Is Proton-Beam Therapy Facing a Difficult Future?

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Proton-beam therapy is the biggest and most expensive technology on the market. But is it the best? In prostate cancer, there are no data to sufficiently answer that question.

Health-care experts are questioning whether proton-beam therapy is on the verge of an economic bubble—ie, a rapid surge in growth for the industry beyond its intrinsic value, inevitably leading to a drastic drop in earnings for proton centers when the “bubble bursts.” A proton-beam facility can cost upward of $250 million to construct. With 13 proton centers in operation in the United States, 6 more centers set to open by the end of this year, and another 10 planned to open by 2018, a “proton bubble” would spell financial havoc for that sector of the health-care system.

Upswing in Usage Despite High Costs

The suggestion that protons could be effective in treating cancers was made by the American physicist Robert R. Wilson, PhD, in a paper published in 1946.1 The first treatments were performed in the Berkeley Radiation Laboratory in 1954. The first hospital-based proton-beam center in the United States was at the Loma Linda University Medical Center, which began operation in 1990.

Despite the sticker-shock price to build a proton center and the high cost of treatment, proton-beam therapy has surged in use over the past several decades, and much of that growth has been in prostate cancer. The chief selling point for men diagnosed with prostate cancer is the purported precision dosing of proton therapy, which decreases the risk of the two most feared side effects: incontinence and impotence.

Moreover, when a hospital-based proton center incurs a $200-plus million debt, it must amortize that liability with high-volume procedures. With 240,000 new prostate cancers diagnosed each year in the United States, this disease has been the mainstay of the proton therapy industry, accounting for two of every three claims and about 80% of Medicare spending on the procedure.

So while the cost of building a treatment center is high, up until now, proton-beam therapy has presented a lucrative opportunity for those who are willing to make the investment. Proton-beam therapy for prostate cancer is reimbursed at a much higher rate than traditional radiation treatment for the same condition. Medicare pays about $19,000 for a full dose of standard radiation therapy for prostate cancer, but it pays more than $32,000 for proton therapy.

Data Still Lacking

Given the rising costs of U.S. health care, experts across the board agree that it is increasingly important to prove through studies that paying more is associated with better outcomes. Proton therapy has proven beneficial for tumors surrounded by sensitive structures such as the eyes, brain, and spinal cord, where the potential for radiation damage is very high. The procedure also offers a distinct benefit in many childhood cancers due to the high risk of long-term side effects in children who receive standard conformal radiation therapy.

In prostate cancer, however, there are no convincing data demonstrating that proton therapy is superior to intensity-modulated radiotherapy in the curative setting or in mitigating urinary or sexual side effects. Thus, until there are studies that show a distinct benefit, proton-beam therapy rests its case for use in prostate cancer on the theoretical promise that particle beams are better than photons.

In 2012, the California Technology Assessment Forum concluded that while proton-beam therapy provided a net benefit in the treatment of prostate cancer, its comparative benefit to alternate treatment modalities has not been established.2 Its role as a therapeutic option for localized prostate cancer remains uncertain with respect to safety, efficacy, and improvement in patient outcomes.

In a detailed patient guide updated in 2014, the American Cancer Society concluded that use of protons in prostate cancer may theoretically cause less damage to normal tissue surrounding the area of focus, but no current studies demonstrate the advantages of protons over photon therapy.3 The Society stated that comparative studies are necessary to evaluate the outcomes between the different modalities, with identification of the appropriate therapy for different kinds of cancer.

Prostate Model Is Challenged

In December 2014, The Indiana University Proton Therapy Center closed its operations, marking the first time a proton-beam therapy center in the United States has shut down. University executives and an independent review committee attributed the shutdown to the center’s untenable financial losses. Not surprisingly, the losses are largely due to a decrease in the number of prostate cancer patients; insurers are beginning to push back on their coverage of proton-beam therapy until sufficient data prove its efficacy over less expensive modalities.

Indeed, Blue Shield of California, Aetna, and Cigna Corp are no longer covering proton therapy as a treatment option for localized prostate cancer. But there is more afoot in the proton-beam therapy story than the debate over efficacy data. The Indiana University executive review committee also cited changing patterns in the care of prostate cancer patients as a reason for the center’s revenue losses.

For instance, the number of cases diagnosed each year in the United States has fallen. Plus, there has been increased awareness about overtreatment, especially in those men with Gleason scores of 6 or less, giving rise to an increased use of active surveillance as a management technique. Equally important, the majority of cases diagnosed per year are in the low-risk category, and most of those men are being treated with robotic surgery.

The experience of the Indiana University Proton Therapy Center highlights an important phenomenon in health care called “gizmo idolatry,” which has been written about in the literature.4 Simply put, Americans are infatuated with new, expensive, futuristic technology, even if there are no substantial data to support its adoption. It is a “new must be better than old” mentality.

No doubt, proton-beam therapy is the biggest and most expensive technology on the market. But is it the best? In prostate cancer—the business model proton therapy was built on—there are no data to sufficiently answer that question. And until we have the supportive data, every center that opens runs the risk of becoming the next Indiana University Proton Therapy Center. ■


1. Wilson RR: Radiological use of fast protons. Radiology 47:487-491, 1946.

2. Walsh J: Proton beam therapy for prostate cancer: A technology assessment. San Francisco, California Technology Assessment Forum, October 17, 2012. Available at Accessed June 29, 2015.

3. American Cancer Society: Prostate cancer. Last medical review: 12/22/214. Available at Accessed June 29, 2015.

4. Leff B, Finucane TE: Gizmo idolatry. JAMA 299:1830-1832, 2008.