Concurrent Chemoradiation in Oropharyngeal Cancer: Does Omission of 1 or More Cycles of Chemotherapy Diminish Survival or Tumor Control?

Abstract

Materials/Methods: Five patients with OPC who were unable to use bite block or tongue blade underwent computed tomographic simulations with neutral tongue position and stuck-out tongue for planning IMRT (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 using simultaneously integrated boost technique, with mean doses (Dmean) of <26 Gy to the parotid gland, <30 Gy to the submandibular gland, and <36 Gy to the oral cavity (OC). For other organs at risk (OARs), Radiation Therapy Oncology Group (RTOG) recommended dose constraints were applied. Planning was optimized to minimize doses to OARs without compromising coverage of PTVs. Radiation plans with IMRT-N and IMRT-S were compared. Results: IMRT-N and IMRT-S showed equivalent radiation target coverages with sparing OARs, except OC. Dmean of OC was 34.8 1.6 Gy and 30.7 3.0 Gy with IMRT-N and IMRT-S, respectively (PZ.006). OC volume receiving 36 Gy (V36) was 34.1 19.0% using IMRT-N compared to 28.0 15.9% with IMRT-S (PZ.03). Dmean of oral tongue was 39.6 2.7 Gy and 31.7 3.5 Gy in IMRT-N and IMRT-S, respectively (PZ.01). The distance from palate to surface of tongue tend to increase in IMRT-S with 0.9 0.3 cm compared to IMRT-N with 0.1 0.2 cm (PZ.003). Conclusion: In 5 patients with OPC, an IMRT-S significantly reduced radiation dose to oral cavity, specifically oral tongue, compared to IMRT-N without compromising radiation target coverage or other OARs. For the patients with OPC who were unable to use bite block or tongue blade, stuck-out tongue during radiation therapy can provide less radiation dose to OC, which could lead to fewer radiation-related side effects in OC. Author Disclosure: W. Kil: None. C.M. Kulasekere: None. V. Harwalkar: None. J.R. Bugno: None. L.D. Jefferson: None. J.Z. Baskin: None. C.J. Nock: None. R.D. Derrwaldt: None. R. Raju: None. C.L. Hatch: None.