Conformal dose patterns for a patient with tonsillar cancer demonstrating radiation exposure to the head and neck for (A) standard radiation therapy and (B) proton therapy.
Radiation-oncologists at Penn Medicine are using proton therapy (PT) as an option for the treatment of cancers of the head and neck. The prevailing complication for standard radiation treatment of advanced head and neck cancers is the close proximity of critical organs that are highly sensitive to radiation, including the brain, brainstem, spine, salivary glands and swallowing structures.
Classic radiation treatment protocols must consider with great care the adequate treatment of a cancer while minimizing damage to normal organs nearby. This is important for several reasons. In its application to the head and neck, radiation therapy can cause loss of sensation, dry mouth due to impaired saliva production, neurological damage and the risk of secondary cancers.
At the same time, efforts to minimize exposure to structures outside the cancer must avoid inadequate delivery of radiation doses that could increase the risk of cancer recurrence. The physical properties of proton beams may offer unique advantages for the treatment of head and neck cancers. Among the most important of these is the rapid dose fall-off at the distal edge of the target (referred to as the Bragg-Peak effect), a characteristic that allows for significant reductions in radiation dose to normal organs, improved dose homogeneity and the potential for dose escalation.
This physical feature of proton beams allows delivery of high doses to the cancer with much greater precision. Dosimetric studies of head and neck cancer patients comparing intensity-modulated forms of standard radiation therapy (IMRT) to proton therapy (IMPT) have demonstrated that critical organs were optimally spared with IMPT, with lower estimated secondary cancer risks as a result of lower radiation dose received by normal tissue.1
At the Roberts Proton Therapy Center at Penn Medicine, patients with head and neck cancers are being treated in clinical studies to confirm whether the dosimetric advantages of proton therapy shown in previous studies will translate to gains in treatment outcome and patient-reported improvements in side effects and quality of life. Many patients with head and neck cancers are being treated with a technique known as pencil beam scanning proton therapy at the Roberts Center, in collaboration with the Departments of Otorhinolaryngology-Head and Neck Surgery and Medical Oncology. Patients for whom the initial treatment of the cancer requires surgery are treated initially with a minimally-invasive approach via TransOral Robotic Surgery (TORS). For patients who then require additional treatment, proton therapy offers a promising option.
If surgery is not feasible or recommended, proton therapy is often combined with chemotherapy with curative intent. Pencil beam scanning proton therapy is also being used at Penn for the treatment of head and neck cancers involving the base of the skull. [1] Treatment of tumors with conventional radiation at this particular site has traditionally been limited by an inability to deliver an adequate dose in the absence of the potentially damaging effects of radiation on normal critical structures in the brain and optic apparatus. Pencil beam scanning allows for more precise delivery of radiation to the tumor while avoiding these critical structures.
Case Study
Mr. V, a 54-year-old man, was referred to an otorhinolaryngologist at Penn Medicine after presenting to his personal physician with a mass in his left neck.
At Penn, a CT scan found a 3.3 cm lesion at the left lingual tonsil. A subsequent needle biopsy determined that the mass was an HPV-positive tonsil cancer. Mr. V was scheduled for a TransOral Robotic Surgery (TORS) procedure to remove the lesion (T2 stage), followed by a left neck dissection, with the latter showing multiple involved nodes
Considered a good candidate for proton therapy, Mr. V was treated post-operatively with PT to limit morbidity associated with radiation therapy. His course of treatment and recovery were unremarkable, and he did well throughout his radiation therapy with protons, experiencing only mild and transient changes in taste (with return to normal by 6 weeks) and no weight loss as a result of treatment. He returned to work soon afterward, and remains cancer free at one year post-surgery.
Access
Penn Radiation Oncology
Perelman Center for Advanced Medicine
Concourse Level
3400 Civic Center Boulevard
Philadelphia, PA 19104
Otorhinolaryngology – Head and Neck Surgery
Hospital of the University of Pennsylvania
5 Silverstein
3400 Spruce Street
Philadelphia, PA 19104
Published on: May 1, 2017
References
1. Ahn PH, Lukens JN, Teo BK, Kirk M, Lin A. The use of proton therapy in the treatment of head and neck cancers. Cancer J. 2014 Nov-Dec;20(6):421-6.
About Penn Radiation Oncology
Among the largest and most respected programs in the world, Penn Radiation Oncology offers a variety of innovative treatment options to patients with cancer. In addition, as a national leader in basic science, translational research and clinical trials, Penn Radiation Oncology offers patients access to the latest treatment options––including proton therapy––before they are widely available elsewhere.
Performing Proton Therapy, Oncology Services and Surgery for Head and Neck Cancers
Penn Faculty Team
Helene Blum Assistant Professor
Chief, Head and Neck Service
Medical Director, Roberts Proton Therapy Center
Associate Professor of Radiation Oncology at the Hospital of the University of Pennsylvania
Assistant Professor of Radiation Oncology at the Hospital of the University of Pennsylvania
Director, Network Development Program
Professor of Clinical Radiation Oncology
Assistant Professor of Radiation Oncology at the Veteran's Administration Medical Center
Assistant Professor of Medicine at the Hospital of the University of Pennsylvania
Assistant Professor of Medicine at the Hospital of the University of Pennsylvania and the Veteran's Administration Medical Center
Assistant Professor of Clinical Medicine
Associate Director of Clinical Research, Abramson Cancer Center
Director, Hematology/Oncology Fellowship Program
Professor of Medicine at the Hospital of the University of Pennsylvania
Assistant Professor of Clinical Medicine
Director, Microvascular Surgery and Education
Assistant Professor of Clinical Otorhinolaryngology: Head and Neck Surgery
Director, Facial Plastic Reconstruction
Director, Microvascular Lab
Patient Safety Officer
Professor of Otorhinolaryngology: Head and Neck Surgery at the Hospital of the University of Pennsylvania
Co-Director, Cranial Base Center
Director, Head & Neck Surgery, Pennsylvania Hospital
Associate Professor of Otorhinolaryngology: Head and Neck Surgery at the Hospital of the University of Pennsylvania and the Pennsylvania Hospital
Associate Vice President, Physician Network Development
Chair, Department of Otorhinolaryngology - Head and Neck Surgery
Co-Director, Head and Neck Cancer Center
Gabriel Tucker Professor of Otorhinolaryngology: Head and Neck Surgery
Professor of Otorhinolaryngology in Neurosurgery
Professor of Radiation Oncology
Associate Professor of Clinical Otorhinolaryngology: Head and Neck Surgery
Assistant Professor of Otorhinolaryngology: Head and Neck Surgery
Co-Director, Center for Head and Neck Cancer
Director, Head and Neck Oncology Fellowship
Director, Head and Neck Surgery Division and Head and Neck Surgery Clinic
Vice Chairman, Department of Otorhinolaryngology: Head and Neck Surgery
Professor of Otorhinolaryngology: Head and Neck Surgery at the Hospital of the University of Pennsylvania