Proton RT for Prostate Cancer Has Reduced Toxicity, Higher Cost vs Other RT Options

Proton radiation therapy offers some reduced toxicity over intensity-modulated radiotherapy (IMRT) in patients under the age of 65 with prostate cancer, but its cost is nearly twice that of IMRT, according to a new analysis. Stereotactic body radiotherapy (SBRT) had a slightly lower cost than IMRT, with a similar toxicity profile.

IMRT became the most common treatment for localized prostate cancer between 2000 and 2010, and newer radiation techniques have sought to improve on IMRT. “Proton therapy decreases low-dose radiation exposure to uninvolved organs, which potentially translates into lower risks of treatment toxicity and second malignancy,” wrote study authors led by Benjamin D. Smith, MD, of the University of Texas MD Anderson Cancer Center in Houston. “Alternatively, SBRT decreases the number of treatment fractions to only five or fewer, thereby improving convenience and lowering cost.”

Some evidence has suggested that proton radiation costs more, with little added benefit, while SBRT can lower costs while potentially increasing toxicity. Most of that evidence, however, is in older men, though more than 40% of prostate cancer diagnoses occur in those under 65 years. The new study compared the three radiation treatments in a cohort of younger men using a private insurance claims database. The results were published in the Journal of Clinical Oncology.

A total of 693 patients received proton radiation between 2008 and 2015; these were matched to 3,465 IMRT patients. The proton therapy patients had a lower risk of composite urinary toxicity at 2 years, at a rate of 33% compared with 42% (P < .001); this persisted on sensitivity analyses that distinguished between early, late, or procedure-only toxicity. Erectile dysfunction was also less likely with proton therapy, at a rate of 21% at 2 years compared with 28% (P < .001). Bowel toxicity was higher with proton therapy, however, at 20% at 2 years compared with 15% with IMRT (P = .02).

The mean radiation cost was $115,501 with proton therapy, compared with $59,012 with IMRT (P < .001); the cost to the patient with each therapy was $2,269 and $1,714, respectively (P < .001). The 2-year mean complication cost was lower with proton therapy ($1,737 vs $2,730; P = .008), but the mean total healthcare cost was higher ($133,220 vs $79,209; P < .001).

In a comparison between 310 SBRT patients and 3,100 matched IMRT patients, there were no differences in composite urinary, bowel, or erectile dysfunction toxicity rates at 2 years. The mean cost for SBRT was $49,504, compared with $57,244 for IMRT (P < .001); the cost to the patient was $1,015 and $1,560, respectively (P < .001). The mean complication costs and total healthcare costs were similar at 2 years.

“These key findings, coupled with the real-world private insurance cost reported herein, will be useful for patients selecting the most appropriate treatment and for researchers designing cost-effectiveness models to guide treatment decisions in prostate cancer,” the researchers concluded.