Tongue-out versus tongue-in position during intensity-modulated radiotherapy for base of tongue cancer: Clinical implications for minimizing post-radiotherapy swallowing dysfunction.

BACKGROUND: The purpose of this study was to assess whether different tongue positions change the radiation doses to swallowing organs at risks: the pharyngeal constrictor, oral cavity, and larynx during intensity-modulated radiotherapy (IMRT) for base of tongue (BOT) cancer. METHODS: IMRT plans with Tongue-out (IMRT-TO) and tongue-in position (IMRT-TI) was compared in 3 cases. RESULTS: Distance from BOT to pharyngeal constrictor was increased to 1.8 ± 0.8 cm with IMRT-TO from 0.9 ± 0.6 cm with IMRT-TI (P < .01). Compared to IMRT-TI, IMRT-TO significantly decreased the radiation dose to the anterior oral cavity, oral tongue, superior pharyngeal constrictor, middle pharyngeal constrictor, and supraglottic larynx (all P ≤ .04). IMRT-TO also had a smaller volume irradiated than IMRT-TI to the anterior oral cavity and the oral tongue receiving ≥30 Gy (V30) and V35, and superior pharyngeal constrictor and middle pharyngeal constrictor for V55 and V65 (all P ≤ .04). CONCLUSION: Dosimetric advantage with IMRT-TO over IMRT-TI may potentially reduce post-IMRT swallowing dysfunction in selected patients with BOT cancer.

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.

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 cm3 (5.4 ± 2.6% of entire OC and 7.8 ± 3.1% of oral tongue) in IMRT-S. Dmean 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). Dmean 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.