Radioactive seed migration to the chest after transperineal interstitial prostate brachytherapy: extraprostatic seed placement correlates with migration.
OBJECTIVE
To examine the incidence of seed migration detected on chest X-ray and to identify the predictors associated with its occurrence.


METHODS
Between May 1998 and April 2000, 102 patients underwent permanent prostate brachytherapy at our institution and 100 were eligible for the study. Chest X-rays obtained at follow-up were examined for the number and location of seeds. The patient and treatment variables potentially associated with the occurrence and number of seed migrations were analyzed.


RESULTS
One or more seeds were identified on the chest X-rays of 55 (55%) of 100 patients. The mean number of intrathoracic seeds in patients with migration was 2.2 (range, 1-10), and the proportion of seeds that migrated to the thorax was 0.98%. The rate of extraprostatic seeds planned was 43.9%, and postimplant CT identified 37.9% in such a location. The number of seeds planned for extraprostatic placement and below the apex were statistically significant (alpha = 0.05) predictors in univariate logistic analysis. Multivariate analysis revealed the planned number of extraprostatic seeds as the only statistically significant predictor (p = 0.04).


CONCLUSIONS
Extraprostatic placement of loose seeds is associated with an increased likelihood for, and frequency of, seed migration to the thorax. Nonetheless, the small proportion of implanted seeds that migrated (<or=1%) is highly unlikely to have significant dosimetric consequences.
Eshleman
Jeffrey S
JS
Division of Radiation Oncology, Mayo Clinic, Rochester, MN 55905, USA.
Davis
Brian J
BJ
Pisansky
Thomas M
TM
Wilson
Torrence M
TM
Haddock
Michael G
MG
King
Bernard F
BF
Darby
Charles H
CH
Lajoie
Wayne N
WN
Oberg
Ann L
AL
D000368:Aged; D000704:Analysis of Variance; D001918:Brachytherapy / Q000295:instrumentation*; D005548:Foreign-Body Migration / Q000000981:diagnostic imaging*; D006352:Heart Ventricles; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D013909:Thorax; D014057:Tomography, X-Ray Computed