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

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

doi:10.1016/j.urolonc.2007.03.026

« Previous Next »Urologic Oncology: Seminars and Original Investigations
Volume 26, Issue 2 , Pages 147-152, March 2008

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

Michele Albert, M.D.
- Department of Radiation Oncology, Brigham and Women’s Hospital and Dana Farber Cancer Institute, Boston, MA 02115, USA
- Corresponding author. Tel.: +1-508-979-5858; fax: +1-508-984-3535.
Jun S. Song, Ph.D.
- Department of Radiation Oncology, Brigham and Women’s Hospital and Dana Farber Cancer Institute, Boston, MA 02115, USA
Delray Schultz, Ph.D.
- Department of Mathematics, Millersville University, Millersville, PA 17551, USA
Robert A. Cormack, Ph.D.
- Department of Radiation Oncology, Brigham and Women’s Hospital and Dana Farber Cancer Institute, Boston, MA 02115, USA
Clare M. Tempany, M.D.
- Department of Radiology, Brigham and Women’s Hospital and Dana Farber Cancer Institute, Boston, MA 02115, USA
Steve Haker
- Department of Radiology, Brigham and Women’s Hospital and Dana Farber Cancer Institute, Boston, MA 02115, USA
Phillip M. Devlin, M.D.
- Department of Radiation Oncology, Brigham and Women’s Hospital and Dana Farber Cancer Institute, Boston, MA 02115, USA
Clair Beard, M.D.
- Department of Radiation Oncology, Brigham and Women’s Hospital and Dana Farber Cancer Institute, Boston, MA 02115, USA
Mark D. Hurwitz, M.D.
- Department of Radiation Oncology, Brigham and Women’s Hospital and Dana Farber Cancer Institute, Boston, MA 02115, USA
Wonsuk W. Suh, M.D.
- Department of Radiation Oncology, Brigham and Women’s Hospital and Dana Farber Cancer Institute, Boston, MA 02115, USA
Ferenc Jolesz, M.D.
- Department of Radiology, Brigham and Women’s Hospital and Dana Farber Cancer Institute, Boston, MA 02115, USA
Anthony V. D’Amico, M.D., Ph.D.
- Department of Radiation Oncology, Brigham and Women’s Hospital and Dana Farber Cancer Institute, Boston, MA 02115, USA

Received 21 September 2006; received in revised form 11 March 2007; accepted 15 March 2007. published online 29 October 2007.

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.

Keywords: Prostate cancer, Brachytherapy, Quality of life