Clinical and genetic analysis of recurrent adult-type granulosa cell tumor of the ovary: Persistent preservation of heterozygous c.402C>G FOXL2 mutation

BACKGROUND: Adult-type granulosa cell tumors of the ovary (aGCTs) are rare tumors that represent 2–5% of ovarian malignancies. The prognosis of this tumor is favorable, and it is characterized by slow progression. 10–30% of these tumors recur after 4–7 years of the primary surgery and the 5-year survival rate from the first recurrence is 55%, for the incompletely resected patients. At this time, complete resection is the only prognostic factor for better outcome, and establishing a novel strategy for identification and/or treatment of recurrent tumors is crucial. After the discovery of heterozygous c.402C>G FOXL2 mutations in 97% of cases of aGCT, much effort has been made to find the role of the mutation on the pathogenesis of aGCT, however, little is known about the role of the mutation in disease progression. METHODS: We analyzed the clinical data of 56 aGCT patients to find a marker of recurrence. In particular, we compared the FOXL2 status in 5 matched primary and recurrent samples by immunohistochemistry, and TaqMan allelic discrimination assay to address the role of FOXL2 in potential mechanisms of recurrence. RESULTS: The clinical data analysis was consistent with complete resection as an indicator of disease eradication, though the sample size was limited. The genetic analysis showed all the samples, including recurrent tumor samples up to 14 years after the primary surgery, expressed heterozygous c.402C>G FOXL2 mutation and the FOXL2 protein expression. CONCLUSION: This report describes the preservation of heterozygous c.402C>G FOXL2 mutation in recurrent aGCTs. This finding adds further credence to the concept that the c.402C>G FOXL2 mutation is oncogenic and integral to this disease.