Low Grade Serous Ovarian Carcinoma: From the molecular characterization to the best therapeutic strategy

Low Grade Serous Ovarian Carcinoma, LGSOC, is certainly a rare disease, accounting for only a small proportion of all ovarian carcinomas, nevertheless in the last decade we have acquired many data about its molecular and clinical features and it has been largely accepted that it has distinct pathogenesis, genetic aberrations and clinical behavior compared to High Grade Serous Ovarian Carcinoma, HGSOC, which is the most common ovarian cancer histotype. A large number of series pointed out the high rate of KRAS and BRAF mutations in LGSOCs and Serous Borderline Tumors, SBLTs, in contrast with their rarity in HGSOC. Such finding, together with the recurrent observation of focus of LGSOC associated with areas of SBLT in the same lesion, led to abandon the traditional histology classification, defining three types of serous carcinomas, in favor of a new dualistic grading system which recognizes only LG and HG carcinomas corresponding to distinct tumorigenesis pathways, the former based on KRAS/BRAF mutations and alteration of the MAP/ERK signaling, the latter characterized by early genetic instability and wild type status of KRAS and BRAF. LGSOC shows favorable overall survival, compared to general ovarian cancer population, but worrying resistance to conventional treatments. MEK inhibitors are emerging as active agents and may well represent an effective therapeutic strategy in the near future.