What is the impact of stromal microinvasion on oncologic outcomes in borderline ovarian tumors? A multicenter case-control study

To investigate clinicopathological characteristics and oncological outcome of women with microinvasive BOTs. A retrospective multicenter case–control study was conducted on 902 patients with BOT, who underwent surgery from January 2002 to December 2015 at six participating gynecologic oncology centers from Turkey. Among 902 patients, 69 had microinvasive BOT. For every patient with microinvasive BOT, two controls were randomly selected from another database based on decade of age and stage of disease at diagnosis. The clinical–pathological characteristics and oncological outcomes were compared between BOT patients with and without stromal microinvasion. Risk factors for poor oncological outcomes were investigated in a multivariate analysis model. Overall survival (OS) and disease-free survival (DFS) were estimated using the Kaplan–Meier method. Patients with microinvasive BOT had a significantly higher rate of recurrence than patients without microinvasive BOT (17.4 vs 7.8%, OR 3.55, %95 CI 1.091–11.59, p = 0.03). Stage at diagnosis (stage I versus II/III) and type of surgery (cystectomy versus others) were found as other significant prognostic factors for recurrence in multivariate analysis (OR 8.63, %95 CI 2.48–29.9, p = 0.001 and OR 19.4, %95 CI 3.59–105.6, p = 0.001, respectively). Stromal microinvasion was found as a prognostic factor for significantly shorter DFS (26.7 vs 11.9 months, p = 0.031, log rank). However, there was no significant difference in OS between two groups (p = 0.99, log rank). Stromal microinvasion is significantly associated with decreased DFS. In addition, our study confirms that the risk of recurrence is higher in patients with microinvasive BOT.