Intrafractional Vaginal Dilation in Anal Cancer Patients Undergoing Pelvic Radiotherapy (DILANA) - a Prospective, Randomized, 2-armed Phase-II-trial

Background: The incidence of anal cancer is rising in the last decades and more women are affected than men. The prognosis after chemoradiation is very good with complete remission rates of 80-90%. Thus, reducing therapy-related toxicities and improving quality of life are of high importance. With the development of new radiotherapy techniques like IMRT (Intensity-modulated radiotherapy), the incidence of acute and chronic gastrointestinal toxicities has already been reduced. However, especially in female anal cancer patients genital toxicities like vaginal fibrosis and stenosis are of great relevance, too. Up to now, there are no prospective data reporting incidence rates, techniques of prevention or impact on quality of life. The aim of the DILANA trial is to evaluate the incidence and grade of vaginal fibrosis, to optimize radiotherapy by reducing dose to the vaginal wall to minimize genital toxicities and improve quality of life of anal cancer patients.

Methods: The study is designed as a prospective, randomized, two-armed, open, single-center phase-II-trial. Sixty patients will be randomized into one of two arms, which differ only in the diameter of a tampon used during treatment. All patients will receive standard (chemo) radiation with a total dose of 45-50.4 Gy to the pelvic and inguinal nodes with a boost to the anal canal up to 54-60 Gy. The primary objective is the assessment of the incidence and grade of vaginal fibrosis 12 months after (chemo) radiation depending on the extent of vaginal dilation. Secondary endpoints are toxicities according to the CTC AE version 5.0 criteria, assessment of clinical feasibility of daily use of a tampon, assessment of compliance for the use of a vaginal dilator and quality of life.

Discussion: Prospective studies are needed evaluating the incidence and grade of vaginal fibrosis after (chemo) radiation in female anal cancer patients. Furthermore, the assessment of techniques to reduce the incidence of vaginal fibrosis like intrafractional vaginal dilation as well as other radiotherapy-independent methods like using a vaginal dilator are essential. Additionally, implementation of a systematic assessment of vaginal stenosis is necessary to grant reproducibility and comparability of future data.

Trial Registration: The trial is registered with clinicaltrials.gov (NCT04094454, 19.09.2019).