Objectives Borderline ovarian tumors are defined as non-invasive epithelial ovarian tumors which can have an intraperitoneal extension. Molecular studies have shown a correlation between the patient‘s response to chemotherapeutic treatments adjunct to surgery and the tumor’s genetic profile, especially related to the KRASand BRAF genes. This study aims to assess the molecular profile of BOTs in the Lebanese population by Whole Exome Sequencing (WES) and correlate the results with patients‘ clinical profiles.

Methods 33 tumors belonging to 32 Lebanese patients presenting with BOTs, diagnosed at Hôtel Dieu de France were included. A total of 234 genes involved in different germinal and somatic types of cancer were analyzed using Next Generation Sequencing in the 33 included tumors. Genetic variants detected in more than 5% of the reads, with a sequencing depth ≥ 50x, were selected.

Results Among 33 tumors, 18 were serous, 12 mucinous and 3 seromucinous. Molecular analysis of tumors allowed us to detect mutations in genes involved in the MAP Kinase (MAPK) cascade and in the DNA repair mechanism. Our initial analysis revealed an association between defects in DNA Double-Strand Break repair and occurrence of mucinous BOT, in 75% of cases. Mutations affecting MAPK signaling pathway were detected in 46.9% of BOT.

Conclusions Here we report the molecular profile of BOT in the Lebanese population. This is the first study associating the DNA repair pathway to BOT. The inclusion of further patients is essential to validate our hypothesis and to better delineate the mechanisms of the disease, thus allowing the implementation of targeted therapeutic approaches.