Better or worse? The prognostic role of the mesenchymal subtype in patients with high-grade serous ovarian carcinoma: A systematic review and meta-analysis

Abstract

Background: Tumor characteristics can be prognostically relevant in patients with high-grade serous ovarian carcinoma (HGSOC). This study aimed to determine whether different subtypes of HGSOC, especially the mesenchymal subtype, are associated with overall survival (OS) or progression-free survival (PFS) in patients with HGSOC. Methods: PubMed, Embase, and the Cochrane Library were searched for studies published up to September 2020. The eligibility criteria were (1) population: patients with HGSOG with molecular subtyping of their tumor, (2) exposure: mesenchymal subtype, (3) non-exposure: differentiated, immunoreactive, proliferative, and other non-mesenchymal subtypes, (4) outcome: survival, with hazard ratios (HRs), and (5) English language. Results: The mesenchymal subtype showed no statistically significant difference in OS compared with the immunoreactive subtype (HR = 1.47, 95% CI: 0.78–2.78, p = 0.238; I2 = 81.2%, pheterogeneity = 0.005) or all non-mesenchymal subtypes (HR = 1.65, 95% CI: 0.97–2.80, p = 0.063; I2 = 79.4%, pheterogeneity = 0.008). The mesenchymal subtype showed no statistically significant difference in PFS compared with the immunoreactive subtype (HR = 1.19, 95% CI: 0.71–2.00, p = 0.514; I2 = 71.6%, pheterogeneity = 0.030) but a significant differences was observed when using all non-mesenchymal subtypes as reference (HR = 1.51, 95% CI: 1.00–2.28, p = 0.049). The results were robust according to the sensitivity analyses. Conclusions: There are no statistically significant differences in OS between the mesenchymal subtype of HGSOC and other subtypes of HGSOC. Because of statistical power, this meta-analysis cannot conclude about non-inferiority, and the relationship between the molecular subtypes and HGSOC prognosis remains controversial. Based on one study, the mesenchymal subtype could have a poorer PFS than the non-mesenchymal subtypes of HGSOC, but this conclusion requires further evidence.