Preservation of baseline erectile function in radiotherapy patients using PDE5i
Miranda, EP1; Jenkins, L1; Nelson, C1; Zelefsky, M1; Mulhall, J1
1: MSKCC, USA
Objective: Radiation therapy (RT) as a treatment modality for prostate cancer (PC) has a known negative impact on erectile function (EF). It is believed that the use of PDE5 inhibitors (PDE5i) can help limit endothelial and smooth muscle structural changes, and, therefore, increase preservation of erectile function (EF). The aim of this study was to analyze the utility of PDE5i use on preservation of baseline EF in men undergoing RT.
Methods: Men with PC treated with RT had PDE5i use recorded. Patients completed the international index of erectile function (IIEF) questionnaire pre-RT and serially at 12, 24, 36 and 48 months after treatment. Erectile function domain (EFD) scores were analyzed. PDE5i use was recorded at the same time points and was classified as never (0), sometimes (1-2) or always (≥5 days per week). Patients received brachytherapy (BT), high dose IMRT (IMRT), or a combination of the two (CT). Patients who received androgen deprivation therapy (ADT) were excluded for the purposes of this analysis. Preservation of baseline EFD scores was investigated in each PDE5i use group.
Results: 164 men were available for analysis at baseline (12m n=140, 24m n=157, 36m n=145, 48m n=143). Mean age = 65±8 years. RT treatment group numbers were: 72 BT, 64 IMRT, and 28 CT. 22% were taking a PDE5i at baseline; at 12m, this percentage increased significantly to 44% (p=0.01) and this remained consistent throughout the remainder of follow-up. Good EF (EFD ≥24) at baseline was reported by 73%. Mean baseline EFD score for the total group = 25.2±6.5; 12m 23.5±7.8, p=0.001; 24m 22.5±8, p=0.07; 36m 22.7±8 p=NS; 48m 22.3±8.2, p=NS. No significant differences in EFD score changes were seen between the three RT modality groups. The following percentages had preservation of baseline EF: 64% at 12m, 63% at 24m, 64% at 36m, and 67% at 48m. According to PDE5i use in the first year, preservation of baseline EF at 48m was: 63% in the ‘never’ use PDE5i group, and 73% in the “always’ use PDE5i group. On multivariable analysis, age (beta=-0.20, p=0.03) and PDE5i use in the first year (beta=0.16, p=0.07) remained predictors of 48m EFD, with this relationship not detectable until 48m.
Conclusions: Preservation of baseline EF after RT for PC is maximized by regular PDE5i use. It has a protective effect on long-term EF. The effects of RT and PDE5i utilization appear to be similar across treatment modalities.
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