Defining the rectal dose constraint for permanent radioactive seed implantation of the prostate

Michele Albert, Jun S. Song, Delray Schultz, Robert A. Cormack, Clare M. Tempany, Steve Haker, Phillip M. Devlin, Clair Beard, Mark D. Hurwitz, Wonsuk W. Suh, Ferenc Jolesz, Anthony V. D'Amico

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: This study was performed to define the rectal dose constraint that would predict late rectal bleeding requiring argon plasma coagulation (APC) following prostate brachy mono-therapy. Methods and materials: Between February 1999 and April 2002, 91 patients with low risk prostate cancer underwent permanent I125 radioactive seed implantation without the use of supplemental external beam radiation or androgen suppression therapy. Patients received both CT and MRI scans 6 weeks postimplant for evaluation of dosimetry. The CT and MRI scans were fused. Rectal volumes were contoured on the T2 weighted MR images. For those patients requiring APC, the date on which a patient reported rectal bleeding was recorded. A Cox regression analysis was performed to assess whether there was a significant association between the rectal volume (continuous) exceeding 100 Gy time rectal bleeding. Comparisons of estimates of rectal bleeding requiring APC were made using a 2-sided log rank test. Results: There was a significant association (hazard ratio = 5.6 [95% confidence interval: 1.3, 23.8]; P = 0.002) between the rectal volume exceeding 100 Gy and rectal bleeding requiring APC. After a median follow-up of 4.25 (1-6) years, no patient with less than a median value of 8 cc of rectum exceeding 100 Gy required APC, whereas 20% (P = 0.004) were estimated to require APC within 3 years following treatment. Conclusions: Keeping the rectal volume receiving more than 100 Gy below 8 cc will minimize the risk of rectal bleeding requiring APC following I125 permanent prostate brachy mono-therapy.

Original languageEnglish (US)
Pages (from-to)147-152
Number of pages6
JournalUrologic Oncology: Seminars and Original Investigations
Volume26
Issue number2
DOIs
StatePublished - Mar 2008
Externally publishedYes

Keywords

  • Brachytherapy
  • Prostate cancer
  • Quality of life

ASJC Scopus subject areas

  • Oncology
  • Urology

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