ESTRO 2024 - Abstract Book

S1875

Clinical - Mixed sites, palliation

ESTRO 2024

Conclusion:

In our cohort 5#iSABR was non-inferior to 3#SABR despite a significantly lower dose (BED10). Five fraction isotoxic radiotherapy offers significant practical advantages as it is robust to OAR movement, allowing easier delivery with less need for online clinician review. In the group of patients who received 5#iSABR delivering 3#SABR would have resulted in areas of the PTV receiving significantly less than the prescription dose. It is not known if this has a clinical impact, but our data supports the safe and effective use of isotoxic planning to provide more homogenous target coverage. We must acknowledge numerous limitations of our data, including retrospective design, inherently bias stratification, small sample size and median follow up of only 18 months. We feel striving for highest possible BED remains important, for the small proportion of patients who may achieve long-term disease control. Five fraction isotoxic radiotherapy may be of particular interest for treating oligoprogresive disease, allowing resources to be focused on dose escalation for the oligometastatic population.