Secondary findings after multi-gene panel testing in 7,388 patients with suspected cancer predisposition syndrome.

Our study focused on the individuals’ preference for disclosure of secondary findings (SF) in hereditary cancer genes (HCG) and the frequency and type of SF after multi-gene panel testing (MGPT) in individuals with a suspected cancer predisposition syndrome (CPS). SF are defined as pathogenic/likely pathogenic variants (P/LPV) that were not anticipated and without a known correlation to the primary indication for genetic testing. 7,388 individuals with a suspected CPS were tested in a 6-year period 2019–2024. SF in HCG were reported in agreement between clinical and laboratory geneticists. Data about the reported SF and preference to receive SF was acquired from patient medical documentation. Our study showed that majority of patients (98.8%) opted-in for disclosure of SF. We identified 42 SF (0.57% of all tested individuals) in 41 individuals. 11 were found in the HCG from the ACMG list, 28 in HCG not included in ACMG list and 3 were discovered in mosaic form. Our study provides important insight into frequency and type of SF in HCG in a cohort of individuals with suspected CPS. Further studies on larger cohorts are needed to better define the usefulness and potential risks of reporting SF in HCG in individuals without personal/family history of cancer.