Three-dimensional external beam radiotherapy for prostate cancer increases the risk of hip fracture

Authors

  • Sean P. Elliott MD,

    Corresponding author
    1. Department Urologic Surgery, School of Medicine, University of Minnesota, Minneapolis, Minnesota
    2. Division of Health Policy and Management, School of Public Health, University of Minnesota, Minneapolis, Minnesota
    • Department Urologic Surgery, University of Minnesota, 420 Delaware Street SE, MMC 394, Minneapolis, MN 55455
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    • Fax: (612) 626-0428

  • Stephanie L. Jarosek RN,

    1. Division of Health Policy and Management, School of Public Health, University of Minnesota, Minneapolis, Minnesota
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  • Shaheen R. Alanee MD, MPH,

    1. Department Urologic Surgery, School of Medicine, University of Minnesota, Minneapolis, Minnesota
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  • Badrinath R. Konety MD, MBA,

    1. Department Urologic Surgery, School of Medicine, University of Minnesota, Minneapolis, Minnesota
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  • Kathryn E. Dusenbery MD,

    1. Department of Therapeutic Radiology, School of Medicine, University of Minnesota, Minneapolis, Minnesota
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  • Beth A. Virnig MPH, PhD

    1. Division of Health Policy and Management, School of Public Health, University of Minnesota, Minneapolis, Minnesota
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  • This study used the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare database. The authors are solely responsible for the interpretation and reporting of these data. We acknowledge the efforts of the Applied Research Program, National Cancer Institute (NCI); the Office of Research, Development and Information, Centers for Medicare and Medicaid Services (CMS); Information Management Services (IMS), Inc; and the SEER Program tumor registries in the creation of the SEER-Medicare database.

Abstract

BACKGROUND:

Hip fracture is associated with high morbidity and mortality. Pelvic external beam radiotherapy (EBRT) is known to increase the risk of hip fractures in women, but the effect in men is unknown.

METHODS:

From the Surveillance, Epidemiology, and End Results (SEER)-Medicare database, 45,662 men who were aged ≥66 years and diagnosed with prostate cancer in 1992-2004 were identified. By using Kaplan-Meier methods and Cox proportional hazards models, the primary outcome of hip fracture risk was compared among men who received radical prostatectomy (RP), EBRT, EBRT plus androgen suppression therapy (AST), or AST alone. Age, osteoporosis, race, and other comorbidities were statistically controlled. A secondary outcome was distal forearm fracture as an indicator of the risk of fall-related fracture outside the radiation field.

RESULTS:

After covariates were statistically controlled, the findings showed that EBRT increased the risk of hip fractures by 76% (hazards ratio [HR], 1.76; 95% confidence interval [CI], 1.38-2.40) without increasing the risk of distal forearm fractures (HR, 0.80; 95% CI, 0.56-1.14). Combination therapy with EBRT plus AST increased the risk of hip fracture 145% relative to RP alone (HR, 2.45; 95% CI, 1.88-3.19) and by 40% relative to EBRT alone (HR, 1.40; 95% CI, 1.17-1.68). EBRT plus AST increased the risk of distal forearm fracture by 43% relative to RP alone (HR, 1.43; 95% CI, 0.97-2.10). The number needed to treat to result in 1 hip fracture during a 10-year period was 51 patients (95% CI, 31-103).

CONCLUSIONS:

In men with prostate cancer, pelvic 3-D conformal EBRT was associated with a 76% increased risk of hip fracture. This risk was slightly increased further by the addition of short-course AST to EBRT. This risk associated with EBRT must be site-specific as there was no increase in the risk of fall-related fractures in bones that were outside the radiation field. Cancer 2011. © 2011 American Cancer Society.

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