PO44 Presentation Time: 4:45 PM

Purpose

Vaginal intraepithelial neoplasia, or VaIN, is a pre-cancerous condition in the cell of the vagina. It has an estimated occurrence of 0.2-0.3 cases per 100,000 women in the U.S. It is classified into three groups based on histologic characteristics: low-grade (VaIN 1), intermediate-grade (VaIN 2), and high-grade (Vain 3). High-grade lesions includes vaginal carcinoma-in-situ and are known as a pre-malignant lesion most likely to progress to vaginal cancer. Risk factors include HPV, cigarette smoking and immunodeficiency. VaIN 1 are usually treated with close observation; VaIN 2 and 3 usually require prompt treatments including excision (wide local excision, partial or total vaginectomy), ablation (CO2 laser, ultrasonic surgical aspiration), topical therapy (imiquimod, fluorouracil), and radiation therapy. Yet no standard treatment exists. Given that it is a rare pre-malignant condition, there have been limited reports on the use of intracavitary brachytherapy. Proper dose prescription remains challenging, especially for patients with history of hysterectomy.

Materials and methods

We report a case of a 70 year-old female with history of hysterectomy 15 years ago for endometriosis and recurrent diffuse VaIN3 that was refractory to multiple lines of local therapy who received HDR cylinder brachytherapy. The report includes clinical and diagnostic studies, dosimetric considerations in treatment planning for improved target coverage, and a review of the limited existing literature of HDR brachytherapy for VaIN3.

Results

HDR, MDR and LDR had all been utilized to treat VaIN with comparable tumor control and toxicity. Reported acute side effects include vaginitis, urethritis, and proctitis; whereas late side effects include vaginal atrophy/fibrosis/telangiectasia/stenosis. What made this case especially challenging is her past surgical history of hysterectomy. The vaginal vault is difficult to assess after hysterectomy with potential abnormal cells sequestered above the suture line, and is thus prone to underdosing. Therefore some institutions prefer to use ovoids rather than cylinder to adequately cover the upper vagina; whereas others argue that cylinder is better for treating extensive lesions by providing a uniform coverage of the entire vagina despite higher toxicity. Upper vagina is also noted to tolerate a higher radiation dose compared to lower vagina. Doses are often prescribed to different depths based on location in the vagina, or on doses to the OARs. Our patient was treated with a dose of 30Gy in 5 fractions given twice weekly, prescribed to 3mm depth for the proximal 3cm vagina and to surface for the remaining 5cm vagina. She had complete clinical response and was encouraged to continue vaginal dilator use to prevent vaginal stenosis and regular follow-ups with pelvic exams.

Conclusions

HDR brachytherapy is a feasible and effective alternative approach to treat patients who are non-surgical candidates, have recurrent disease or disease refractory to previous treatments, or have extensive multifocal VaIN. Our case would be a valuable addition to the existing limited literature regarding the treatment efficacy and proper dose prescription for this rare condition.