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Proton Therapy Effective, Less Toxic Than Traditional Radiation in HNSCC
Key Takeaways
Proton therapy is a targeted treatment option for head and neck squamous cell carcinoma (HNSCC) that minimizes damage to healthy tissue, a safer alternative to X-ray-based radiation.
Research shows proton therapy can suppress exosome production in HNSCC and enhance anti-tumor immunity.
New dual-energy CT scans and Radflix device improve proton therapy accuracy and the patient experience at Cincinnati Children’s.
Currently, the standard of care for treating head and neck squamous cell carcinoma (HNSCC) is surgery followed by radiation—most commonly X-ray-based, intensity-modulated radiation therapy with or without chemotherapy. However, clinicians and researchers at the Cincinnati Children’s/University of Cincinnati Medical Center Proton Therapy Centeroften treat head and neck cancers more precisely with proton therapy, sparing surrounding tissues and causing fewer side effects than traditional radiation therapy.
Proton therapy, as compared to traditional X-ray-based photon therapy for head and neck cancers, has a dosimetric advantage leading to a potential clinical advantage in many of our patients.
Anthony Mascia, PhD
HNSCC is the sixth most prevalent cancer worldwide. It usually presents at a locally advanced stage, and the tumors often lie in close proximity to critical organs and structures in the head and neck. For this reason, X-ray-based photon therapy is often associated with severe acute and long-term toxic effects, including dysphagia, aspiration, mucositis, soft tissue necrosis and cranial neuropathies.
Proton therapy can precisely deliver an optimal radiation dose to tumors while sparing the surrounding normal tissues. This results in less treatment-related toxicity, as well as a comparable treatment response and disease-free survival.
“Proton therapy, as compared to traditional X-ray-based photon therapy for head and neck cancers, has a dosimetric advantage leading to a potential clinical advantage in many of our patients,” says Anthony Mascia, PhD, executive director of the Proton Therapy Center.
Proton Therapy Reduces Exosome Production, Another Competitive Edge
In addition to typically presenting with tumors close to critical organs, HNSCC is also among the most immunosuppressive cancers. HNSCC cells employ several mechanisms to evade immune surveillance, such as producing tumor-suppressing exosomes. These circulating exosomes can inhibit the effectiveness of cancer therapies, which rely on the ability of effector T and natural killer cells to infiltrate tumors and perform their effector functions.
Proton therapy significantly reduced cancer cells’ production of exosomes by 75%.
Research from a recent study suggests proton therapy suppresses exosome production in HNSCC better than conventional radiation therapy. The study was conducted by lead author Laura Conforti, PhD, professor of internal medicine at the University of Cincinnati College of Medicine, and researchers from the Proton Therapy Center, including Mascia. It found that proton therapy significantly reduced cancer cells’ production of exosomes by 75%.
X-ray-based photon therapy did not reduce exosome production, although the researchers found that exosomes from both proton therapy and X-ray-based photon therapy had similar inhibitory effects on immune cells.
“Exploiting differential impacts on the immune system, like the suppression of exosome production, may underscore an advantage that proton therapy has over X-ray-based photon therapy with respect to anti-tumor immunity and possible combination therapies,” Mascia says.
New Technologies Make Proton Therapy More Accurate, Stress-Free
Cincinnati Children’s continues improving proton therapy for both clinicians and patients with the implementation of two new technologies.
The health system uses an imaging device capable of generating CT scans with two energies, called dual-energy CT scans (DECT). Conventional CT scanners use one energy, generating single-energy CT scans.
In proton therapy, DECT allows advanced planning design and evaluation. This helps Cincinnati Children’s reduce uncertainties in the planning process by up to 50%. In addition to enhancing proton plan dose calculations, DECT can improve contrast in CT imaging and lead to accurate delineation of normal tissues and tumors.
The proton therapy CT scanner also includes:
Artificial intelligence-based contouring that can help identify healthy tissues and expedite proton planning workflow
Respiratory motion management that improves tumor motion mitigation strategies
Functional imaging, like iodine-tracing CT scans, to easily identify healthy and damaged lung tissues
Cincinnati Children’s is making proton therapy treatment easier for patients, too. The health system is the first in Ohio to implement RadFlix, a video-based distraction system that allows patients to watch their favorite movies during treatments. Compatible with all radiation techniques and body sites, this system has been proven to decrease anxiety in children during medical procedures without the need for anesthesia. This approach creates a more comfortable treatment experience, an important part of improving overall outcomes.
