Preimplant factors affecting postimplant CT-determined prostate volume and the CT/TRUS volume ratio after transperineal interstitial prostate brachytherapy with 125I free seeds.
BACKGROUND
The aim was to identify preimplant factors affecting postimplant prostate volume and the increase in prostate volume after transperineal interstitial prostate brachytherapy with 125I free seeds.


METHODS
We reviewed the records of 180 patients who underwent prostate brachytherapy with 125I free seeds for clinical T1/T2 prostate cancer. Eighty-one (45%) of the 180 patients underwent neoadjuvant hormonal therapy. No patient received supplemental external beam radiotherapy. Postimplant computed tomography was undertaken, and postimplant dosimetric analysis was performed. Univariate and multivariate analyses were performed to identify preimplant factors affecting postimplant prostate volume by computed tomography and the increase in prostate volume after implantation.


RESULTS
Preimplant prostate volume by transrectal ultrasound, serum prostate-specific antigen, number of needles, and number of seeds implanted were significantly correlated with postimplant prostate volume by computed tomography. The increase in prostate volume after implantation was significantly higher in patients with neoadjuvant hormonal therapy than in those without. Preimplant prostate volume by transrectal ultrasound, number of needles, and number of seeds implanted were significantly correlated with the increase in prostate volume after implantation. Stepwise multiple linear regression analysis showed that preimplant prostate volume by transrectal ultrasound and neoadjuvant hormonal therapy were significant independent factors affecting both postimplant prostate volume by computed tomography and the increase in prostate volume after implantation.


CONCLUSIONS
The results of the present study show that preimplant prostate volume by transrectal ultrasound and neoadjuvant hormonal therapy are significant preimplant factors affecting both postimplant prostate volume by computed tomography and the increase in prostate volume after implantation.
Sugawara
Akitomo
A
Department of Radiology, Keio University School of Medicine, Tokyo, Japan. h4411@wave.plala.or.jp
Nakashima
Jun
J
Kunieda
Etsuo
E
Nagata
Hirohiko
H
Asakura
Hirotaka
H
Oya
Mototsugu
M
Shigematsu
Naoyuki
N
D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use; D001918:Brachytherapy; D003131:Combined Modality Therapy; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D011467:Prostate / Q000000981:diagnostic imaging*; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography
D018931:Antineoplastic Agents, Hormonal; D007457:Iodine Radioisotopes