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Prostate volume change after radioactive seed implantation: possible benefit of improved dose volume histogram with
J L Speight1, K Shinohara, B Pickett
1Department of Radiation Oncology, University of California at San Francisco, San Francisco, CA 94143, USA.
Purpose:
To evaluate the changes in prostate volume associated with radioactive seed implantation and identify factors that influence prostate swelling.
Methods And Materials:
Between June 1997 and August 1999, 161 patients implanted for prostate carcinoma at the University of California, San Francisco, had prostate volume measurements taken at 4 time points (preplan, preimplant, postimplant, postimplant dosimetry). Patient records were reviewed for treatment with perioperative steroids, hormone therapy (nHT), and external beam radiotherapy (EBRT). One and 2-way analysis of variance (ANOVA) methods were used to test differences in mean effects among patient subsets.
Results:
A mean 20% volume increase was noted immediately postimplant overall (p < 0.0001), and even with EBRT and/or HT. Steroids were associated with a mean volume decrease of 19.9%, by 3-4 weeks post-procedure (p < 0.0001). Without steroids, only a 3.8% mean change was seen (p = ns). Steroid use resulted in a significant increase in mean dose-volume histogram (DVH) (p = 0.001); however, this benefit was only observed among patients who did not receive steroid. A consistently high DVH occurred with steroid use.
Conclusion:
A significant decrease in prostate volume and improved DVH are associated with steroid use. The diminished benefit of steroid use and higher mean DVH achieved in later years suggests the existence of a significant "learning curve" for brachytherapy procedures.