Low-grade epithelial ovarian cancer: a number of distinct clinical entities?

Purpose of reviewThe purpose of this study is to summarize the contemporary understanding of low-grade epithelial ovarian cancers.Recent findingsLow-grade serous ovarian cancer is biologically distinct from high-grade serous ovarian cancer. It is associated with a high incidence of K-RAS and B-RAF mutations. Although described as indolent due to median progression-free and overall survivals of 20 and 99 months, respectively, with a median age of diagnosis of 43 years, it accounts for a significant number of patient-years lost. Retrospective studies suggest response rates of 5% for chemotherapy and 9% for antioestrogen therapy. A prospective study of the mitogen-activated protein kinase kinase inhibitor selumetinib (response rate 15%) and retrospective bevacizumab studies suggest that these may be more effective approaches.Limited retrospective clinical data and even more sparse molecular data suggest that similar distinctions may exist between low-grade endometrioid and mucinous ovarian cancers and their respective high-grade counterparts, but more research is required in order to clarify the biological differences and the implications that these have for management.SummaryThe results of phase III mitogen-activated protein kinase kinase inhibitor studies in low-grade serous ovarian cancer and further clinical and biological assessment of low-grade endometrioid and mucinous ovarian cancers are urgently required.