Osteoradionecrosis rate in oropharynx cancer treated with dose volume histogram based constraints

Radiother Oncol. 2022 Nov:176:215-221. doi: 10.1016/j.radonc.2022.10.011. Epub 2022 Oct 15.


Objectives: Mandibular dose constraints are designed to limit high dose to small volumes to avoid osteoradionecrosis (ORN). Based upon a published experience, intermediate-dose constraints were introduced but have not been independently validated. We hypothesize that these constraints lower ORN rate without compromising other organs at risk (OAR).

Methods: Oropharyngeal cancer patients treated with standard fractionation adjuvant/definitive VMAT from 01/2014-08/2020 were included. In 09/2017, mandibular dose constraint was changed from historical constraint (HC) of D 0.1 cc < 70 Gy to modified constraints (MC) of V 44 Gy < 42%, V 58 Gy < 25%, D 0.5 cc < 70 Gy. OAR dosimetric changes and ORN development were evaluated. Regression modelling predicted long-term ORN cases in MC group.

Results: There were 174 patients, 71 in MC group. Seven cases of ORN in HC group at a median follow up (FU) of 39 months and 1 case of ORN in MC group at a median FU of 11 months were observed. More patients in the MC group met V 44 Gy (87% vs 62%, p < 0.01) and V 58 Gy constraints (92% vs 73%, p < 0.01). Mean doses to OARs did not rise. Mandible V 44 Gy and V 58 Gy were significantly associated with ORN (p < 0.01 and p = 0.03, respectively) across all patients. In the HC group, V 44 Gy was independently associated with ORN (p = 0.01). To account for shorter FU in MC group, logistic regression of ORN based on V 44 Gy in HC patients was performed. This predicts 3.2 ORN cases in the MC group (95% CI: 0.00-6.4).

Conclusion: Achieving V 44 Gy and V 58 Gy was successful in 87% of cases without sacrificing target coverage or OARs and resulted in non-significant ORN decrease.

Keywords: Dose constraints; Mandibular osteoradionecrosis; Organs at risk; Oropharynx cancer.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Dose Fractionation, Radiation
  • Humans
  • Oropharyngeal Neoplasms* / radiotherapy
  • Osteoradionecrosis* / etiology
  • Radiometry
  • Radiotherapy Dosage
  • Retrospective Studies