First All Pencil-Beam Proton Center in the United States Designed to Treat Wide Range of Tumors

The first proton therapy center in the United States designed to treat patients exclusively with pencil-beam scanning is reporting excellent results in delivering cancer treatment since opening for patient care in February 2014.

Carl Rossi, MD, medical director of the Scripps Proton Therapy Center (San Diego, CA, USA) offered the assessment in San Francisco (CA, USA), where the American Society for Radiation Oncology (ASTRO) held its US annual meeting September 14–17, 2014. Dr. Rossi reported that physicians at the Scripps Proton Therapy Center have treated a range of tumor sites in its first seven months that previous new proton centers have taken a year or two to accomplish. A 20-year veteran of proton therapy, Dr. Rossi also noted that the new center is offering accurate radiation delivery and the capability to treat larger tumor fields than ever before possible, while also providing greater effectiveness with on-time patient treatments.

Earlier proton centers typically were established with a focus on treating comparatively uncomplicated cases, such as prostate cancer, and then over time, expanded. However, Scripps has branched out more quickly, due to the capabilities of pencil-beam scanning and physicians’ readiness to address patients’ inquiries. Tumor sites treated at the Scripps center since February 2014, include lung, brain, spinal column, base of skull, head and neck (e.g., oropharynx, salivary gland), central nervous system, pancreas, rectum, esophagus, breast (male and female), testis, inter-abdominal lymphoid tissue, thymus gland, and bone. The center has also delivered a number of re-treatments in areas where patients had earlier radiation therapy (an application where protons are particularly attractive, because less healthy tissue is exposed to radiation).

The center’s ProBeam pencil-beam technology, developed by Varian Medical Systems (Palo Alto, CA, USA), enables clinicians to be a great deal more exact in where they deliver the radiation dose compared to earlier passive scatter technology. The system also allows clinicians to fluctuate the radiation dose within the tumor target, which previously was not possible. It also creates the ability to treat larger and more irregularly shaped fields (long, narrow fields up to 40-cm long). Having the ability to treat a single, larger field is far less cumbersome and time consuming than transitioning to treat multiple tumor fields.

By exclusively using pencil-beam scanning, every patient’s treatment plan at Scripps comes in the form of a data file. This means there is no need to install physical devices outside of the treatment nozzle for each patient, as is needed with passive scatter technology, which is most widely used today. Therefore, when a Scripps proton patient needs to be moved from one treatment room to another, the move can be made easily and quickly, frequently in a matter of minutes.

As a member of the Proton Collaborative Group (PCG), Scripps Health is participating in multi-institutional research studies to help optimize proton therapy. Currently, Scripps is part of a PCG registry trial to gather clinical outcomes data from all of its patients, regardless of diagnosis, and plans to expand into tumor-specific research that will explore areas such as hypofractionation. Scripps also plans to be involved in randomized research trials comparing proton and X-ray radiotherapy.

Scripps Proton Therapy Center offers sophisticated technology needed for precise tumor targeting, including computed tomography (CT) and positron emission tomography (PET)-CT scanners and a magnetic resonance imaging (MRI) machine. Dr. Rossi stated that this eliminates the need for patients to carry their immobilization devices to another location, or to compete with other departments in the health system for access to this technology.

Dr. Rossi noted the advanced imaging tools enable greater tumor visibility, which leads to better treatment plans. “For example, with a prostate patient, I may be able to see within the prostate gland and identify an area I want to hit harder. With head and neck patients, we can differentiate the lymph nodes more easily,” he said.

Furthermore, having this equipment on site enables clinicians to quickly and easily order scans to verify patient anatomy and to look at tumor regression during treatment, and to rapidly adapt the radiation fields to changes in tumor configuration.

Related Links:
Scripps Proton Therapy Center
Varian Medical Systems