The genomic landscape of low-grade serous ovarian/peritoneal carcinoma and its impact on clinical outcomes

Objective Low-grade serous carcinoma (LGSOC) is a rare epithelial ovarian/peritoneal cancer characterized by younger age at diagnosis, relative chemoresistance, prolonged overall survival (OS), and mutations in the mitogen activated protein kinase (MAPK) pathway compared to high-grade serous carcinoma. We describe the genomic profile of LGSOC by next generation sequencing (NGS) and evaluated its potential relationship to clinical outcomes. Methods The study included 215 women with LGSOC with: 1) pathologically confirmed LGSOC, 2) availability of NGS data, and 3) adequate clinical data. Clinical subgroups were compared for progression-free survival (PFS) and OS. Multivariable Cox regression analysis was performed. Results Median age at diagnosis was 46.6 years. The majority had a stage III ovarian primary. One or more mutations were identified in 140 (65.1%) cases; 75 (34.9%) had none. The most common mutations were KRAS (n = 71; 33.0%), NRAS (n = 24; 11.2%), and BRAF (n = 18; 8.4%). Patients with MAPK-mutated tumors (n = 113) (52.6%) had a significantly longer OS compared to those with tumors lacking MAPK pathway mutations (n = 102) (47.4%) [median OS, 147.8 months (95% CI,119.0–176.6) versus 89.5 months (95% CI, 61.4–117.7) (p = 0.01)], respectively. Median OS for patients with MAPK-mutated tumors was also significantly better than for patients whose tumors had no mutations (n = 75) [median OS, 147.8 months (95% CI, 119.0–176.6) versus 78.0 months (95% CI, 57.6–98.3)], respectively (p = 0.001). Median OS for patients with non-MAPK-mutated tumors (n = 27) was 125.1 months (95% CI, 83.9–166.3). In multivariable analysis, having a MAPK mutation was associated with improved OS. Conclusions Patients with MAPK-mutated tumors have a significantly improved OS compared to those without MAPK-mutated tumors.