Vulvar High-Grade Squamous Intraepithelial Lesions Treated with Imiquimod: Can Persistence of Human Papillomavirus Predict Recurrence?

SIMPLE SUMMARY: Vulvar high-grade intraepithelial lesion (vulvar HSIL) is a premalignant vulvar condition that requires intervention, usually surgery. It recurs frequently, and its treatment involves repeated disfiguring surgeries. Vulvar HSIL is associated with human papillomavirus. Imiquimod is a medical treatment option currently attracting attention because vulvar high-grade intraepithelial neoplasia is frequent in young women with multiple vulvar lesions. Few studies have evaluated the long-term effects of the response to imiquimod and the association of human papillomavirus with response and recurrence. We describe a retrospective (with cases already treated) study designed to determine the long-term response to imiquimod in patients with vulvar HSIL, and also to analyze the role of human papillomavirus (HPV), and different HPV types, in the persistence or recurrence of vulvar HSIL after imiquimod treatment. ABSTRACT: Objectives: Vulvar high-grade squamous intraepithelial lesion (vulvar HSIL) or vulvar intraepithelial neoplasia (VIN) is a premalignant condition that can progress to carcinoma. Imiquimod is a topical drug with high effectiveness and low morbidity. We aimed (1) to assess the long-term response to imiquimod in a cohort of patients with vulvar HSIL and (2) and to analyze the role of HPV determined in pre- and post-imiquimod treatment biopsies in the persistence or recurrence of vulvar HSIL. Design: Retrospective study between 2011 and 2022. Setting: Referrals from the primary care area of Baix Llobregat treated in the gynecology department of a university hospital in Barcelona, Spain. Population: 20 women with vulvar HSIL treated with imiquimod. Methods: The inclusion criteria were vulvar HSIL, vulvar HPV determination by pre- and post-treatment biopsy, acceptance of medical treatment, at least one follow-up and 4 weeks of treatment. Main outcome measures: Histological diagnosis of vulvar HSIL with pre- and post-imiquimod HPV determination. Response to treatment (complete, partial, no response, recurrence). Results: After imiquimod, 10 (50%) and 6 (30%) cases had complete and partial responses, respectively. Another 4 cases (20%) did not respond. Before treatment, 19 (95%) cases were positive for vulvar HPV (16 cases had HPV type 16). After treatment, 10 cases (50%) were positive for HPV (8 cases with HPV type 16): 2 cases (20%) with a complete response, 5 cases (83.3%) with a partial response and 3 cases (75%) with no response. Eight of the 10 HPV-negative cases (80%) post-treatment showed a complete response. HPV type 16 was present in 16 cases (84.2%) pre-treatment and in 8 cases (80%) post-treatment. Ten patients underwent additional treatments following a partial response, no response or recurrence. The 2 HIV and 3 immunosuppressed patients treated with imiquimod showed a partial response and required additional treatment. All these patients were HPV-positive pre- and post-treatment (100%). Response to imiquimod was associated with post-treatment vulvar HPV positivity (p = 0.03). The median time to a complete response in HPV-negative cases was 4.7 months versus 11.5 months in HPV-positive cases post-imiquimod treatment. Recurrence of vulvar HSIL was observed in 7 patients (35%), with a median time to recurrence of 19.7 months (range 3.2–32.7). Recurrence was experienced in 10% of cases with a complete response, in 4/6 (66.6%) cases with a partial response, and in 2/4 (50%) women with no response. Four of the 7 recurrent cases (57%) were infected with HIV or immunosuppressed. Six (85%) of the recurrent cases were HPV-positive post-treatment (all were HPV type 16). Four (30.7%) of the non-recurrent cases were HPV-positive post-treatment with imiquimod (p = 0.05), two of which were HPV type 16 (50%). Conclusions: Imiquimod effectively treats vulvar HSIL. Cases with a complete response showed less HPV positivity post-treatment than partial or non-response cases. Recurrences were more frequent in those with a partial or no response to imiquimod, and in immunosuppressed patients. In recurrent cases, 85% were HPV-positive post-treatment, while 30.7% of non-recurrent cases were HPV-positive. HPV positivity in the post-treatment biopsy suggests the need for stricter follow-up of patients.