Hereditary Cancer Gene Panel Testing in a Croatian Cohort: The First Results from the University Hospital of Split

Background and Objectives: Hereditary cancer predisposition is associated with pathogenic germline variants in numerous genes. Identification of inherited cancer susceptibility enables personalized screening, preventive interventions, and targeted therapies. It also facilitates cascade testing of relatives who may be at increased risk and benefit from tailored clinical management. We describe the first results of hereditary cancer patient identification, selection, and genetic testing at the University Hospital of Split. Materials and Methods: Next-generation sequencing and hereditary cancer gene panel analysis were performed in individuals who met the National Comprehensive Cancer Network clinical criteria for genetic testing at the University Hospital of Split between May 2025 and July 2026. A comprehensive cancer gene panel covering 101 genes was used. Results: A total of 297 individuals underwent genetic testing, including 268 (90.24%) females and 29 (9.76%) males. Of these, 138 (46.46%) were unaffected individuals who met testing criteria based on a family history of cancer. Among individuals with a personal history of malignancy, breast cancer was the most common diagnosis, occurring in 130 patients (43.77%). Pathogenic or likely pathogenic (P/LP) variants, as well as risk variants, were identified in 80 individuals (26.94%), including seven individuals carrying two P/LP variants. Variants were detected in 29 different genes, most frequently BRCA1 (n = 14), BRCA2 (n = 11), CHEK2 (n = 9) and PALB2 (n = 7). The detected variant types included frameshift (n = 30), missense (n = 22), nonsense (n = 21), splice-site variants (n = 4), start loss variants (n = 4), large deletions (n = 4), and in-frame deletions (n = 2). Conclusions: To our knowledge, this is the first study to report the results of panel germline testing for hereditary cancer syndromes in a Croatian population. These findings provide initial epidemiological data on the spectrum and distribution of P/LP variants. The relatively high detection rate may reflect the recent implementation of genetic testing and the careful selection of individuals with a strong clinical suspicion of hereditary cancer predisposition.