Early Quality of Life Better with Proton-beam Therapy, but Late Effects Similar to Other Treatment Modalities for Prostate Cancer


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Differing patterns of patient-reported quality of life for three-dimensional (3D) conformal radiotherapy, intensity-modulated radiation therapy, and proton-beam therapy were reported in a nonrandomized comparison of three modern cohorts of patients with prostate cancer. The study was presented at the 54th Annual Meeting of the American Society for Radiation Oncology (ASTRO) in Boston.

At the first follow-up 2 to 3 months following therapy, patients treated with proton-beam therapy reported minimal bowel problems; however, patients treated with 3D conformal radiotherapy and intensity-modulated radiotherapy reported modest yet significant problems with bowel function. At 2 years, all three techniques were associated with similar modest but significant bowel problems.

Quality-of-life decrements in the urinary obstruction domain were observed for all three techniques at the early assessment, but this was deemed clinically meaningful only in intensity-modulated radiotherapy–treated patients (though 3D conformal radiotherapy patients received lower total doses of radiation). Sexual function domain scores were lower with all three techniques at 2 years, but these changes were not deemed clinically meaningful.

Prospective Trial Needed

“These distinct patterns of treatment-related [quality of life] suggest that [proton-beam therapy] may be associated with fewer immediate side effects. Given the inherent limitations of any retrospective study, a prospective randomized controlled trial to investigate these differences will provide the most rigorous and valid comparison of these advanced technologies,” said lead author Phillip J. Gray, MD, a resident in the Harvard Radiation Oncology Program in Boston.

All three technologies are proven means of delivering high-dose radiation for localized prostate cancer with acceptable rates of acute and late toxicities. Intensity-modulated radiotherapy has largely overtaken 3D conformal radiotherapy as the technique of choice for prostate cancer treatment in the United States, but use of proton-beam therapy is on the rise, with 10 centers currently operating and at least 17 more planned. Proton-beam therapy is more expensive than the other techniques, and improved quality of life may be a consideration in selecting therapy, Dr. Gray said.

Patients in this study were treated with radiation therapy according to the standard techniques of the participating hospitals. Quality-of-life data were collected prospectively using the Expanded Prostate Cancer Index Composite (EPIC) for 153 patients treated with intensity-modulated radiotherapy. The Prostate Cancer Symptoms Index (PCSI) instrument was used to collect quality-of-life data on 123 patients treated with 3D conformal radiotherapy monotherapy and 94 patients treated with proton-beam therapy.

Mean scores at baseline, at first follow-up, and at 24 months were compared using paired t-tests. Clinically meaningful differences in quality-of-life scores were defined as those exceeding half the baseline standard deviation. Dr. Gray explained that score changes exceeding that threshold would be clinically evident to physicians.

A randomized, prospective phase III trial has recently been opened to compare intensity-modulated radiotherapy and proton-beam therapy for patients with localized prostate cancer. The study is led by Jason A. Efstathiou, MD, DPhil, and Justin Bekelman, MD, in partnership between the Massachusetts General Hospital and the University of Pennsylvania. Several other proton centers are expected to join the trial next year.

Medicare Analysis

A second study presented at the same session called into question the growing use of proton-beam therapy. That study was based on the Medicare Chronic Condition Warehouse database, which includes 100% of U.S. Medicare claims for patients with certain chronic conditions, including prostate cancer. The investigators compared data for proton-beam therapy vs intensity-modulated radiotherapy and found minimal differences in toxicity between the two techniques, with a much higher cost for proton-beam therapy.

“[Proton-beam therapy] is an emerging treatment for men with prostate cancer, yet it is much more expensive than the standard of care, [intensity-modulated radiotherapy],” said James Yu, MD, Yale University School of Medicine, New Haven, Connecticut. “The results of our study suggest that we need a prospective large study comparing radiation techniques to justify widespread use of [proton-beam therapy] for prostate cancer,” he said.

The database included 27,647 men, aged 66 to 94 years, treated with intensity-modulated radiotherapy or proton-beam therapy for prostate cancer in 2008–2009; 2% received proton-beam therapy, and 98% were treated with intensity-modulated radiotherapy.

Patients treated with proton-beam therapy were younger, healthier, and from geographic areas of higher socioeconomic status than patients undergoing intensity-modulated radiotherapy. Dr. Yu noted that patients receiving proton-beam therapy often traveled great distances to receive treatment, “with 15% traveling 500 miles or more.”

The median amount of reimbursement per patient by Medicare was $32,428 for proton-beam therapy and $18,575 for intensity-modulated radiotherapy, a difference of 57%, Dr. Yu said.

Proton-beam therapy was associated with a significant reduction in urinary toxicity at 6 months vs intensity-modulated radiotherapy (5.9% vs 9.5%), but by 1 year there was no difference between groups for this toxicity. No significant differences between the two groups in gastrointestinal or other toxicity were reported at 6 months and 1 year.

Limitations of this study noted at the ASTRO meeting include the fact that it is a claims-based analysis with no staging information and no data on the extent or field of radiation. ■

Disclosure:Drs. Gray and Yu reported no potential conflicts of interest.

References

1. Gray PJ, Paly JJ, Yeap B, et al: Patient-reported quality of life in prostate cancer patients treated with 3D conformal intensity modulated or proton beam radiation therapy. 54th ASTRO Annual Meeting. Abstract 30. Presented October 28, 2012.

2. Yu JB, Soulos PR, Herrin J, et al: Proton radiotherapy for prostate cancer in the Medicare population: Patterns of care and comparison of early toxicity with intensity modulated radiation therapy. 54th ASTRO Annual Meeting. Abstract 31. Presented October 28, 2012.



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