The University of Michigan Health System and an alliance of other healthcare providers from across the state are teaming up to bring what they call the world's most expensive piece of medical technology to Michigan.

A proton therapy facility with a $160-million price tag will eventually be used for cancer treatment in the state, but so far it hasn't been proven to be any more effective than traditional radiation therapy.

For Robert Kelch, the University's executive vice president for medical affairs, the lack of scientific proof isn't a problem.

"It's very, very appealing from a theoretical standpoint," Kelch said. "There isn't data available today that proves the effectiveness of the therapy."

The therapy is different from traditional radiation treatment because it uses protons, instead of light particles called photons, to treat cancer.

Theodore Lawrence, chair of the UMHS department of radiation oncology, said the new technology would probably reduce the side effects associated with existing radiation treatments.

Proton therapy uses proton beams that can be aimed more accurately than photon beams and so should cause less damage to the tissue surrounding a cancerous tumor, Lawrence said.

The machine used to aim the proton beam, called a gantry, can weigh up to 100 tons, which Lawrence said partially explains why an entirely new building is needed to house the equipment. He cited protection from radiation as another reason for the $160 million facility that could take more than two years to construct.

The price of a comparable photon radiation facility would cost about $20 million and can fit in a normal hospital room.

Kelch said the project's high cost was one reason to collaborate with other health systems to establish the proton therapy facility. He said the consortium hasn't settled on a final business plan, but the six institutions shared the costs of preliminary research and other early expenses equally.

The institutions are still negotiating a location for the new facility, but Kelch said it would probably be in the southeastern part of the state because that's where most Michigan residents live.

Lawrence said it was also important to diffuse the costs so that hospital administrators weren't in such a hurry to recoup their losses. He said an individual hospital might be tempted to use the more expensive new equipment in situations when photon therapy would be adequate, passing along the expenses of the equipment to cancer patients.

"I think it's very important that we do this for the people of Michigan and not for any one institution," Lawrence said.

Hundreds of people could potentially benefit from the proton therapy each year, but Lawrence said it was too early to make specific predictions. He added that most of the patients would probably be children because it's especially important to reduce their exposure to radiation.

As doctors begin to use the technology more, Lawrence said, they'll get a better idea about the types of tumors it would be appropriate for and if it actually provided any benefit over traditional photon therapy. He said he hopes they will soon be able to prove that proton therapy is more effective that photon therapy for certain tumors.

"With the thousands of patients who have been treated, I wish someone had done this study already," he said.