decrease in Positive Predictive Value (PPV) estimate means that a higher proportion of people underwent follow-up procedures despite being cancer free. Most of the false positives were caught and subsequently diagnosed correctly after diagnostic imaging, which was used on 93.0% of the patients. But 29.8% of the participants with false alarms underwent invasive procedures.
You read that right – almost 30% of patients underwent INVASIVE procedures after being told they had cancer with Galleri to then be told that they did not have cancer…
The older version of the test is not what is currently available for patients. “Grail saw 25 true positives and 33 false positives using the newer test, resulting in a positive predictive value of 43.1%. While an improvement on the results from the early version, the predictive value is still lower than that reported on the older diagnostic last summer. The old test was better at predicting the origin of the cancer, achieving a 97.1% success rate compared to 88.0% for its successor.”
Grail’s Galleri test is a multi-cancer early detection blood test that is marketed as being able to detect cancer signaling across more than 50 types of cancer. As discussed in a previous post, Galleri is a LDT – Laboratory Developed Test – that has no regulation on accuracy from the FDA. There is currently no insurance coverage and patients are paying almost $1000 out of pocket.
With little to no regulation on the accuracy of hereditary cancer genetic tests, as they are all Laboratory Developed Tests (LDTs) without FDA oversight, Center For Genomic Interpretation is here to help you ensure your chosen lab is delivering accurate results for your patients. Follow CGI on LinkedIn and visit our website https://www.genomicinterpretation.org/elevategenetics/ to learn more!
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