ESTRO 2024 - Abstract Book

S1236

Clinical - Head & neck

ESTRO 2024

Analyzing the change in maximum dose of PTV70Gy over treatment sessions, the adaptive group showed an average 1.4% lower maximum dose compared to the non-adaptive group. For each additional session in the adaptive group, the maximum dose of PTV70Gy increased by approximately 0.02%, with no significant interaction between session and group. A dosimetric analysis of select organs at risk (OARs) revealed that adaptive treatment resulted in a reduction in the maximum dose for the spine and brainstem by 1.2 Gy and 3.9 Gy, respectively. Other OARs showed numerical benefits with adaptation, although these did not reach statistical significance. Several OARs demonstrated a statistically significant change per additional session. Throughout the treatment course, significant daily volume reductions were observed for PTV60, PTV56, left parotid, and right parotid by 0.28cc, 0.25cc, 0.15cc, and 0.12cc, respectively. While a reduction in PTV70 volume was also observed, it did not reach statistical significance.

In terms of treatment outcomes, at a median follow-up of 14.1 months, the local control rate was 95.5%. Patients experienced generally favorable toxicity profiles, with no instances of grade 4 or 5 toxicities reported.

Conclusion:

In conclusion, the study underscores the potential of daily AI-assisted adaptive radiotherapy to improve precision and dosimetric outcomes in the treatment of LAHN. The findings demonstrate significant benefits in target coverage and reduced high-dose hot spots, enhancing the therapeutic ratio. Despite certain limitations, such as the retrospective design and variable compliance with follow-up imaging, the results point towards a positive impact on clinical outcomes. Further investigations are warranted to identify specific patient cohorts that may derive the greatest advantage from daily online adaptive radiotherapy. This innovative approach holds promise for enhancing the management of a complex and challenging disease, ultimately improving the prospects of head and neck cancer patients. Further study into reduce-margin adaptive radiotherapy and planned reduction in high-dose PTV volumes throughout the treatment course may further improve outcomes.

Keywords: daily online adaptive radiotherapy