A study, called ‘Prevalence of Variant Reclassification Following Hereditary Cancer Genetic Testing’, has examined how often the results of genetic testing for cancer risk are later reclassified. To read about the study in more detail, you can view it here, at the JAMA Network.
Genetic Testing for Cancer Risk
Cancer isn’t usually inherited, but certain genes can increase a person’s risk of developing some forms of cancer, particularly breast, ovarian, colorectal, and prostate cancers. For example, particular variants of the BRCA1 and BRCA2 genes are known to increase the chance that a woman will develop breast or ovarian cancer. There are tests for variants that can be used to help people learn more about their risk of cancer and the results may classify variants depending on their severity. To learn more about genetic testing for cancer risk, click here.
Variants linked to cancer may be reviewed and reclassified as new information becomes available. However, according to the paper recently published in JAMA, there is limited research into how common this is. To better understand the impact of variant reclassification, researchers carried out a retrospective study of 1.45 million people, who underwent 1.67 million initial tests between 2006 and 2016 in one laboratory. The genetic variants were classified as (1) benign, (2) likely benign, (3) of uncertain significance, (4) likely pathogenic, or (5) pathogenic.
Of the 1.67 million tests carried out, 6.4% of unique variants were later reclassified. Only a small number of these changes affected variants initially labeled as benign, likely benign, or likely pathogenic, or pathogenic. A much larger proportion (7.7%) of unique variants originally described as of uncertain significance were later reclassified. Of these, over 90% were downgraded to likely benign or benign status, while 8.7% were upgraded to likely pathogenic or pathogenic.
The reclassification of variants has a huge impact on people’s lives, their choices, and ability to plan for the future. Although more research is still needed to confirm these results, this study highlights how the information that doctors have, and patients receive, can change over time – particularly in the fast-paced area of genetics.