2825 - First Report of Bulboclitoris Dosimetry and Sexual Toxicity after Gynecologic Cancer Interstitial Brachytherapy

10:45am - 12:00pm PT

Hall F

Screen: 13

POSTER

Presenter(s)

Juhi Purswani, MD - Hartford Healthcare, Hartford, CT

J. Purswani¹, S. Ganey-Aquino², B. Van Nguyen³, T. Duckworth², G. N. Cohen⁴, N. Hindman⁵, and S. C. Lymberis¹; ¹Department of Radiation Oncology, New York University Grossman School of Medicine, New York, NY, ²Department of Radiation Oncology, New York University Langone Health, New York, NY, ³Radiation Oncology, Laura and Isaac Perlmutter Cancer Center, NYU Grossman School of Medicine, New York, NY, ⁴Department of Radiation Oncology, NYU Grossman School of Medicine, New York, NY, ⁵Department of Radiology, NYU Langone Health, New York, NY

Purpose/Objective(s): The aim of this study was to assess bulboclitoris (BC) dosimetry and sexual toxicity among women with gynecologic malignancies who completed interstitial brachytherapy for tumors involving the lower vagina and periurethral region.

Materials/Methods: 40 patients diagnosed with a gynecologic malignancy and treated with external beam radiotherapy (EBRT) and high dose rate (HDR) interstitial brachytherapy (BT) from 2017-2023 were retrospectively identified. The BC, including body, crura and vestibular bulbs was contoured retrospectively on CT simulation images for external beam radiotherapy planning, and for interstitial BT. CT images were fused to T2 and VIBE MRI sequences also acquired pre-treatment and post-operatively at time of brachytherapy.

Patients were divided into 3 groups based on overlap of the BC volume within the external beam EB-CTV and Brachytherapy HR-CTV: 1) no overlap (NO), 2) EB-CTV overlap (EB), and 3) EB+HR-CTV overlap (BT). Cumulative dose volume histograms for the BC were extracted for each group for the total EBRT and brachytherapy treatment course in equivalent dose in 2Gy fractions (EQD2). Median follow up, local control and vaginal morbidity using CT-CAE v4.0 for vaginal stenosis was evaluated. Sexual function assessed using an adapted questionnaire evaluating clitoral pain, clitoral orgasm and vaginal toxicity.

Results: All patients underwent IMRT EBRT to the pelvis and bilateral inguinal region (45-50.4 Gy) followed by HDR interstitial brachytherapy for a median total dose of 25.5 Gy (22-28 Gy). Median total dose to the HR-CTV D90 from EBRT and brachytherapy was 82.5 Gy (58.6-96.8). At the time of brachytherapy, 58% (33% - 77%) of total interstitial needles were placed within the bulbs of BC. Median volume of the BC was 17.6cc (6.4-35.1). 12.5% of patients were in NO group with D0.1cc to the BC 16.2 Gy ± 10.4 (7.2-29.1), 62.5% of patients in EB group with D0.1cc to BC 56.4Gy ± 6.8 (42.2-79.2) and 16.7% in BT group with D0.1cc to BC 113.1 Gy ± 26.0 (75.8-159.4). At 25 month follow up, 70% of patients had no evidence of disease. Grade 1-2 vaginal stenosis occurred in all patients despite vaginal dilator use. 6 patients (1 NO, 4 EB, 1 BT) engaged in vaginal intercourse and 83% reported low or no pain during vaginal penetration. Two patients (BT,NO) regained clitoral orgasm ability, while another patient(EB) lost clitoral function post RT.

Conclusion: The bulboclitoris is a sexual function organ which often is within the external beam and brachytherapy target volume and receives high doses of radiation. Anatomically BT needles traverse the BC even if BC is not part of the BT target volume which may cause damage to the organ. Our study is preliminary but demonstrates feasibility of BC contouring and evaluation of dose during gynecologic brachytherapy treatments. Larger studies are needed to evaluate dose response of the bulboclitoris in order to better counsel patients regarding toxicities after radiotherapy.