More than a decade after prostate cancer became the economic driver behind proton beam therapy in the U.S., it still isn't clear that men treated with the technology do better than those who get less costly radiation treatments.

That's why expert groups have recently advised against insurance coverage of proton therapy for prostate cancer - and why some private plans are refusing to pay for it.

The Catch-22 is that this pullback is hampering a clinical trial co-led by the University of Pennsylvania that would finally settle the question of superiority.

The sponsor of the study, the National Cancer Institute, last month wrote a letter urging insurers to cover patients in proton therapy trials, saying "timely completion is critical as more and more centers are beginning to offer proton beam therapy, particularly for prostate cancer."

Indeed, the massive machines continue to proliferate, even as the industry shows signs of financial vulnerability.

Fourteen centers are in operation, and 11 more are in development at up to $200 million per facility, says the National Association for Proton Therapy.

But last month, Indiana University announced the shutdown of its unprofitable center in Bloomington. An expert advisory committee that included Penn radiation oncologist Stephen M. Hahn cited numerous reasons, including the cost to upgrade the center's aging cyclotron, and changing patterns of prostate cancer care that might contribute to a "proton bubble" in the U.S.

"The tension here is that, if centers begin to close, if payors stop paying, we'll never be able to run the studies," said Penn radiation oncologist Justin E. Bekelman, a leader of the clinical trial of proton therapy for prostate cancer.

Theory on protons

In theory, protons have therapeutic advantages. Because these charged particles will stop within a target, they can zap a tumor while sparing nearby healthy tissue. That might reduce the dreaded side effects - incontinence and impotence - of treating the walnut-size prostate gland, which lies deep in the pelvic cavity amid delicate nerves.

The photons of conventional radiation (X-rays) release energy as they enter and exit the body. However, advances have minimized this problem; "intensity-modulated" radiation uses multiple converging beams to better focus the damaging rays.

So which kind of radiation offers the best prostate cancer cure rates and quality of life?

"Some studies show proton therapy is better. Some studies show it might be worse," Bekelman said. "Others show it might be quite similar."

The nation's first proton facility, at Loma Linda University Medical Center in California, boasts that it has treated more than 10,000 prostate cancer patients since opening in 1990. The National Association for Proton Therapy estimates that prostate cancer accounted for 60 percent of the patient volume at proton centers until recent years. (The association's current estimate is 30 percent.)

Yet no one has ever done the gold standard study - randomly assigning many prostate cancer patients to receive either proton or photon radiation therapy, then following them for five years.

That's what Penn and Massachusetts General Hospital began doing two years ago. Their goal is to enroll 400 men.

"At the rate they've been accruing patients, it could take 10 years" to publish results, said Bhadrasain Vikram, chief of National Cancer Institute's radiation oncology branch. "So we're encouraging them to get more institutions" to join the trial.

An obstacle to recruitment is that men who already believe proton therapy is superior don't want to risk being randomized to another treatment.

That belief is fostered by groups like ProtonPals, made up of prostate cancer patients who got proton therapy at the University of Texas MD Anderson Cancer Center.

"We call it a 'radiation vacation' because you don't even know you're being treated," said Drew Cox, 52, a Houston real estate agent who had proton therapy in 2011.

ProtonPals' meetings are ridden with worries about health insurance.

"One of the main topics is how guys had to postpone treatment while they fought their insurance companies," Cox said. "I know one who had to fork over $140,000 and then fight his insurance company to get it back."

Federal payment

Medicare, the federal insurance program, continues to cover proton therapy for prostate cancer. It pays about $32,000 for a treatment course compared with $19,000 for conventional radiation, one study found.

Expert groups, in contrast, have been clamping down.

In April, the Washington State Health Technology Assessment, a state program that influences national payment policies, concluded that scientific evidence justifies coverage of proton therapy only for certain cancers in the eye, the central nervous system, and in children.

In June, the American Society for Radiation Oncology echoed that recommendation. It said prostate cancer proton treatment should only be covered in clinical trials.

Blue Shield of California, UnitedHealthcare, Aetna, and Cigna have recently said they will no longer cover proton therapy for prostate cancer.

Asked whether exceptions would be granted for patients in a clinical trial, Cigna spokesman Roy DeLaMar Jr. e-mailed that the new federal health-care law does not require it.

Bekelman advocates wide adoption of a compromise that Penn has struck with Aetna, Independence Blue Cross, and Horizon Healthcare Services to get coverage for men in the clinical trial: Penn bills for proton therapy at the same rate as latest conventional radiation.

Until the scientific questions are settled, level pricing is a way to "preserve access to proton therapy and renew efforts to conduct crucial comparative research," he wrote in a journal commentary.

Fund-raiser to aid cancer research

The Prostate Cancer Foundation - founded by a survivor, financier Michael Milken - will hold its 12th annual Philadelphia fund-raiser on Tuesday from 4 to 9 p.m. at the Crystal Tea Room in the Wanamaker Building at 100 E. Penn Square. The event has raised millions of dollars to fund prostate cancer research in Philadelphia through the Ben Franklin Young Investigators awards program.

This year, one of those awards will be funded and named in honor of businessman and philanthropist Lewis Katz, a longtime supporter of the foundation. Katz, who co-owned Interstate General Media, parent company of The Inquirer, died in a plane crash in May. The foundation's event will also honor media entrepreneur and philanthropist H.F. "Gerry" Lenfest, now IGM's owner.