(P30) effect of radiation therapy on penile Doppler parameters and intra-corporeal injection dosage in prostate Cancer patients

Abstract Background Radiotherapy, a standard treatment for prostate cancer, is known to adversely affect erectile function. Assessing the impact of this therapy on penile vascular health and erectile dysfunction management is essential for improving patient outcomes post-treatment. This evaluation can help optimize rehabilitation plans and enhance quality of life for those undergoing prostate cancer therapy. This study aims to explore the effect of radiotherapy on penile Doppler parameters and intra-corporeal injection (ICI) dose requirements, compared with other treatment modalities, in prostate cancer patients. Methods A retrospective analysis was performed using our institution’s database to identify patients who developed erectile dysfunction following radiotherapy. The study included individuals from a single institution who attended the Sexual Medicine clinic, underwent Penile Doppler Ultrasound, received Trimix ICI therapy, and had at least one year of follow-up, during which the ICI dosage required for satisfactory erectile response was monitored. A total of 233 patients, meeting the inclusion criteria between 2021 and 2024, were included in the analysis. Participants were divided into two groups: Group 1 consisted of patients who underwent radiotherapy, while Group 2 included those who received alternative prostate cancer treatments, such as prostatectomy or androgen deprivation therapy. Student’s T-test and Chi-squared test were utilized to compare numerical and categorical variables between the two groups, respectively. Linear regression analysis was performed to explore the impact of demographic and clinical variables on the changes in ICI trimix dose during follow-up. Results A total of 233 patients were evaluated in this study. Table 1 compares key clinical parameters between two groups: prostate cancer patients treated with radiation therapy (N = 57) and those treated with non-radiation modalities (N = 176). The prevalence of diabetes mellitus (DM) and hypertension (HTN) is comparable between the two groups, with no statistically significant differences (p = 0.53 and p = 0.36, respectively). However, the mean age of patients in the radiation group (63.58 ± 6.87 years) is significantly higher than in the non-radiation group (61.11 ± 7.51 years), with a p-value of 0.029, suggesting a meaningful age difference. No significant differences between both groups were observed in arterial parameters, including pre- and post-in office ICI arterial diameters, as well as peak systolic velocity (PSV) and end-diastolic velocity (EDV). Notably, the increase in the required dose of intra-corporeal trimix injections over time is more pronounced in the radiation group (17.31 ± 19.21) than in the non-radiation group (10.94 ± 15.7), with a p-value of 0.016. Linear regression analysis further confirmed that age (regression coefficient = 0.34, 95% CI 0.04-0.64, p = 0.02) and exposure to radiation (regression coefficient = 5.5, 95% CI 0.34-10.6, p = 0.03) were both independent predictors for an increase in trimix ICI dose during follow-up. Conclusion The findings of this study suggest that exposure to radiation therapy as well as older age were associated with a greater need for higher doses of injection therapy to achieve satisfactory erectile function in prostate cancer patients. These findings highlight the potential adverse effects of radiation on erectile recovery and underscores the need for individualized rehabilitation strategies for patients undergoing prostate cancer radiotherapy. Further studies are needed to definitively determine its clinical significance and move beyond the current status.