Proton Flash Radiotherapy Trial Demonstrates Pain Reduction in Thoracic Bone Metastases

In a significant advancement in cancer treatment, Siemens Healthineers has unveiled results from the FAST-02 clinical trial, demonstrating the efficacy of proton Flash radiotherapy in alleviating pain from thoracic bone metastases. This study, an extension of prior research titled FAST-01, confirms that proton Flash therapy is not only feasible but also effective in providing substantial pain relief.

The trial, conducted at the Cincinnati Children’s/University of Cincinnati Proton Therapy Center, was led by John Perentesis, MD, alongside Emily Daugherty, MD, and focused on patients with metastases in the ribs, clavicle, scapula, and sternum. The therapy delivers treatment at ultra-high dose rates within one second, a significant reduction in duration compared to conventional radiation therapy, and has previously shown promise in reducing damage to healthy tissues while maintaining effective tumor control.

A cohort of 10 adult participants received a single 8 Gy fraction at a dose rate exceeding 40 Gy/second. Pain relief was assessed using scores reported by participants one to three months post-treatment. Of the eight patients with three-month data, 75% reported complete pain relief, while the remaining 25% experienced partial pain reduction. Importantly, no severe adverse effects were observed, indicating the safety of the therapy even when near critical organs such as the lungs and heart.

"The significance of FAST-02 lies in our treatment sites being bone metastases within the thorax, meaning proximity to the lungs, heart and spinal cord," remarked Dr. Daugherty. Despite the proximity to these sensitive organs, no cardiac or pulmonary toxicities were reported.

Ricky Sharma, MD, PhD, head of clinical strategy at Varian, highlighted the next steps, stressing the need for larger and multi-center clinical trials to explore this treatment across various cancer types. These forthcoming studies aim to further demonstrate the transformative potential of proton Flash therapy in clinical settings.

Central to this clinical success was the adaptation of Varian’s ProBeam proton therapy system and enhancement in the Eclipse treatment planning system to support ultra-high-dose-rate delivery. The findings from FAST-02 set the stage for future research, guiding the ongoing development and potential clinical integration of Flash technology.