The continuum of serous ovarian tumors of low malignant potential and low-grade serous carcinoma of the ovary

Serous tumors of low malignant potential (LMP) and low-grade serous carcinomas appear to exist on a continuum. Factors that increase the risk of relapse of serous tumors of LMP include stage (presence of peritoneal implants), type of peritoneal implant (noninvasive or invasive), and the micropapillary pattern. Of serous tumors of LMP that recur, approximately 80% do so as low-grade serous carcinoma. Low-grade serous carcinoma may also occur de novo, most commonly as stage II, III, or IV. Treatment of low-grade serous carcinoma in either case consists of surgical cytoreduction followed by taxane/platinum chemotherapy. However, clinical studies have indicated that this tumor type is relatively chemoresistant in the primary, neoadjuvant, and recurrent settings. Molecular and expression profiling studies have identified the MAP kinase pathway as prominent in the pathogenesis of low-grade serous carcinoma. In 2005, the Gynecologic Oncology Group established the Rare Tumor Committee, and in 2007, the first of a series of separate clinical trials for low-grade serous carcinoma, studying an MEK inhibitor for recurrent low-grade serous carcinoma, was activated.