Vaginal intraepithelial neoplasia (VAIN) is a rare pre-malignant lesion of the female genital tract. Like cervical squamous intraepithelial lesions, Human Papillomavirus (HPV) infection represents the main risk factor and three grades of VAIN can be identified, according to the depth of epithelial involvement. However, there is still controversial data about HPV detection rate in VAIN and prognostic factors of recurrence and progression to malignancy. The aim of this study was to investigate any correlation between HPV genotype and grade of VAIN and between pre-treatment HPV genotype and risk of recurrence and/or progression.
Women attending the European Institute of Oncology, Milan, and the IRCCS Fondazione Policlinico San Matteo, Pavia, from January 2000 to December 2016, were enrolled in a multicentre retrospective study. Clinical and histological characteristics of all patients were recorded. Only patients in which HPV testing was performed at the moment of diagnosis were selected. The presence of HPV DNA was evaluated with the Cobas HPV assay in Milan and with the INNO-LiPA genotyping system in Pavia. For our analysis, results of both HPV tests were classified as HPV 16-18, other pooled High Risk (HR)-HPV and negative HR-HPV. The χ2-test was used to evaluate associations and a P-value <0.05 was considered statistically significant.
Among 266 patients enrolled, only 167 diagnosed with VAIN1 (59), VAIN2 (42) and VAIN3 (66) were suitable for this analysis. The median follow-up time was of 23.6 months (95% CI: 18.8 – 30.1). HPV 16-18 was detected in 12 (20.3%) VAIN1, 13 (30.9%) VAIN2 and 37 (56.1%) VAIN3, whereas other HR-HPV in 36 (61.0%) VAIN1, 24 (57.1%) VAIN2 and 21 (31.8%) VAIN3 (p<0.001). Overall, 48 (28.7%) recurrences/progressions occurred, with a median time of progression free survival of 93.4 months. No statistical difference was found in number of relapses between pre-treatment HPV 16-18 (22) and other HR-HPV (21) (p=0.26).
HPV 16-18 represent the main genotypes associated with the development of high-grade VAIN, whereas other HR-HPV are more frequently related to low-grade VAIN. Nevertheless, pre-treatment HPV genotype does not affect the risk of recurrence and/or progression of vaginal dysplasia.