1/4 of hereditary cancer genetic testing reports were reclassified during ten years

Single genetic testing laboratory would need to reclassify 1 in every 4 reports throughout the past decade, as a consequence of changes in variant interpretations.

Detection of variants in the genome is the first step – the second, no less important step, is variant interpretation. Mutations are assessed by research. Those valuations change over time, as changes technology, available genome databases, and basic biological knowledge.

Past decade genomic sequencing procedures in one laboratory, involving 1,45 million individuals (56,6% who had cancer), were reviewed to evaluate the volatility of genetic interpretation. It was found that 0,9% variants were reclassified between different categories (for example: from pathological to uncertain) and 7,7% variants were reclassified in the same category (for example: from benign to likely benign). However, as many variants were in each report, total changes affect 24,9% of genetic reports.

Some of the most significant changes included specific variants in BRCA1, TP53 and BRIP1 which were reported as pathogenic but nowadays there are not explicitly associated with cancer.

The study highlights that time between performing a report and change to a variant was 1,1 year over the past decade. In the context of cancer patients, a moment of an update is close to life expectancy in most cancer diseases. Nevertheless, last years brought shortening of time needed to send a new report with corrected interpretation – down to 4-5 months.

More: “Prevalence of Variant Reclassification Following Hereditary Cancer Genetic Testing”, J. Mersch et al., 2018, doi:10.1001/jama.2018.13152.