Head and Neck
Nasopharynx
Carcinoma of the nasopharynx is typically treated with radiation therapy alone. Local control rates for T3 lesions range from 60-85 percent. The corresponding rate is 45-70 percent for T4 tumors. Treatment-related complications can be severe because of the high doses received by critical structures surrounding the nasopharynx. These include endocrine complications secondary to hypothalmic or pituitary dysfunction, cranial nerve injuries, and trismus. One can increase the total dose to the primary tumor while shortening the overall treatment time by using the improved properties of proton radiation treatment. This may increase local control of primary tumors and reduce treatment-related side effects seen with conventional radiation. Further, the dose-localization capabilities of proton radiation treatment make it suitable for re-treatment of recurrent tumors.
Oropharynx
Patients treated for locally advanced oropharynx cancer usually receive combined surgery and postoperative photon radiation, or in some selected cases, radiation alone. Unfortunately, with either treatment approach a significantly high incidence of post-treatment morbidity has been reported. Severe treatment-related complications have been reported in up to 50 percent of long-term survivors. Greater doses of radiation are associated with improved levels of control, but unfortunately, this also results in an increased complication rate. This is partly related to the large volume that is taken to a high dose using conventional radiation. Proton treatment increases the total dose to the tumor while decreasing the dose to surrounding normal tissues, thanks to improved dose localization. At Loma Linda University Medical Center, protons are used in conjunction with conventional photon irradiation, with noted improvements in disease control and reduced morbidity. Long-term results have been published.