PPP02 Presentation Time: 10:39 AM

Purpose

Erectile function is a significant quality of life consideration for patients electing definitive radiation therapy. We compared erectile outcomes following low dose rate (LDR) relative to stereotactic body radiation therapy (SBRT) as monotherapy for patients with localized prostate cancer.

Methods/Materials

Using a prospectively collected institutional database, we retrospectively analyzed the charts of patients who underwent LDR (I-125; 144Gy or Pd-103; 125Gy) brachytherapy or SBRT as monotherapy for prostate cancer and were potent (IIEF-5>20) at baseline. Patient-reported erectile function was measured at baseline at each post-treatment followup using IIEF-5 (International Index of Erectile Function). The use of erectile medications was also collected at each timepoint. Clinical (smoking history (none vs former/current), hypertension(yes/no) diabetes (yes/no) and dosimetric parameters were also collected.

Results

The study cohort included 112 patients undergoing LDR and 171 patients undergoing SBRT with a median followup of 31 months for both cohorts. Mean D90% for brachytherapy patients was 111.4%. Median SBRT dose was 4000 (range 3750-4500). 92% of patients received 4000 cGy. Mean age for SBRT patients is 66.7 years (SD±6.8) and 60.5 (SD±71) for brachytherapy patients (p<.001). There were no significant difference in smoking status (p=0.317), hypertension (p= 43) or diabetes (p= 0.18) between cohorts. There was no difference between cohorts with respect to mean baseline IIEF (27; range (21-30) (p=0.8). Mean IIEF at 12 mo ±3 was 20.6 for SBRT group versus 24.1 for brachytherapy group (P=.007). At 18 mo±3 mo, it was 20.35 for SBRT group versus 23.28 for brachytherapy group (P=.03). At 24 mo±3mo, it was 20.2 for the SBRT group versus 25.9 for the brachytherapy group (P<.001). 63% (N=107) versus 72% (N=79) patients in the SBRT and brachytherapy group, respectively, were on ED medications following treatment (P=.07).

Conclusion

Overall erectile preservation with IIEF >20 is high with both LDR and SBRT monotherapy. Higher mean IIEF scores were noted at multiple timepoints for LDR compared with SBRT. Further analyses are needed to assess whether these differences are clinically meaningful.