Risk factors and dose-effect relationship for mandibular osteoradionecrosis in oral and oropharyngeal cancer patients.
OBJECTIVE
To analyze risk factors and the dose-effect relationship for osteoradionecrosis (ORN) of the mandible after radiotherapy of oral and oropharyngeal cancers.


METHODS
One-hundred ninety-eight patients with oral (45%) and oropharyngeal cancer (55%) who had received external radiotherapy between 1990 and 2000 were retrospectively reviewed. All patients had a dental evaluation before radiotherapy. The median radiation dose was 60 Gy (range, 16-75 Gy), and the median biologically effective dose for late effects (BED(late)) in bone was 114 Gy(2) (range, 30-167 Gy(2)).


RESULTS
The frequency of ORN was 13 patients (6.6%). Among patients with mandibular surgery, eight had ORN at the surgical site. Among patients without mandibular surgery, five patients had ORN on the molar area of the mandible. The median time to ORN was 22 months (range, 1-69 months). Univariate analysis revealed that mandibular surgery and Co-60 were significant risk factors for ORN (p = 0.01 and 0.04, respectively). In multivariate analysis, mandibular surgery was the most important factor (p = 0.001). High radiation doses over BED 102.6 Gy(2) (conventional dose of 54 Gy at 1.8 Gy/fraction) were also a significant factor for ORN (p = 0.008) and showed a positive dose-effect relationship in logistic regression (p = 0.04) for patients who had undergone mandibular surgery.


CONCLUSIONS
Mandibular surgery was the most significant risk factor for ORN of mandible in oral and oropharyngeal cancers patients. A BED of 102.6 Gy(2) or higher to the mandible also significantly increases the risk of ORN.
Lee
Ik Jae
IJ
Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, Korea.
Koom
Woong Sub
WS
Lee
Chang Geol
CG
Kim
Yong Bae
YB
Yoo
Sei Whan
SW
Keum
Ki Chang
KC
Kim
Gwi Eon
GE
Choi
Eun Chang
EC
Cha
In Ho
IH