The Molecular Landscape of 227 Adult Granulosa Cell Tumors of the Ovary: Insights into the Progression from Primary to Recurrence

Adult granulosa cell tumors (AGCTs) of the ovary are characterized by their propensity for late recurrences and are primarily managed surgically due to the limited efficacy of systemic treatment. The FOXL2 p.C134W somatic mutation has been identified in ∼95% of AGCT cases, and TERT promoter alterations have been linked to worse overall survival. This study highlights the potential prognostic significance of FOXO1 mutations, suggesting that they may be associated with poorer overall survival and shorter time to recurrence. A total of 183 primary AGCTs and 44 recurrences without corresponding primary tumors were analyzed. The primary AGCTs were categorized into 3 groups: 77 nonrecurrent tumors, 18 tumors that later recurred (including 9 cases with matched primary-recurrence pairs), and 88 tumors with unknown recurrence status. Targeted next-generation sequencing was conducted on 786 cancer-related genes to investigate their genetic profile. The study aimed to identify the molecular alterations associated with AGCT pathogenesis and recurrence rate, comparing primary versus recurrent tumors, and primary recurrent versus primary nonrecurrent cases. Our findings confirmed the high prevalence (99%) of the FOXL2 p.C134W mutation in AGCTs. Secondary truncating FOXL2 mutations were observed in 5% of cases. Two cases with typical AGCT morphology were FOXL2 wild-type, harboring mutations in KRAS or KMT2D instead, suggesting alternative genetic pathways. TERT promoter mutations were found in 43% of cases, more frequently in recurrences. Other recurrent mutations detected in the cohort included KMT2D (10%), FOXO1 (7%), CHEK2 (5%), TP53 (3.5%), PIK3CA (3.5%), and AKT1 (3%). Two recurrent, FOXL2-mutated cases also carried DICER1 mutations. One tumor exhibited MSI-high status and a tumor mutation burden of 19 mut/Mb.Our results indicate the need for further investigation into the role of FOXO1 as a potential prognostic marker in AGCTs.