Perineural invasion (PNI) in vulvar carcinoma: A review of 421 cases

Abstract

ObjectivesTo evaluate the prevalence and associated prognostic indicators in patients with vulvar carcinoma with and without evidence of perineural invasion (PNI). MethodsA retrospective review identified 421 patients with invasive vulvar carcinoma evaluated at a single institution between 1993 and 2011. Medical records were reviewed for demographic data, pathologic information and presence or absence of PNI, treatment type, and recurrence/outcome information. Variables were compared between patients with PNI to those without PNI. ResultsOf the 421 patients included in the study, 32 (7.6%) had tumors with PNI. There were no significant differences in age, race/ethnicity, smoking history, histologic subtype, or grade between the group of patients with PNI and the group without PNI. The group with PNI was more likely to have lichen sclerosus (25.0% vs. 15.4%, p = 0.024), stage III/IV disease (59.4% vs. 36.0%, p = 0.007), lymph node involvement (50.0% vs. 21.6%, p = 0.002), and lymphovascular space invasion (LVSI) (53.1% vs. 15.9%, p < 0.001). A higher proportion of patients in the PNI group underwent primary or adjuvant radiation therapy (68.8% vs. 45.0%, p = 0.016). The median follow-up was 67.1 months (range < 1.0 to 284.3). Patients with PNI had significantly shorter overall survival (OS), median 25.5 vs. 94.3 months (p < 0.001), and progression-free survival (PFS), median 17.5 vs. 29.0 months (p = 0.004). After adjusting for stage, patients with PNI had a greater risk for death and progression (OS: hazard ratio, 2.71; p < 0.001; PFS: hazard ratio, 1.64; p-value = 0.020). ConclusionPNI should be considered an independent poor prognostic factor for patients with vulvar carcinoma, and should be included as part of the pathologic analysis.