Adult urologyReduction of pulmonary migration of permanent interstitial sources in patients undergoing prostate brachytherapy
Section snippets
Material and methods
From 1990 to 1999, 1190 patients with Stage T1-T3 prostate cancer underwent seed implantation: alone, with hormonal therapy or external beam radiotherapy, or both. Generally, patients with a prostate-specific antigen (PSA) level less than 10 ng/mL, Gleason score less than 7, and clinical Stage T2b or less underwent implantation with iodine-125 (I-125) monotherapy to a dose of 160 Gy. Those with moderate risk features, PSA level greater than 10 ng/mL or Gleason score 7 to 8 or Stage T2b-T2c, or
Results
A total of 238 patients underwent implantation with either I-125 (146 patients) or Pd-103 (92 patients) and had a CXR a minimum of 4 months afterward. Additionally, 24 patients had a second CXR. Of the 238 patients, 141 (59%) had Stage T2a or less and 175 (73.5%) had a Gleason score of 6 or less. The median PSA level was 7.5 ng/mL (range 1.3 to 124); 118 (50%) were treated with 6 to 9 months of hormonal therapy; and 39 (16.4%) underwent a combination of implantation and external beam
Comment
Seed migration has been described in as many as 55% of patients receiving permanent seeds.3 Although no long-term morbidity has been associated with seed migration, especially to the lung, the loss of sources from their intended positions could result in poorer peripheral radiation dose coverage. Several theories have been postulated that might explain seed migration. The seed shape and construction may lend itself to migration. The permanent sources are cylinder-shaped titanium shells
Conclusions
Pulmonary migration of permanent prostate sources has been a common occurrence. Proper technique in the operating room can substantially reduce this likelihood. Although the use of stranded sources can reduce the early migration of seeds, they are unlikely to prevent late migration once the strands have dissolved. Strict attention to the periprostatic venous anatomy, as defined by ultrasonography, can reduce the risk of seed migration, regardless of the technique used to insert the seeds.
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