The era of proton-beam therapy dates to 1954 in Berkeley, when a Cold War invention known as the cyclotron was first used to irradiate a cancer patient's pituitary gland. Since then, the treatment has proved effective against malignancies of the prostate, lung and other organs.

Yet five decades after its first successful use, just six centers nationwide offer the treatment, leading the Wall Street Journal, in a consumer column last year, to refer to proton-beam radiation as "a well-kept secret in the war on cancer."

Size and cost have been the obstacles. A 90,000-square-foot building — bigger than many hospitals — is needed to house a state-of-the-art proton-beam accelerator. And the machines carry price tags of up to $150 million.

But these barriers may be about to topple. Researchers from Lawrence Livermore National Laboratory and UC Davis Cancer Center are working on a subscale prototype of a "miniaturized" proton-beam accelerator. Led by George Caporaso of Livermore's Physics and Advanced Technologies Directorate, the research team aims to deliver a final machine that will be small enough to fit in a typical radiation oncology suite, powerful enough to treat cancer anywhere in the body and priced at about $10 to $15 million. The lab is currently seeking commercial partners to help construct a full-scale model.

"Proton-beam therapy is more targeted, more effective and does less harm to healthy tissues than the radiation we now use in cancer treatment. If we can make it possible for every major cancer center to offer proton therapy, we will impact on cancer worldwide," said Ralph deVere White, associate dean for cancer programs and director of UC Davis Cancer Center.

These centers now offer proton-beam therapy: Loma Linda University Medical Center in Loma Linda, Calif.; Massachusetts General Hospital in Boston; the Midwest Proton Therapy Center in Bloomington, Ind.; MD Anderson Cancer Center in Houston; and Shands Jacksonville Medical Center in Jacksonville, Fla. The UC Davis cyclotron provides proton-beam treatment for eyes only.

While the UC Davis system has the most distinguished pedigree among the proton centers, it is also the smallest. The 70-million-electron-volt protons generated using its 268- pound magnets cannot penetrate more than an inch or two inside the body making it perfect for treating ocular tumors, but too small for most other cancers.

Caporaso expects his compact proton-beam accelerator — although it will be many times smaller than the existing Davis cyclotron — to deliver protons that carry 250 million electron volts of energy apiece, making the machine as powerful as the largest machines now in operation.

Proton-beam therapy is now approved to treat a variety of cancers, but it has been studied most thoroughly as a treatment for prostate cancer. For example, a recent study of more than 1,200 men with localized prostate cancer found that survival rates for those treated with proton-beam therapy matched or exceeded those of men who had conventional treatment — but the proton-beam patients had lower rates of impotence, incontinence and other adverse side effects.

Long history in eyes

The therapy has been used to treat ocular malignancies for more than 30 years; the first eye treatment took place at Harvard's cyclotron in 1975. Three years later, a team of physicians from UC San Francisco and the former Berkeley Radiation Laboratory — renamed the Lawrence Berkeley Laboratory in the late 1950s — began clinical trials of protons and an alternate charged particle, ionized helium, to treat choroidal melanomas. Treatments took place at the Berkeley laboratory using a cyclotron known as the Bevatron.

By the time the Bevatron went offline in 1992, UCSF ophthalmologists had treated more than 2,500 patients and, with Berkeley scientists, had helped to establish the optimal number of treatments and most effective dose per treatment for charged-particle therapy.

That long experience was transferred to UC Davis in 1994, when the UC Davis Proton Eye Treatment Facility was established through the joint efforts of Lawrence Berkeley Laboratory, the UCSF Radiation Oncology Department, the Crocker Nuclear Laboratory at UC Davis and UC Davis Cancer Center. The National Cancer Institute provided additional support.

The UC Davis facility uses a 76-inch cyclotron housed in the Crocker Nuclear Laboratory. The Davis cyclotron has a proud lineage: It was created in the 1960s using components from a 60-inch machine originally built by the Nobel prizewinner who invented the cyclotron, Ernest O. Lawrence.

Sacramento system

Caporaso and his collaborators hope to construct their first full-scale compact proton-beam accelerator at UC Davis Cancer Center, where it would be used to treat not just ocular malignancies but other cancers as well. That would free the Davis cyclotron for full-time use in air-quality, food-safety and space-satellite testing.

"There are a lot of technical challenges remaining. There are no guarantees," Caporaso said. "But progress has been good so far — and we're optimistic."