Lymphovascular invasion and p16 expression are independent prognostic factors in stage I vulvar squamous cell carcinoma

The objective of this study was to identify clinicopathologic parameters associated with disease outcome in FIGO stage I vulvar squamous cell carcinoma (vSqCC). The cohort consisted of 126 patients diagnosed with vSqCC in the period 2006-2016 who underwent primary vulvar surgery and evaluation of groin lymph node status. Tumors were reviewed by an experienced gynecologic pathologist. p16 and p53 protein expression by immunohistochemistry and HPV status were analyzed in 116 tumors. Clinicopathologic parameters, protein expression and HPV status were analyzed for association with progression-free and overall survival (PFS, OS). p16 expression and aberrant p53 were found in 49 (42%) and 61 (53%) tumors, respectively. Sixty-six tumors were HPV-associated (57%). Relapse was diagnosed in 35/126 (28%) of patients, and 23 (18%) died of disease. Tumor diameter > 4 cm (p = 0.013), lymphovascular space invasion (LVSI; p < 0.001), the presence of lichen sclerosus (p = 0.019), p16 expression (p = 0.007), p53 expression (p = 0.012), HPV status (p = 0.021), lymph node metastasis (p < 0.001) and post-operative radiotherapy (p < 0.001) were significantly related to OS in univariate analysis. Tumor diameter > 4 cm (p = 0.038), LVSI (p = 0.003), the presence of lichen sclerosus (p = 0.004), p16 expression (p = 0.004), HPV status (p = 0.039), lymph node metastasis (p < 0.001) and post-operative treatment (p < 0.001), were significantly related to PFS in univariate analysis. Age, BMI and surgical resection involvement were not significantly associated with OS or PFS. In multivariate Cox analysis, LVSI and p16 expression were independent prognosticators of OS (p < 0.001 and p = 0.02, respectively) and PFS (p = 0.018, p = 0.037). In conclusion, LVSI and p16 expression are independent prognostic factors in stage I vSqCC.