A new implant device to prevent edema-associated underdosage in high-dose-rate interstitial brachytherapy of mobile tongue cancer

PURPOSE: Tongue edema is a potential cause of treatment target underdosage in high-dose-rate interstitial brachytherapy (HDR-ISBT) of mobile tongue cancer. To prevent such edema-associated alteration of dosimetry, we developed a special silicon device. In this report we communicate our initial experience with two mobile tongue cancer patients whom we treated using this new device. MATERIAL AND METHODS: The device consists of silicone tubes with a fixed width and scalable length depending on tongue size. These tubes are lined and fixed like a palisade, allowing the device to be used also as a template. The device is placed next to the lateral border of the tongue and on the floor of the mouth. In addition, a vinyl template can be placed on the dorsal tongue surface with both devices combined for implantation guidance. Between June and August 2012, two patients with locally confined tongue cancer were treated. RESULTS: Between June and August 2012, two mobile tongue cancer patients classified as cT2N0M0 were treated with HDR-ISBT using the silicone device. They underwent ISBT as monotherapy with fractional doses of 6.0 Gy up to a total physical dose of 54.0 Gy. The D(90) (CTV) values of both patients were 6.3 Gy and 6.6 Gy and the D(2cc) (mandible) values were 3.4 Gy and 2.6 Gy, respectively. At present, both patients remain without local disease recurrence at 60 and 56 months after ISBT, respectively. CONCLUSIONS: The described silicone device has the potential to prevent underdosage to the treatment target related to tongue edema. It has been shown to be safe and easy to implement.