Elsevier

Urology

Volume 66, Issue 1, July 2005, Pages 119-123
Urology

Adult urology
Reduction of pulmonary migration of permanent interstitial sources in patients undergoing prostate brachytherapy

https://doi.org/10.1016/j.urology.2005.01.047Get rights and content

Abstract

Objectives

To investigate a method to decrease the problem of seed migration after permanent prostate brachytherapy. Permanent prostate brachytherapy can be performed by a number of techniques using several different seed configurations. All have been associated with some degree of pulmonary seed migration, and no studies have clearly investigated a means of decreasing this problem.

Methods

A total of 238 patients underwent implantation with either iodine-125 (I-125; 146 patients) or palladium-103 (92 patients). The implant was performed in real time using an applicator, with the sources placed just underneath the prostatic capsule. Postimplant dosimetry was performed at 1 month. Routine chest x-ray was obtained a minimum of 4 months after implantation; 24 patients had a second chest x-ray taken.

Results

A total of 21,654 seeds were implanted (median 89, range 27 to 220). Postimplant chest x-rays were obtained at a median of 912 days (range 147 to 3023), and 4 patients (1.7%) experienced at least one seed embolus to the lung. Of the 21,654 seeds, 10 (0.005%) were found in the lungs. All 4 patients had received an I-125 implant, resulting in a pulmonary embolus rate for I-125 of 2.7% (4 of 146) and for palladium-103 of 0% (0 of 92). No patients experienced subsequent seed migration if it was not seen on the initial film. The median dose delivered to 90% of the prostate volume for all patients undergoing I-125 implantation was 172 Gy and for the 4 patients with seed migration it was 174 Gy.

Conclusions

Seed embolism to the lungs is a rare event when patients undergo implantation using the real-time method. Although in our series migration was slightly greater with I-125 than with palladium-103, no negative effect was seen on the postimplant dosimetry results.

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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