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Prostate cancer: proton radiotherapy versus intensity-modulated radiotherapy toxicity in Medicare beneficiaries

There is no difference between proton radiotherapy ( PRT ) and intensity-modulated radiotherapy ( IMRT ) when comparing the toxicity among Medicare beneficiary patients with prostate cancer at 12 months post-treatment.

Intensity-modulated radiotherapy is the standard form of radiotherapy for the treatment of prostate cancer, accounting for more than 80% of all treatments. Alternative treatments for radiotherapy have emerged, with the most notable being PRT.

Proton radiotherapy treatment has surfaced partly due Medicare reimbursement, which reimburses PRT at a rate of 1.4–2.5 times that of intensity-modulated radiotherapy. Despite its widespread use, the benefits and harms of proton radiotherapy compared with other types of radiotherapy remain unknown.

To determine the long-term effects of proton radiotherapy treatment compared with IMRT treatment, James B. Yu, at Yale University School of Medicine, Department of Therapeutic Radiology, and colleagues performed a retrospective study of all Medicare beneficiaries aged 66 years or older who had received PRT or IMRT for prostate cancer during 2008 and/or 2009.
Each PRT patient was then matched with two IMRT patients with both similar clinical and sociodemographic characteristics to assess the toxicity of each treatment, while the cost of IMRT or PRT treatment was calculated for each patient using the sum of Medicare reimbursements for outpatient and physician claims.

The researchers found that patients who received proton radiotherapy were younger, healthier and from more thriving areas than those who received intensity-modulated radiotherapy. While proton radiotherapy was linked to a statistically significant reduction in genitourinary toxicity at 6 months compared with intensity-modulated radiotherapy, there was no statistically significant difference in gastrointestinal or other toxicities at 6 or 12 months post-treatment.

According to researchers, the relative reimbursement of new medical technologies needs to be considered carefully so that physicians and hospitals do not have a financial incentive to adopt a technology before supporting evidence is available.
Continued longitudinal study of the comparative effectiveness of proton radiotherapy compared with IMRT is needed before widespread application of proton radiotherapy for prostate cancer can be justified.

In an accompanying editorial, Justin E. Bekelman, at Abramson Cancer Center, Perelman Center for Advanced Medicine and Stephen M. Hahn, at the University of Pennsylvania School of Medicine, write that the study has limitations and could lead to misclassifications of the results. Without studies to validate the surrogacy of claims-based endpoints, outcome misclassification could lead to false-negative or false-positive results.

In another accompanying editorial, Theodore S. Lawrence, at University of Michigan, and Mary Feng, at University of Michigan, write that, although it seems unlikely that proton therapy will be superior to IMRT photons for prostate cancer, protons may be superior for tumors in which the elimination of the low-dose regions might decrease normal tissue injury ( eg, lung cancers, when combined with chemotherapy ). ( Xagena )

Source: Journal of the National Cancer Institute, 2013