Borderline epithelial ovarian tumors are a group of heterogenous tumors arising from the external surface of the ovary that have nuclear atypia and changes in mitotic activity but have a low potential of progressing to malignant tumors.

Borderline epithelial ovarian tumors have an incidence of 1.8-4.8 per 100 000 women each year and are most common in women aged 30-50 years, with a median age at diagnosis of 45 years.

There are several histologic subtypes of borderline epithelial ovarian tumors including serous, mucinous, endometrioid, clear cell, Brenner, and mixed. Serous subtypes are the most common, followed by mucinous subtypes. The remaining subtypes make up only about 3%-4% of all borderline epithelial ovarian tumors. Serous subtypes are the most likely to present bilaterally.

Occasionally, borderline ovarian tumors can be associated with extraovarian (peritoneal) implants, which may or may not be invasive. The presence of these implants is related to the overall prognosis and risk of recurrence.

It is thought that multiparity and breastfeeding are associated with a decreased risk of these tumors, while a history of infertility and in vitro fertilization (IVF) is associated with an increased risk. Conflicting evidence exists regarding oral contraceptive use, but more recent studies suggest a protective effect.

A majority of borderline epithelial ovarian tumors are stage 1 at diagnosis and have an excellent prognosis, with a 10-year survival rate of 98% for stage 1 tumors. The recurrence rate for all stages of borderline ovarian tumors is approximately 11%, with about 70% representing recurrent borderline tumors and approximately 30% representing malignant carcinomas.

Related topic: benign epithelial ovarian tumor