Objective The objective of this study was to assess whether there are differences on ultrasound features between epithelial ovarian cancer (EOC) type I and type II.

Methods This was a retrospective study comprising 244 women (mean age, 55.2 years old) with histologically proven EOC treated at our institution over a 12-year period. Clinical (patient age and symptoms and tumor stage), ultrasound (tumor volume, tumor appearance on gray-scale ultrasound, and color score), and histopathologic records were reviewed. Tumors were classified as EOC type I or type II. Type I tumors comprise low-grade serous, low-grade endometrioid, clear cell, mucinous, and transitional cell carcinomas, whereas type II tumors comprise high-grade serous, high-grade endometrioid, malignant mixed mesodermal tumors, and undifferentiated carcinomas. Categorical variables were compared using χ² test. Continuous variables were compared using 1-way analysis of variance with Bonferroni post hoc test or Mann-Whitney U or Kruskal-Wallis test, depending on data distribution.

Results Sixty-seven women (27.5%) had type I EOC, and 177 (72.3%) had type II EOC. We observed that women with type I EOC were younger, presented asymptomatic at diagnosis more frequently, and had lower CA-125 levels and lower tumor stage than women with type II EOC. Type II EOCs were more frequently identified as a solid mass and were smaller lesions than type I EOC.

Conclusions Some differences exist between type I and type II EOC in clinical and ultrasound manifestations. Although the clinical significance of these findings is still to be determined, this information could provide some clues to clinicians faced with the diagnosis of ovarian cancer.