Perineural invasion (PNI) is a recognized histopathological feature of salivary gland carcinoma (SGC), but its independent prognostic value across different survival endpoints has not been quantified. This study was performed to evaluate the association between PNI and multiple survival outcomes.

A comprehensive search was conducted in 4 different databases. Studies reporting multivariable-adjusted hazard ratios (HRs) for the association between PNI and prognosis in patients with SGC were eligible. Pooled HRs with 95% confidence intervals (CIs) were calculated using random-effects models. Subgroup, sensitivity, and publication bias analyses were performed to improve the robustness.

Twenty-two studies were included in this analysis. PNI was independently associated with worse overall survival (OS) (HR 2.75, 95% CI 1.83–4.12; I² = 54.8%), disease-free survival (DFS) (HR 2.48, 95% CI 1.75–3.52; I² = 48.4%), disease-specific survival (HR 1.70, 95% CI 1.11–2.60; I² = 0%), and local control (LC) (HR 1.84, 95% CI 1.38–2.45; I² = 36.1%). Subgroup and leave-one-out sensitivity analyses identified the sources of heterogeneity of the OS, DFS and LC estimates. Begg’s test suggested possible publication bias in DFS estimate.

These findings suggest that PNI is an independent adverse prognostic factor in SGC across multiple survival endpoints. Its presence should be routinely reported and considered in risk stratification, although whether it should guide adjuvant-treatment intensity requires prospective evaluation.