Dosimetric Predictors of Sexual Toxicity in Cervical Cancer Patients Treated With Definitive Chemoradiation and Magnetic Resonance Imaging-Guided Brachytherapy.

Abstract

Definitive radiation therapy for cervical cancer results in significant vaginal and sexual toxicity. Prior work has investigated dosimetric predictors of vaginal toxicity; however, sexual health outcomes are lacking. Patients with stage IB to IVA cervical cancer treated with definitive chemoradiation and magnetic resonance-guided brachytherapy were enrolled in a prospective, cross-sectional study. Sexual toxicity was assessed using 2 validated patient-reported outcome measures: Female Sexual Function Index and Female Sexual Distress Scale-Revised. Clinical and treatment data were collected by chart review. Vaginal dosimetry was abstracted from individual treatment plans, including: vaginal D_2cm3 (minimum dose to hottest 2 cm³ of vagina), International Commission on Radiation Units and Measurements rectovaginal point (point dose 5 mm posterior to the applicator at the top of vagina), lateral point (point dose 5 mm lateral to the applicator at the top of vagina), point dose at posterior-inferior border of the symphysis (PIBS), and PIBS ± 2 cm (point dose ± 2 cm to PIBS). Vaginal Total Reference Air Kerma assessed dose loading within the vagina. Descriptive statistics summarized the data. Correlations were evaluated using logistic and linear regression analyses. Between August 2018 and April 2022, 73 patients were eligible. Median age was 49 (range, 25-81), median stage was IIB, 58% had vaginal involvement at diagnosis, and 33% had vaginal involvement at brachytherapy. Patients completed patient-reported outcome measures at a median of 19 months (range, 3-63) post treatment. Criteria for sexual dysfunction and distress were met in 73% (Female Sexual Function Index ≤ 26) and 55% (Female Sexual Distress Scale-Revised ≥ 11) of participants, respectively. Cumulative International Commission on Radiation Units and Measurements rectovaginal point dose >65 Gy (odds ratio, 5.04; 95% CI, 1.18-27.99; P = .040) and Vaginal Total Reference Air Kerma (odds ratio, 1.71; 95% CI, 1.04-3.04; P = .045) were associated with increased sexual distress on multivariable analysis. Sexual health following radiation therapy for cervical cancer is a multifactorial issue. This analysis identifies a novel association between brachytherapy dosimetry and sexual toxicity. Further attention to and evaluation of vaginal doses could improve our understanding of sexual health outcomes.