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Stereotactic Body Radiation Costs Less but Is Associated With More Genitourinary Toxicity vs Intensity-Modulated Radiation Therapy for Prostate Cancer

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Key Points

  • Stereotactic body radiation therapy was associated with lower treatment costs.
  • Stereotactic body radiation therapy was associated with significantly higher rates of genitourinary toxicity at 6, 12, and 24 months and a significantly higher rate of gastrointestinal toxicity at 6 months.

In a retrospective Medicare-based study reported in the Journal of Clinical Oncology, Yu et al found that although stereotactic body radiation therapy is associated with lower treatment costs than intensity-modulated radiation therapy in treatment of prostate cancer, it is also associated with significantly higher rates of genitourinary toxicity.

Study Details

The study used a national sample of Medicare beneficiaries aged ≥ 66 years who received stereotactic body radiation therapy or intensity-modulated radiation therapy as primary treatment for prostate cancer between 2008 and 2011. Each stereotactic body radiation therapy patient (n=1,335) was matched with two intensity-modulated radiation therapy patients (n = 2,670) with similar follow-up of 6, 12, or 24 months. Cost of radiation therapy to the Medicare program was calculated, and genitourinary, gastrointestinal, and other toxicities were assessed for matched patients using Medicare claims.

Increased Genitourinary Toxicity

Mean treatment costs were $13,645 for stereotactic body radiation therapy and $21,023 for intensity-modulated radiation therapy. The overall rate of toxicity was significantly greater with stereotactic body radiation therapy vs intensity-modulated radiation therapy at 6 months (odds ratio [OR] = 1.22, P = .02) but not at 12 or 24 months.

Genitourinary toxicity was significantly greater with stereotactic body radiation therapy vs intensity-modulated radiation therapy at 6 months (15.6% vs 12.6%, OR = 1.29, P = .009), 12 months (27.1% vs 23.2%, OR = 1.23, P = .01), and 24 months (43.9% vs 36.3%, OR = 1.38, P = .001). The increased toxicity was largely attributable to increased urethra- and bladder-related toxicity, with stereotactic body radiation therapy patients having significantly more claims for diagnostic procedures for incontinence and obstruction at 6, 12, and 24 months and more claims for diagnosis of or procedures for urethritis, urethral strictures, and obstruction at 12 and 24 months (P < .003 for all).

Gastrointestinal toxicity was significantly greater with stereotactic body radiation therapy at 6 months (5.8% vs 4.1%, OR = 1.42, P = .02), but not at 12 months (12.2% vs 11.6%) or 24 months (21.2% vs 22.6%). No difference between stereotactic body radiation therapy and intensity-modulated radiation therapy was observed for particular categories of gastrointestinal toxicities or complications.

There was no difference between stereotactic body radiation therapy and intensity-modulated radiation therapy for other (nongenitourinary and nongastrointestinal) toxicities at 6, 12, or 24 months (12.2% vs 14.7% at 24 months).

The investigators concluded, “Although [stereotactic body radiation therapy] was associated with lower treatment costs, there appears to be a greater rate of [genitourinary] toxicity for patients undergoing [stereotactic body radiation therapy] compared with [intensity-modulated radiation therapy], and prospective correlation with randomized trials is needed.”

James B. Yu, MD, of Yale School of Medicine, is the corresponding author for the Journal of Clinical Oncology article.

The study was supported by a grant from the National Cancer Institute, an award from the National Center for Advancing Translational Science, and the National Institutes of Health Roadmap for Medical Research. Dr. Yu receives research funding from 21st Century Oncology. Cary P. Gross, MD, receives research funding from 21st Century Oncology and Medtronic.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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