Maker of proton radiation system that treats tumors raises $200 million

Mevion Medical Systems Inc., a maker of equipment that treats cancerous tumors, has raised $200 million from investors to increase production and expand sales in China.

The 11-year-old Littleton company got most of the cash from HOPU Investments, a Chinese private equity firm, and YuanMing Capital, a Chinese health care investment firm.

Mevion is seeking to take advantage of a large and growing middle class in China that is demanding better medical care. The company also plans to continue marketing to hospitals in the United States, where it has sold seven systems that are now treating patients or being installed.

“We are in the process of ramping up to ship more units,” said Joseph K. Jachinowski, Mevion’s chief executive. “This investment will be used to fund that ramp-up.”

Most cancer patients who need radiation treatment are treated with X-rays, which attack tumors but can also damage healthy tissue. Proton therapy is seen as a better alternative for certain patients, because it does less harm to tissue. But it’s also far more expensive, and insurers don’t cover the treatment for everyone.

Only about a dozen US hospitals, including Massachusetts General Hospital, operate proton treatment systems, because they’re big and heavy and can cost as much as $250 million to buy and install. Mevion’s technology has a much smaller footprint and more affordable price tag of about $25 million.

Mass. General may collect $30,000 for treating a complex cancer with X-ray radiation, but twice that amount for proton therapy, because it’s more expensive to deliver, said Dr. Jay Loeffler, chief of radiation oncology.

“In a perfect world, if the capital costs were the same, proton therapy is something you’d want all patients to receive,” Loeffler said, “but because of the capital costs, it has to be limited in use to only the situations we believe it’s best for.” This includes tumors in children and tumors in adults that are in or near critical body parts like the brain or eyes.

Some hospitals use proton therapy to treat prostate cancer — even when there is no scientific evidence it’s a more effective treatment than traditional radiation, said Dr. Durado Brooks, director of cancer control intervention for the American Cancer Society.

“Because it’s newer doesn’t necessarily mean it’s better’’ for prostate cancer, he said. “At this point we just don’t know.”

Three Mevion systems are treating patients at hospitals in St. Louis, Jacksonville, Fla., and New Brunswick, N.J. Four others are being installed. The company is developing about 20 other orders.

Mevion does not disclose financial details, but Jachinowski said it is on track to collect more than $50 million in revenue this year and to grow 50 percent next year. The company developed its system from technology licensed by the Massachusetts Institute of Technology. It has about 170 employees.