Decreased radiation doses to tongue with “stick-out” tongue position over neutral tongue position in head and neck cancer patients who refused or could not tolerate an intraoral device (bite-block, tongue blade, or mouthpiece) due to trismus, gag reflex, or discomfort during intensity-modulated radiation therapy

// Whoon Jong Kil 1 , Christina Kulasekere 1 , Ronald Derrwaldt 1 , Jacob Bugno 1 , Craig Hatch 1 1 Cleveland Veterans Affairs Medical Center, Cleveland, Ohio, USA Correspondence to: Whoon Jong Kil, email: whoonkil@gmail.com Keywords: head and neck cancer, IMRT, tongue position, customized immobilization mask, oral cavity Received: May 09, 2016      Accepted: June 01, 2016      Published: July 16, 2016 ABSTRACT Purpose: To assess changes in oral cavity (OC) shapes and radiation doses to tongue with different tongue positions during intensity-modulated radiation therapy (IMRT) in patients with head and neck squamous cell carcinoma (HNSCC) but who refused or did not tolerate an intraoral device (IOD), such as bite block, tongue blade, or mouthpiece. Results: Tongue volume outside of OC was 7.1 ± 3.8 cm 3 (5.4 ± 2.6% of entire OC and 7.8 ± 3.1% of oral tongue) in IMRT-S. D mean of OC was 34.9 ± 8.0 Gy and 31.4 ± 8.7 Gy with IMRT-N and IMRT-S, respectively ( p < 0.001). OC volume receiving ≥ 36 Gy (V36) was 40.6 ± 16.9% with IMRT-N and 33.0 ± 17.0% with IMRT-S ( p < 0.001). D mean of tongue was 38.1 ± 7.9 Gy and 32.8 ± 8.8 Gy in IMRT-N and IMRT-S, respectively ( p < 0.001). V15, V30, and V45 of tongue were significantly lower in IMRT-S (85.3 ± 15.0%, 50.6 ± 16.2%, 24.3 ± 16.0%, respectively) than IMRT-N (94.4 ± 10.6%, 64.7 ± 16.2%, 34.0 ± 18.6%, respectively) (all p < 0.001). Positional offsets of tongue during the course of IMRT-S was –0.1 ± 0.2 cm, 0.01 ± 0.1 cm, and –0.1 ± 0.2 cm (vertical, longitudinal, and lateral, respectively). Materials and Methods: 13 patients with HNSCC underwent CT-simulations both with a neutral tongue position and a stick-out tongue for IMRT planning (IMRT-N and IMRT-S, respectively). Planning objectives were to deliver 70 Gy, 63 Gy, and 56 Gy in 35 fractions to 95% of PTVs. Radiation Therapy Oncology Group (RTOG) recommended dose constraints were applied. Data are presented as mean ± standard deviation and compared using the student t -test. Conclusions: IMRT-S for patients with HNSCC who refused or could not tolerate an IOD has significant decreased radiation dose to the tongue than IMRT-N, which may potentially reduce RT related toxicity in tongue in selected patients.