Variations of Urothelial Tight Junction Protein (Occludin) and its Correlation with Bladder Dose in Patients under Prostate Radiotherapy

The aim of this study was to assess the effects of fractionated radiotherapy (RT) on expression of urothelial tight junction protein (occluding) in patients under prostate radiotherapy. Finding a correlation between occludin expression and bladder dose for patients undergoing prostate conformal external radiotherapy was the second aim.
Urine samples of 64 patients under prostate radiotherapy were collected before and at regular intervals during and 3 months after radiotherapy. Occludin expression analysis of the collected urine samples was performed using chemical methods. The effective uniform dose to bladder was derived from the individually produced dose treatment plan of the patients.
Findings: There was a significant change in urine occludin level after initiation of the radiotherapy course compared to the baseline urine samples (P = 0.040). The threshold bladder dose that caused significant change in occludin level was 25.5 Gy (P = 0.046). This bladder dose was occurred after the 15th radiotherapy session. In addition, change in urine occludin level was compatible with frequency, urgency, and dysuria (P Significant change in occludin expression occurred during prostate radiotherapy. Our findings suggest that increase in occludin expression level of the bladder wall can be used as early markers of bladder complications for patients under prostate radiotherapy.