Introduction
Ovarian cancer is the seventh most common cancer in women and the leading cause of death among gynecological cancers (1) . Its incidence varies considerably between countries. Compared with other countries, China has a relatively low incidence of ∼5/100,000 females, which is about one-fourth the incidence in northern European countries (2) . The lack of screening tests for early detection and limited treatment options for this malignancy means that the survival rate remains disappointingly low. Five-year survival rates are