Main Session
Sep 28
PQA 04 - Breast Cancer, Patient Reported Outcomes/QoL/Survivorship, Functional Radiation Medicine, Hematologic Malignancies, Palliative Care, and International/Global Oncology

2777 - Anatomical Reserve and Neurovascular Coupling in Gynecologic Cancer Survivorship: A Two-Part Hurdle Analysis of Patient-Reported Sexual Function

03:00pm - 04:00pm ET
Poster Hall - Exhibit Hall A
Screen: 28
POSTER

Presenter(s)

cheng-Hsueh Kuo, MD Headshot
Cheng-Hsueh Kuo, MD - National Taiwan University Hospital, Taipei, Taipei

C. H. Kuo1, C. Y. J. Hsu1,2, Y. J. Tai3, Y. C. Chiang3, I. L. Shih4,5, Y. S. Huang4,5, and J. L. Y. Chen1,2; 1Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan, 2Department of Radiation Oncology, National Taiwan University Cancer Center, Taipei, Taiwan, 3Department of Obstetrics and Gynecology, National Taiwan University Hospital, Taipei, Taiwan, 4Department of Medical Imaging, National Taiwan University Hospital, Taipei, Taiwan, 5Department of Radiology, National Taiwan University College of Medicine, Taipei, Taiwan

Purpose/Objective(s):

Chronic sexual dysfunction following pelvic radiotherapy (RT) is often hidden by zero-inflated data in patient-reported outcomes (PROs). We hypothesize that sexual engagement is directly influenced by anatomical reserve, while functional quality is limited by RT-induced neurovascular toxicity. This study employs a two-part hurdle model to distinguish these pathways.

Materials/Methods:

We conducted a retrospective cohort study of 120 gynecologic cancer survivors treated with vaginal brachytherapy (VBT) alone or external beam radiotherapy (EBRT ± VBT) at a single institution from 2009 to 2023. Sexual function was measured using the 19-item Female Sexual Function Index (FSFI). To address the zero-inflated data distribution, a hurdle model was developed: (1) Activity Hurdle: Multivariable logistic regression identified predictors of sexual activity; and (2) Functional Hurdle: Multivariable Beta regression with Smithson-Verkuilen transformation analyzed functional intensity and quality among those sexually active. Covariates included age, parity, lubricant use, and EQD2. Domain collinearity was assessed with a heatmap analysis to test the coupled neurovascular injury hypothesis.

Results:

The cohort showed a severe floor effect (mean FSFI 5.9; 64.2% inactive). In the Activity Hurdle, engagement was influenced by lubricant use (OR=12.2; 95% CI 1.66-88.9; P=.01) and multiparity (=2 births: OR=12.6; 95% CI 1.74-91.8; P=.01), while RT modality was non-significant (P=.11). Conversely, in the Functional Hurdle, RT modality was the only factor affecting quality. EBRT decreased functional scores compared to VBT alone (exp(ß)=0.17; 95% CI 0.06-0.45; P=.001), representing an 83% reduction in functional odds, with notable deficits in the orgasm domain (1.3 vs 3.1; P=.02) despite preserved lubrication. Heatmap analysis revealed strong collinearity between lubrication and orgasm (r=0.94), supporting a coupled neurovascular injury specific to whole-pelvis irradiation. Active survivors showed significant overall deficits compared to historical healthy controls (P<.001), especially in orgasm, compared to historical VBT-only groups (P =.009).

Conclusion:

Sexual dysfunction following pelvic RT follows a "two-hurdle" framework. The initial barrier to activity is governed by anatomical (parity) and mechanical (lubricants) support, highlighting nulliparous women as key targets for early dilation therapy. However, functional quality is largely limited by EBRT-induced neurovascular toxicity. Clinical management requires a tiered approach: employing mechanical aids to overcome activity barriers and neurovascular-sparing techniques (IMRT/VMAT) to enhance functional capacity for survivors requiring whole-pelvis radiation.