Introduction The purpose to this study was to compare the clinicopathologic characteristics and prognosis of patients with serous stage I borderline ovarian tumors (BOTs) to patients with mucinous stage I BOTs.

Methods This was a retrospective cohort series of patients with stage I BOTs diagnosed and treated between 1995 and 2009 at a single institution. The records were analyzed for patients’ clinicopathologic information. The recurrence rates were compared using the Kaplan-Meier method.

Results During the study period, 198 patients (73.6%) with mucinous BOTs and 71 patients (26.4%) with serous BOTs were identified. Patients with serous tumors tended to be asymptomatic (53.5%) and frequently had elevated CA-125 levels and positive results from peritoneal cytology. Conversely, mucinous tumors were more related to the presence of symptoms (70.7%), elevated CA-19-9 levels, and pseudomyxoma and were larger tumors with a mean size of 15.6 cm. After a median follow-up of 56.5 months, 15 patients had developed 16 recurrences. Among these, 14 borderline recurrences developed in 6 patients with mucinous tumors and in 7 patients with serous tumors, and 2 invasive recurrences developed in only patients with mucinous tumors. No difference in recurrence rate between mucinous and serous tumors was observed. In addition, no disease-related death occurred.

Conclusions Our study found that, although distinct differences in clinical and pathologic characteristics between stage I mucinous and serous BOTs are seen, result from tumor histology was not associated with disease prognosis.