The life and times of low-grade serous carcinoma of the ovary.

For the past several years, all women with epithelial ovarian cancer have been treated identically, whether in a clinical trial or off protocol. Over the past decade, we have come to appreciate the magnitude of the heterogeneity of ovarian cancer. The development of the binary grading system for serous carcinoma was a major advance, leading to separate clinical trials for patients with this subtype, originating from the Gynecologic Oncology Group's Rare Tumor Committee. The mitogen-activated protein kinase (MAPK) pathway appears to play a prominent role in the pathogenesis of this subtype. Approximately 20% to 40% of low-grade serous carcinomas have a KRAS mutation, while BRAF mutations are rare-approximately 5%. In genomic profiling studies, these tumors appear to cluster with serous tumors of low malignant potential. Compared with high-grade serous carcinomas, low-grade serous carcinomas are also characterized by a low frequency of p53 mutations, greater expression of ER and PR, and greater expression of PAX2 and IGF-1. Primary treatment of low-grade serous carcinoma includes surgery plus platinum-based chemotherapy (either adjuvant or neoadjuvant). Clinical behavior is characterized by young age at diagnosis, relative chemoresistance, and prolonged overall survival. Current options for treatment of relapsed disease include secondary cytoreduction in selected patients, salvage chemotherapy, or hormone therapy. A recently completed trial of a MEK inhibitor for women with recurrent disease demonstrated promising activity. Future directions will include further investigations of the molecular biology and biomarker-driven clinical trials with targeted agent monotherapy and combinations.