Radical prostatectomy can cause penile hypoxia, fibrosis, and calcifications: a pilot study

BACKGROUND: Peyronie's disease (PD) is defined as a fibrotic disease of the penis resulting in plaque formation and abnormal penile curvature. The incidence of PD has been suggested to increase after radical prostatectomy (RP). Hypoxia in the corpus cavernosum secondary to nerve injury has been suggested to be one of the causative factors for development of erectile dysfunction following RP. It is also known that hypoxia can cause fibrosis in vitro and in animal models. We therefore hypothesized that men who develop PD after RP do so due to hypoxia. AIM: To investigate if hypoxia and fibrotic changes can be detected in men undergoing RP. METHODS: Erectile function and PD were assessed before, 3 and 6 months after RP using International Index of Erectile Function (IIEF) and PD questionnaires, stretched penile length and nocturnal penile tumescence. Fibrosis was investigated by ultrasonography (USG) and tissue oxygen levels were measured using oximetry. OUTCOMES: The primary outcome was a significant decrease in flaccid penile oxygen levels in men as measured before and after RP. RESULTS: All 24 men completing the study developed fibrotic changes and calcification confirmed by USG and showed significant decrease in penile oxygen levels after RP. The patients' IIEF scores and Peyronie's disease questionnaire also showed a significant decrease in erectile function without any patient-reported curvatures. Stretched penile length was also reduced significantly. There was a significant correlation between calcification and oxygen levels between post-op 3 months and 6 months. CLINICAL IMPLICATIONS: RP can cause penile fibrosis which may be due RP-associated hypoxia in the penis. Prostate surgeons should consider discussing this risk with their patients before the operation. STRENGTHS AND LIMITATIONS: USG and oximetry readings before and after the RP allowed us to observe the effect of the surgery within individual patients. A larger study with a longer follow up would be needed to confirm these findings and to investigate a correlation between plaque formation and oxygen levels. CONCLUSION: In this study, all the patients developed fibrotic changes, calcification and a decrease in penile oxygen levels following RP. This is the first demonstration of a significant decrease in penile oxygen levels following RP. A correlation between calcification and low oxygen levels suggests that hypoxia-induced fibrosis may be the cause of calcification during the progression of PD.