Main Session
Sep
29
PQA 06 - Genitourinary Cancer, Gynecological Cancer, and Health Care Access and Engagement
3325 - Long-Term Changes in Sexual Function After Carbon Ion Radiotherapy for Localized Prostate Cancer: A Five-Year Prospective Study
Presenter(s)
Yoshiyuki Miyazawa, MD, PhD - Gunma University Department of Urology, Maebashi, Gunma
Y. Miyazawa1, H. Kawamura2, Y. Miyasaka2, M. Onishi2, T. Kaminuma3, S. Arai1, Y. Sekine1, T. Ohno2, and K. Suzuki1; 1Department of Urology, Graduate School of Medicine, Gunma University, Maebashi, Japan, 2Department of Radiation Oncology, Graduate School of Medicine, Gunma University, Maebashi, Japan, 3Department of Radiation Oncology, Shibukawa Medical Center, Maebashi, Japan
Purpose/Objective(s):
Carbon ion radiotherapy (CIRT) has gained attention as a curative treatment option for localized prostate cancer (PCa) because of its favorable dose distribution and potential to reduce toxicity. However, prospective data on long-term sexual function after CIRT remain limited. This study aimed to evaluate longitudinal changes in sexual function over five years in patients with localized PCa treated with CIRT.Materials/Methods:
Patients with clinically localized PCa (T1–3N0M0) who underwent CIRT between 2010 and 2013 were prospectively enrolled. Risk classification was based on initial prostate-specific antigen (PSA), Gleason score (GS), and clinical T stage. Low-risk patients (T1c–T2b, PSA <10 ng/mL, GS =6) received CIRT alone; intermediate-risk patients received 6 months of neoadjuvant androgen deprivation therapy (ADT); and high-risk patients (=T3, PSA =20 ng/mL, or GS =8) received neoadjuvant ADT for 6 months plus adjuvant ADT for 1 year. CIRT was delivered at a total dose of 57.6 Gy (RBE) in 16 fractions. Sexual function was assessed using the Expanded Prostate Cancer Index Composite (EPIC) at baseline and during follow-up for up to five years. This study was approved by the institutional ethics committee (approval no. 693).Results:
A total of 309 patients were analyzed. The mean EPIC sexual function summary score significantly declined from baseline at 1 month, 1 year, and 5 years after treatment. The sexual function (SF) domain showed a similar pattern, whereas the sexual bother (SB) domain did not significantly change throughout follow-up. Over five years, the summary and SF scores decreased by 18.0% and 31.3%, respectively (p < 0.05). Both the summary and SF scores demonstrated significant negative correlations with age, while SB did not. Younger patients showed significant declines in the summary and SF scores at five years, whereas older patients did not exhibit significant changes. When patients were stratified according to the median baseline summary score (44.9), those with higher baseline function experienced a marked immediate decline (43.9%), with partial recovery but persistent impairment (38.5% below baseline) at five years. In contrast, patients with lower baseline scores remained generally stable without significant deterioration.Conclusion:
Sexual function significantly declined after CIRT and remained impaired for up to five years, particularly in patients with better baseline function and in younger individuals. In contrast, sexual bother was relatively unchanged over time.