KRAS mutation in primary ovarian serous borderline tumors correlates with tumor recurrence.

Oncogenic activation of the mitogen-activated protein kinase (MAPK) pathway due to KRAS or BRAF gain-of-function mutation is frequently found in ovarian serous borderline tumor (SBT) and their extraovarian implants. We investigated mutational status of KRAS and BRAF of the primary ovarian SBTs that had a high stage presentation in correlation with clinical outcome. Among 39 consecutive primary SBTs with either invasive implants (20 cases) or non-invasive implants (19 cases), KRAS and BRAF mutational analysis was informative in 34 cases. Sixteen cases (47%) harbored a KRAS mutation, while 5 cases (15%) had a BRAF V600E mutation. High-stage disease (IIIC) was seen in 31% (5/16) of patients with a KRAS mutation and 39% (7/18) of patients without a KRAS mutation (p = 0.64). KRAS mutations were present in 9/16 (56%) tumors with invasive implants/LGSC versus 7/18 (39%) tumors with non-invasive implants (p = 0.31). BRAF mutation was seen in 5 cases with non-invasive implants. Tumor recurrence was seen in 31% (5/16) of patients with a KRAS mutation, compared to 6% (1/18) of patients without a KRAS mutation (p = 0.04). A KRAS mutation predicted an adverse disease-free survival (31% survival at 160 months) compared to those with wild-type KRAS (94% at 160 months; log-rank test, p = 0.037; HR 4.47). In conclusion, KRAS mutation in primary ovarian SBTs is significantly associated with a worse disease-free survival, independent of the high tumor stage or histological subtypes of extraovarian implant. KRAS mutation testing of primary ovarian SBT may servce as a useful biomarker for tumor recurrence.