Breathing room.

Pneumonitis is uncommon after lung SBRT, but what are good risk factors and dosimetric thresholds to guide treatment planning? In this retrospective analysis of a large UK database (n=1266) of lung SBRT, 6.7% of patients developed symptomatic radiation pneumonitis (RP) with <1% developing grade 3+ RP. Mean lung dose was the only factor in multivariable analysis associated with RP risk. Using ROC curve analysis, the authors found that PTV volume > 27cc, mean lung dose > 3.7 Gy, V20 > 4.6%, and V12.5 > 9.5% were key thresholds for predicting an increased risk of symptomatic RP. Obviously, these factors are closely linked and may not be independently modifiable. But, TBL is that these dosimetric thresholds may help identify patients at increased risk of RP after lung SBRT. | Saha, Radiother Oncol 2020