Eva Bieniek, Presenter: Nothing to Disclose

Hani L. Ashamalla MD, Abstract Co-Author: Nothing to Disclose

Adel Guirguis MBBCh, Abstract Co-Author: Nothing to Disclose

Prostate brachytherapy (PB) is associated with increase in prostate volume (PV) in the immediate post-operative period. This study evaluates post-operative pattern in PV changes and examines potential variables that might affect prostate swelling.

Twenty four patients (pts) were analyzed. Twelve pts were treated with PB only and 12 pts were treated with PB and external beam radiation (EBRT), as clinically indicated. Out of the 12 pts treated with both modalities, 8 received EBRT prior to implant while 4 received EBRT after PB. Measurements of the pre (PV0) and post-implant volumes were done using pelvic computed tomography with urethrogram. Post-implant PV measurements were done on day 1(PV1), 9(PV9), 30(PV30), and 60(PV60). The influence of several variables on the degree of PV changes was examined using univariate analysis. The variables analyzed included: PV0, seed activity (0.3 vs 0.5mCi), hormonal ablation therapy, EBRT, the number of needles, seeds, and needle insertion attempts. Urinary symptoms were assessed using International Prostate Scoring System (IPSS).

Single observer performed 96 PV measurements. PV0 ranged from 27.1 to 89.4 cc (mean 48.2). Largest PV was observed on day 1 (40.1-118.7, mean 67.1). Prostate size then continuously decreased. Mean PV values on day 9, 30, and 60 were 58.6, 51.5, and 42.3cc, respectively. The differences between PV0 and all successive PVs were statistically significant. Mean increase in PV1 from PV0 was 18.9±16.8cc (p<0.001), PV0 and PV9 was 9.7cc, PV0 and PV30 was 2.6cc. PV60 was smaller than PV0 by an average of 6.6cc. Higher seed activity was associated with greater prostate swelling (p=0.02), and treatment with EBRT prior to PB was associated with less prostate edema (p=0.043). Other variables were not significantly correlated with PV changes. Although the mean IPSS score increased from pre-implant value of 9.2 to 13.7 on day 60, the differences between IPSS values were not statistically significant.

Maximum prostate size is observed on the first day after the implant. Prostate edema begins to subside in the first week after the procedure and prostate returns to pre-implant volume between day 30 and day 60. Increased prostate swelling is noted with higher seed activity, while less swelling occurs in patients treated with external radiation prior to implant. Resolution of prostate swelling does not appear to parallel with improvement in urinary symptoms in the first 2 months after implant. Influence of prostate swelling on dosimetry will be reported.

Bieniek, E, Ashamalla, H, Guirguis, A, Determinants of Prostate Volume Changes Following Iodine-125 Interstitial Prostate Implant.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/6001594.html