Urology
Volume 72, Issue 5 , Pages 1125-1129, November 2008

Does Timing of Androgen Deprivation Influence Radiation-Induced Toxicity? A Secondary Analysis of Radiation Therapy Oncology Group Protocol 9413

This study was presented as a poster at the American Society for Therapeutic Radiology and Oncology Annual Meeting, Philadelphia, November 2006.

  • Daniel Taussky

      Affiliations

    • Department of Radiation Oncology, Montreal University, Montreal, Quebec, Canada
    • Corresponding Author InformationReprint requests: Daniel Taussky, M.D., Department of Radiation Oncology, Centre Hospitalier Universitaire de Montréal Hôpital Notre-Dame, 1560 Sherbrooke Street East, Montreal, H2L 4M1 QC Canada
  • ,
  • Kyounghwa Bae

      Affiliations

    • Department of Statistics, Radiation Therapy Oncology Group, Philadelphia, Pennsylvania
  • ,
  • Jean-Paul Bahary

      Affiliations

    • Department of Radiation Oncology, Montreal University, Montreal, Quebec, Canada
  • ,
  • Mack Roach III

      Affiliations

    • Department of Radiation Oncology, University of California, San Francisco, School of Medicine, San Francisco, California
  • ,
  • Colleen A. Lawton

      Affiliations

    • Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin
  • ,
  • William U. Shipley

      Affiliations

    • Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
  • ,
  • Howard M. Sandler

      Affiliations

    • Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, Michigan

Received 3 August 2007; accepted 13 November 2007. published online 04 March 2008.

Objectives

We conducted a secondary analysis of the Radiation Therapy Oncology Group protocol 9413 to compare whether the timing of antiandrogen therapy (concomitant versus adjuvant) and testosterone levels influences the incidence of rectal and urinary toxicity in whole pelvic radiotherapy.

Methods

We analyzed two of four study arms, in which all patients received radiotherapy to the whole pelvis followed by a boost to the prostate. The two arms differed solely in the timing of the total of 4 months of total androgen deprivation: arm I (320 patients, given concomitantly) and arm III (319 patients, given as adjuvant therapy). The influence of testosterone levels (measured at baseline and yearly thereafter) and its recovery on late rectal and urinary toxicity were modeled by multivariate logistic regression analysis and Fine and Gray's regression models.

Results

The occurrence of late rectal toxicity (grade 0–1 versus 2–5, P = 0.16) and late urinary toxicity (grade 0–1 versus 2–5, P = 0.52) was not significantly different statistically between the two arms. The time to testosterone recovery was significantly lower in the adjuvant arm (mean difference of 3.2 months, P = 0.0103). Age and radiation field size are statistically significant risk factors for late urinary toxicity (P = 0.01 and P = 0.02). Baseline testosterone levels, before beginning total androgen deprivation, were a statistically significant predictive factor for late urinary toxicity (P = 0.03).

Conclusions

Older patients and patients with low testosterone levels at baseline are risk factors for late urinary and rectal toxicities, possibly through impaired tissue repair.

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 This study supported by RTOG U10, CA21661, CCOP U10 CA37422, and Stat U10 CA32115 grants from the National Cancer Institute.

 M. Roach is a study investigator funded by GlaxoSmithKline; is a paid consultant to Astra-Zeneca; and is a member of the speaker's bureau for TAP Pharmaceuticals and Siemens.

PII: S0090-4295(07)02448-X

doi:10.1016/j.urology.2007.11.067

Urology
Volume 72, Issue 5 , Pages 1125-1129, November 2008