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.

Impact of Age and Primary Disease Site on Outcome in Women With Low-Grade Serous Carcinoma of the Ovary or Peritoneum: Results of a Large Single-Institution Registry of a Rare Tumor.

PURPOSE: Low-grade serous carcinoma of the ovary (LGSOC) or peritoneum (LGSPC) is a rare subtype of ovarian or peritoneal cancer characterized by young age at diagnosis and relative resistance to chemotherapy. The purpose of this study is to report our updated experience with women diagnosed with LGSOC or LGSPC to assess the validity of our original observations. PATIENTS AND METHODS: Eligibility criteria for patients from our database were: stage I to IV LGSOC or LGSPC, original diagnosis before January 2012, and adequate clinical information. All patients were included in progression-free survival, overall survival, and multivariable Cox regression analyses. A subset analysis was performed among patients with stage II to IV low-grade serous carcinoma treated with primary surgery followed by platinum-based chemotherapy. RESULTS: We identified 350 eligible patients. Median progression-free survival was 28.1 months; median overall survival was 101.7 months. In the multivariable analysis, compared with women age ≤ 35 years, those diagnosed at age > 35 years had a 43% reduction in likelihood of dying (hazard ratio, 0.53; 95% CI, 0.37 to 0.74; P < .001). Having disease present at completion of primary therapy was associated with a 1.78 increased hazard of dying compared with being clinically disease free (P < .001). Similar trends were noted in the smaller patient cohort. In this cohort, women with LGSPC had a 41% decreased chance of dying (hazard ratio, 0.59; 95% CI, 0.36 to 0.98; P = .04) compared with those with LGSOC. CONCLUSION: Women age < 35 years with low-grade serous carcinoma and those with persistent disease at completion of primary therapy have the worst outcomes. Patients with LGSPC seem to have a better prognosis than those with LGSOC.