ESTRO 2024 - Abstract Book

S1433

Clinical - Head & neck

ESTRO 2024

Radiotherapy: Most patients (75.6%) had intensity modulated radiotherapy (IMRT). Mean treatment dose was 64.5Gy. Mean mandible dose was 42.0 Gy (range 25.81 - 66.0 Gy).

Median interval times to developing ORN from completing radiotherapy, pre-radiotherapy dental extractions and post-radiotherapy dental extractions were 15.0, 8.5 and 4.9 months, respectively.

The site of ORN correlated with the site of dental extractions in 30/41 patients, and with the site of the mandible Dmax +/-2Gy in 11/41 patients.

Average Dmax at the ORN site in patients with extractions at the same site was 56.9Gy. Average Dmax at the ORN site - in a different location to extractions - was 55.0Gy.

Conclusion:

We have described real world data for ORN patients. We have shown a high proportion of our patients had ORN in the site of dental extraction and that in most cases, ORN did not occur at the site of mandible Dmax. This may support a synergistic relationship between dental extractions and radiotherapy in the development of ORN, or could be a result of the extractions taking place in the high risk areas.

Of interest, average Dmax at the site of ORN was similar regardless of whether extractions had occurred there, which may suggest additional factors, such as dental health, are important.

To the best of our knowledge, we are the first to represent the site of ORN with dental extractions, on radiotherapy plans (figure).

Our study was limited by small numbers and missing data regarding the exact site of ORN and dosimetry. We are developing a regional ORN proforma to prospectively collect this data and aim to increase our patient numbers through multi-centre collaboration.

Keywords: Osteoradionecrosis, dentistry, dosimetry