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

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; I-2 = 81.2%, p(heterogeneity) = 0.005) or all non-mesenchymal subtypes (HR = 1.65, 95% CI: 0.97-2.80, p = 0.063; I-2 = 79.4%, p(heterogeneity) = 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; I-2 = 71.6%, p(heterogeneity) = 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.

Automated summary

This study aimed to investigate the relationship between subtypes of high-grade serous ovarian carcinoma (HGSOC) and survival outcomes. The results showed no statistically significant differences in overall survival (OS) between the mesenchymal subtype and other subtypes of HGSOC, but a significant difference was observed in progression-free survival (PFS). Further evidence is needed to confirm the conclusion that the mesenchymal subtype may have a poorer PFS.