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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 D90 (CTV) values of both patients were 6.3 Gy and 6.6 Gy and the D2cc (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.

We initiated the first multi-institutional prospective study of accelerated partial breast irradiation for early breast cancer in Japan. Our early clinical results showed that the treatment methods were technically reproducible between institutions and showed excellent disease control at a median follow-up of 26 months in our previous report. At present, total 46 patients from six institutions underwent the treatment regimen from October 2009 to December 2011, and the median follow-up time was 60 months (range, 57-67 months). In 46 patients, we experienced one patient who had rib fracture as a late complication. The dose-volume histogram (DVH) result of this patient was analyzed. The D0.01cc, D0.1cc, and D1cc values of the patient were 913, 817, and 664 cGy per fraction, respectively. These values were the highest values in 46 patients. The average D0.01cc, D0.1cc, and D1cc values of the other 45 patients were 546, 500, and 419, respectively, cGy per fraction. From this result, DVH values showing high-dose irradiated volume (D0.01cc, D0.1cc, and D1cc) seem to be a good predictive factor of rib fracture for accelerated partial breast irradiation. However, further investigation is necessary because of the small number of patients investigated.

Purpose : We report our study on two patients to highlight the risk of underdosage of the clinical target volume (CTV) due to edema during high-dose-rate interstitial brachytherapy (HDR-ISBT) of mobile tongue cancer. Material and methods : To treat the lateral side of the CTV, flexible applicator tubes were implanted on the mouth floor. Two-dimensional planning was performed using X-ray images for Case 1, and three-dimensional (3D) planning was performed using computed tomography (CT) for Case 2. Prescribed doses for both cases were 54 Gy in nine fractions. Case reports : Case 1 was treated for cancer of the right lateral border of the tongue in 2005. Tongue edema occurred after implantation, and part of the lateral border of the tongue protruded between the applicator tubes. Acute mucosal reaction abated in the protruded area earlier than in the other parts of the CTV. In this case, the tumor recurred in this area 5 months after the treatment. Case 2 was treated for cancer of the left lateral border of the tongue. Because tongue edema occurred in this case also, plastic splints were inserted between the applicator tubes to push the edematous region into the irradiated area. The mucosal surface of the CTV was covered by the 70% isodose, and 100% isodose line for before and after splint insertion. Local control of the tumor was achieved 4 years after treatment. Discussion and conclusions : To ensure sufficient target coverage, 3D image-based planning using CT should be performed, followed by re-planning using repeated CT as needed. Also, the development of devices to prevent protrusion of the edematous tissue outside the target area will help to ensure the full dosing of CTV.

Purpose: To compare the outcome of our facility with another about the shortened schedule (60 Gy in 10 fractions to 54 Gy in 9 fractions) of high-dose-rate interstitial brachytherapy (HDR ISBT) for mobile tongue cancer. Material and methods: Eighteen patients were treated with HDR ISBT as a monotherapy in dose reduction schedule with some unique technique to determine the border of tumor accuracy (lugol’s staining and metal marker), and to minimize adverse effect (lead-lined silicon block) at our facility. Results: The 2-year local and regional control rates and cause-specific survival rate were 82%, 80%, and 83% and moderate to severe late complications occurred in five patients (28%), which were almost the same treatment results achieved by another facility. Conclusions: We recommend 54 Gy in 9 fractions over 7 days as a feasible treatment to reduce patient discomfort in mobile tongue cancer patients. J Contemp Brachytherapy 2014; 6, 1: 10–14 DOI: 10.5114/jcb.2014.40726