CHICAGO ― Proton beam therapy (PBT) combined with selective intra-arterial infusion chemotherapy (IACT) appears to be as safe and effective as surgery in treating locally advanced tongue cancer, researchers reported in a study presented at the 2013 American Society of Clinical Oncology (ASCO) Annual Meeting.

The standard treatment for tongue cancer is surgery; however, patients’ quality of life can be negatively affected. Selective IACT combined with radiotherapy has also been performed to preserve organs and improve treatment results, but late adverse effects including loss of teeth and osteonecrosis of the mandibular bone were extremely problematic. The researchers aimed to investigate PBT, which can deliver a precisely distributed, high dose of radiation to tumors that minimizes exposure to risk organs.

Between February 2009 and February 2013, 45 cases of stage III-IV(M0) tongue cancer were treated by PBT-IACT at Southern TOHOKU Proton Therapy Center in Koriyama, Japan. If surgery was performed, the patients required subtotal or total resection of the tongue.

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Patients initially received two courses of systemic chemotherapy and prophylactic whole neck irradiation. Subsequently, for gross tumor targets, PBT and IACT were administered via the superficial temporal artery by continuous infusion of cisplatin with sodium thiosulphate. For PBT, one or two portals of 210 MeV were arranged in optimal angles to avoid overdosing the risk organ.

Grade 3 or 4 mucositis occurred in 30 patients (66%), and blood/bone marrow toxicity was observed in 24 (53%). No clinically significant adverse side effects were observed.

The median follow-up was 24 months for all patients (range 7-49 months). Using the Kaplan-Meier method, overall survival (OS), progression-free survival (PFS), and local control (LC) rates at 2 years were 88.3%, 77.3%, and 79.9%, respectively. Six of 37 patients experienced recurrence of cervical lymph node metastases (2-year LC, 86.1%) and only two cases had distant metastases (4.4%).

“PBT-IACT appeared to be safe and had a good OS and LC rate for locally advanced tongue cancer. Furthermore, it is not inferior to surgery and can be one of the new effective treatment options for inoperable/locally advanced tongue cancer,” the investigators concluded. However, they also noted that additional improvement of the techniques for intra-arterial infusion and more precise confirmation of the drug distribution are required.