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Siteman Cancer Center advances proton therapy care

Center to add pencil beam scanning to original proton therapy unit, among other advances

by James GoodwinJune 22, 2021

Siteman Cancer Center

Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine in St. Louis is advancing proton therapy care for patients by adding the latest, most innovative technology to its S. Lee Kling Proton Therapy Center.

The Missouri Health Facilities Review Committee approved Siteman’s application to add pencil beam scanning to its original proton therapy unit at the Kling Center, on the Washington University Medical Campus. The project is scheduled to be completed in 2022. Meanwhile, patients continue to be treated with the center’s second proton therapy unit, which began operating in 2020 and uses pencil beam scanning technology. Pencil beam scanning enables the precise delivery of proton therapy to tumors while avoiding healthy organs nearby. The technology delivers proton therapy in a single, narrow proton beam aimed directly at the tumor and adjusted for intensity. The beam then “paints” the radiation dose on the tumor.

The project also includes the addition of FLASH proton therapy, a form of therapy in which radiation is delivered at an ultra-high dose rate, typically in under one second. FLASH proton therapy, currently available only for research, is an emerging way to deliver radiation therapy. Research has demonstrated that FLASH delivery may effectively kill cancer cells with less toxicity to normal, healthy tissues in the body. The therapy must receive federal Food and Drug Administration (FDA) approval before it can be used to treat patients.

Proton therapy is a focused form of radiation therapy that allows very fine adjustments to the radiation beam, so physicians can precisely target tumors while minimizing damage to surrounding tissue. The therapy is well-suited to patients with solid tumors located near sensitive structures or tissues, such as the eyes, brain or spinal cord. It is particularly beneficial for children, where precise targeting is critical to avoid impacting growing bones or organs. Pediatric patients are treated through Siteman Kids at St. Louis Children’s Hospital.


“Siteman Cancer Center is a national leader in cancer care, and we are committed to providing the very best care to patients,” said Stephanie M. Perkins, MD, director of the S. Lee Kling Proton Therapy Center and an associate professor of radiation oncology and chief of the pediatric radiotherapy service at the School of Medicine. “As the first center in the world with a compact proton design, we desire to always be on the forefront of the advancements and evolution of proton therapy technology. This helps us to achieve our goal of bringing the most effective treatments to our patients with the fewest side effects.”

Proton therapy at Siteman includes the expertise of Washington University radiation oncologists, medical physicists and other subspecialists who work with surgeons and medical oncologists – many of whom also are renowned researchers – to provide multidisciplinary, personalized care.

The Missouri Health Facilities Review Committee serves as the administrator of the Missouri Certificate of Need Law, which is designed to control costs, improve quality and increase access to health-care services across Missouri. The committee approved the Certificate of Need following a finding by committee staff members that Siteman’s application had met all required criteria and that there was need for the proton therapy upgrade.

When the proton therapy center opened in 2013, it was the first globally to feature a compact proton beam accelerator. Such a system requires less physical space and can be built at a fraction of the cost of traditional systems. Washington University radiation oncologists and physicists at Siteman helped evaluate the technology, called the Mevion S250® Proton Beam Therapy System, and developed the patient protocols and quality standards for its use.

The proton therapy center, the only one in Missouri and within a 240-mile radius of St. Louis, is named in honor of the late S. Lee Kling, a former chairman of The Foundation for Barnes-Jewish Hospital’s board of directors. He wanted residents of the region to have access to the leading-edge technology without having to travel far, so he and his family provided financial support to help build the proton center.

Other specialized radiation therapy technologies available at Siteman include MRI-guided radiation therapy, CT-guided radiation therapy, Gamma Knife radiosurgery and stereotactic body radiation therapy. All are forms of external beam radiation therapy because the treatments are administered from outside the body. Another type of radiation therapy, brachytherapy, involves implanting “seeds” of radioactive materials next to the tumor. Washington University radiation oncologists at Siteman also are using new systemic forms of radiation therapy for a variety of cancers, including metastatic prostate cancer. These treatments involve using a targeted radioactive drug that can be given by mouth or through a vein. The drug then finds its way and attaches to cancer cells. The type of radiation therapy used in a patient’s treatment depends on where cancer cells are located.

Washington University School of Medicine’s 1,500 faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is a leader in medical research, teaching and patient care, consistently ranking among the top medical schools in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.

Siteman Cancer Center, ranked among the top cancer treatment centers by U.S. News & World Report, also is one of only a few cancer centers to receive the highest rating of the National Cancer Institute (NCI) – “exceptional.” Comprising the cancer research, prevention and treatment programs of Barnes-Jewish Hospital and Washington University School of Medicine in St. Louis, Siteman treats adults at six locations and partners with St. Louis Children’s Hospital in the treatment of pediatric patients. Siteman is Missouri’s only NCI-designated Comprehensive Cancer Center and the state’s only member of the National Comprehensive Cancer Network. Through the Siteman Cancer Network, Siteman Cancer Center works with regional medical centers to improve the health and well-being of people and communities by expanding access to cancer prevention and control strategies, clinical studies and genomic and genetic testing, all aimed at reducing the burden of cancer.