Pre-treatment non-target lung FDG-PET uptake predicts symptomatic radiation pneumonitis following Stereotactic Ablative Radiotherapy (SABR).
To determine if pre-treatment non-target lung FDG-PET uptake predicts for symptomatic radiation pneumonitis (RP) following lung stereotactic ablative radiotherapy (SABR).



We reviewed a 258 patient database from our institution to identify 28 patients who experienced symptomatic (grade ⩾ 2) RP after SABR, and compared them to 57 controls who did not develop symptomatic RP. We compared clinical, dosimetric and functional imaging characteristics between the 2 cohorts including pre-treatment non-target lung FDG-PET uptake.



Median follow-up time was 26.9 months. Patients who experienced symptomatic RP had significantly higher non-target lung FDG-PET uptake as measured by mean SUV (p < 0.0001) than controls. ROC analysis for symptomatic RP revealed area under the curve (AUC) of 0.74, with sensitivity 82.1% and specificity 57.9% with cutoff mean non-target lung SUV > 0.56. Predictive value increased (AUC of 0.82) when mean non-target lung SUV was combined with mean lung dose (MLD). We developed a 0-2 point model using these 2 variables, 1 point each for SUV > 0.56 or MLD > 5.88 Gy equivalent dose in 2 Gy per fraction (EQD2), predictive for symptomatic RP in our cohort with hazard ratio 10.01 for score 2 versus 0 (p < 0.001).



Patients with elevated pre-SABR non-target lung FDG-PET uptake are at increased risk of symptomatic RP after lung SABR. Our predictive model suggests patients with mean non-target lung SUV > 0.56 and MLD > 5.88 Gy EQD2 are at highest risk. Our predictive model should be validated in an external cohort before clinical implementation.
Department of Radiation Oncology, Stanford University School of Medicine, United States.
Aadel A
AA
Chaudhuri
Department of Radiation Oncology, Stanford University School of Medicine, United States.
Michael S
MS
Binkley
Quantitative Sciences Unit, Stanford University School of Medicine, United States.
Joseph
J
Rigdon
Department of Radiation Oncology, Stanford University School of Medicine, United States.
Justin N
JN
Carter
Department of Radiation Oncology, Stanford University School of Medicine, United States.
Sonya
S
Aggarwal
Department of Radiation Oncology, Stanford University School of Medicine, United States.
Sara A
SA
Dudley
Department of Radiation Oncology, Stanford University School of Medicine, United States.
Yushen
Y
Qian
Department of Radiation Oncology, Stanford University School of Medicine, United States.
Kiran A
KA
Kumar
Department of Radiation Oncology, Stanford University School of Medicine, United States; Stanford Cancer Institute, Stanford University School of Medicine, United States.
Wendy Y
WY
Hara
Department of Radiation Oncology, Stanford University School of Medicine, United States.
Michael
M
Gensheimer
Department of Medicine, Division of Pulmonary and Critical Care Medicine, Stanford University School of Medicine, United States.
Viswam S
VS
Nair
Department of Radiation Oncology, Stanford University School of Medicine, United States; Stanford Cancer Institute, Stanford University School of Medicine, United States.
Peter G
PG
Maxim
Department of Radiation Oncology, University of Toronto, Princess Margaret Cancer Centre, Canada.
David B
DB
Shultz
Department of Radiation Oncology, Stanford University School of Medicine, United States.
Karl
K
Bush
Department of Radiation Oncology, University of Southern California School of Medicine, United States.
Nicholas
N
Trakul
Department of Radiation Oncology, Stanford University School of Medicine, United States; Stanford Cancer Institute, Stanford University School of Medicine, United States.
Quynh-Thu
QT
Le
Department of Radiation Oncology, Stanford University School of Medicine, United States; Stanford Cancer Institute, Stanford University School of Medicine, United States; Institute for Stem Cell Biology & Regenerative Medicine, Stanford University School of Medicine, United States. Electronic address: diehn@stanford.edu.
Maximilian
M
Diehn
Department of Radiation Oncology, Stanford University School of Medicine, United States; Stanford Cancer Institute, Stanford University School of Medicine, United States. Electronic address: BWLoo@stanford.edu.
Billy W
BW
Loo
Department of Radiology and Nuclear Medicine, Stanford University School of Medicine, United States. Electronic address: henryguo@stanford.edu.
Haiwei Henry
HH
Guo
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D017564:Radiation Pneumonitis / Q000209:etiology*; D016634:Radiosurgery / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies
D019788:Fluorodeoxyglucose F18
Fluorodeoxyglucose positron emission tomography (FDG-PET); Lung cancer; Mean lung dose; Mean non-target lung SUV; Radiation pneumonitis; Stereotactic ablative radiotherapy (SABR)