Introduction/Background*The aim of this study was to assess prognostic factors and implications on further management in a large series of stage-II or III Serous Borderline Ovarian Tumors (SBOTs) with a long-term follow-up.

Methodology Patients with SBOTs and peritoneal implants treated in, or referred to, our institution were retrospectively reviewed. Prognostic factors on invasive recurrence, disease-free (DFS) and overall survival (OS) were analyzed.

Result(s)*Between 1971 and 2017, 212 patients were identified and followed (33 having invasive implants). After a median follow-up of 115 months, 70 recurrences were observed, 28 of them under the form of invasive disease. DFS at 5 years and 10 years was 73% and 62% respectively. The use of a conservative treatment (HR=5.5[3.33-9.08], p<.0001), the presence of ≥ 3 peritoneal sites with implants (HR=1.65[1.01-2.72], p=.045) were unfavorable prognostic factors for DFS. The presence of ≥ 3 peritoneal sites with implants (HR=3.02[0.96-9.53], p=.049) and the presence of stromal microinvasion (HR=3.19[1.12-9.1], p=.022) were unfavorable prognostic factors for OS. Non-conservative surgery (HR=7[2.35-20.87], p=0.0002), invasive implants (HR=5.37[1.29-22.26], p=0.013), and ≥ 3 peritoneal sites with implants (HR=3.56 [1.11-11.39], p=0.024) were identified as predictors of recurrence in the form of an invasive disease. Invasive implants were not associated with DFS (HR=1.39[0.77-2.51], p=0.27), nor OS (HR=1.76[0.57-5.47], p=0.32).

Conclusion*After a long-term follow-up, type of peritoneal implants is no longer a prognostic factor for OS. Implants ≥ 3 peritoneal sites seem to impact significantly OS and then require a specific follow-up in this subgroup of patients.