Prognostic impact of microscopic vascular invasion in renal cell carcinoma: a stage-stratified meta-analysis

Background Microscopic vascular invasion in renal cell carcinoma (RCC) is variably reported as lymphovascular invasion (LVI) or microvascular invasion (MVI), and its prognostic significance remains uncertain because prior reviews pooled heterogeneous definitions and mixed disease stages. We performed a stage-stratified systematic review and meta-analysis to evaluate the prognostic significance of microscopic vascular invasion in RCC using multivariable-adjusted hazard ratios (HRs). Methods PubMed, Scopus, Web of Science, Cochrane Library, ScienceDirect, and Google Scholar were searched from inception to October 2025. Eligible studies included adults with histologically confirmed RCC and histopathological assessment of microscopic vascular invasion. Random-effects meta-analyses pooled multivariable-adjusted hazard ratios (HRs) in localized and non-metastatic cohorts in which renal-vein and renal-sinus involvement was absent or handled separately. LVI/MVI harmonization was treated as a working reporting assumption. Localized cancer-specific survival (CSS) estimates were presented without pooling because of sparse-event model instability. Results Fifty-seven publications were included in the systematic review; 13 contributed to the primary synthesis and 11 to pooled meta-analyses. Microscopic vascular invasion was associated with worse disease-free/recurrence-free survival (DFS/RFS) in non-metastatic disease (5 studies; HR 3.56, 95% confidence interval [CI] 2.09–6.06; Moderate certainty) and localized disease (3 studies; HR 3.39, 95% CI 1.76–6.55; Low certainty). The secondary overall DFS/RFS estimate was similar (7 studies; HR 3.42, 95% CI 2.26–5.18; Moderate certainty). Non-metastatic CSS remained inconclusive (6 studies; HR 1.19, 95% CI 0.91–1.55; Low certainty). Four localized CSS estimates were not pooled because all arose from sparse-event models with low events per variable (Very Low certainty). Conclusions Microscopic vascular invasion is associated with worse recurrence outcomes in localized and non-metastatic RCC, but the magnitude remains uncertain. Localized CSS evidence is Very Low certainty and was not pooled because of sparse-data bias and model instability. These prognostic associations do not establish benefit from adjuvant treatment. Trial registration PROSPERO CRD420251147985.