Main Session
Sep
29
PQA 06 - Genitourinary Cancer, Gynecological Cancer, and Health Care Access and Engagement
3769 - Pelvic Radiation and Female Sexual Health: A Dosimetric Feasibility Study of the Bulboclitoris as an Organ-at-Risk in Gynecologic Cancers
Presenter(s)
Lamees El Nihum, MD, MEng - Fox Chase Cancer Center, Philadelphia, PA
L. I. El Nihum1, A. A. Abbasi2, M. T. Khan3, S. Y. Andrabi3, E. Hernandez4, N. Griffin5, K. Ruth6, R. Gleason1, H. N. Yankey1, and J. G. Price1; 1Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA, 2Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 3Department of Radiology, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 4Department of Obstetrics, Gynecology and Reproductive Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 5Department of Biomedical Education and Data Science, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 6Biostatistics and Bioinformatics Facility, Fox Chase Cancer Center, Philadelphia, PA
Purpose/Objective(s):
The bulboclitoris (BCS) is an erectile sensory organ responsible for female sexual arousal and orgasm. While the penile bulb is a recognized organ-at-risk with standardized contouring guidelines and dose constraints, the impact of external beam radiation therapy (EBRT) on the BCS and female sexual health are unknown. In this study, we evaluate dosimetric feasibility of dose reduction to the BCS in gynecologic cancer patients treated with pelvic EBRT.Materials/Methods:
This is a single institution retrospective study. Patients treated with pelvic EBRT for gynecologic cancer from 2022-2025 who had pelvic magnetic resonance imaging (MRI) available were included. For all patients, computed tomography (CT)-based contouring of the BCS was performed individually by the first author, principal investigator, and two pelvic radiologists, with guidance from fused pelvic MRI. Consensus CT-based contouring guidelines were composed for the superior, inferior, lateral, medial, anterior, and posterior borders of the BCS. Contouring guidelines were reviewed with expert opinion from a gynecologic oncologist and anatomist. Standard EBRT plans were accessed for each patient and BCS-sparing plans generated by our chief dosimetrist using consensus contours. Planning target volume coverage was normalized to D95.0% greater than or equal to the prescription dose. Dose reduction (cGy) to the BCS was assessed using a paired t-test.Results:
We identified 20 patients treated with pelvic EBRT for gynecologic cancer who had available pelvic MRI. Median age was 59 years (range 33 to 85). Primary cancer types were 70% (14/20) cervical, 25% (5/20) endometrial, and 5% (1/20) vaginal. Patients received a standard EBRT dose of 4500 cGy, with boost up to 5000, 5500, or 5625 cGy to gross disease. The median and mean BCS volumes were 22.6 and 21.6 cm3, respectively. The mean Dmean to the BCS was 1172.9 cGy (range 165.8 to 4322.9) versus 952.2 cGy (range 154.8 to 4060.4) for standard EBRT versus BCS-sparing plans. The mean Dmean absolute dose reduction to the BCS was 220.8 cGy (range -1171.5 to +0.6) (p = 0.005), and mean Dmean percent dose reduction to the BCS was 15.1% (range -39.4 to +0.0) (p < 0.0001). The mean Dmax to the BCS was 2155.3 cGy (range 235.4 to 5189.4) versus 1915.3 cGy (range 224.9 to 5141.1) for standard EBRT versus BCS-sparing plans. The mean Dmax absolute dose reduction to the BCS was 240.0 cGy (range -1490.5 to +72.6) (p = 0.026), and mean Dmax percent dose reduction to the BCS was 11.3% (range -43.8 to +0.0) (p = 0.0006).Conclusion:
Dose reduction to the BCS is dosimetrically feasible in patients undergoing pelvic EBRT for gynecologic cancer. Collaborative standardization of contouring guidelines is an important next step toward further study of this structure in patients undergoing pelvic EBRT, as well as pelvic brachytherapy, for various cancers. Future studies into the impact of BCS-sparing on female sexual health, and exploration of BCS dose constraints, are warranted.