Differential inflammatory response dynamics in normal lung following stereotactic body radiation therapy with protons versus photons.

ABSTRACT: BACKGROUND AND PURPOSE:To compare time-dependent changes in lung parenchyma of early-stage non-small cell lung carcinoma (NSCLC) patients after stereotactic body radiation therapy with protons (SBPT) or photons (SBRT). MATERIALS AND METHOD:We retrospectively identified NSCLC patients treated with SBPT and matched each one with a SBRT patient by patient, tumor, and treatment characteristics. Lung parenchyma on serial post-treatment chest computer tomography (CT) scans was deformably registered with the treatment plan to analyze lung density changes as function of dose, quantified by Houndsfield Unit (HU)/Gy. A thoracic radiologist also evaluated the CTs using an established grading system. RESULTS:We matched 23 SBPT/SBRT pairs, including 5 patients treated with both modalities (internally matched cohort). Normal lung response following SBPT significantly increased in the early time period (CTs acquired <6?months, median 3?months) post-treatment, and then did not change significantly in the later time period (CTs acquired 6-14?months, median 9?months). For SBRT, the normal lung response was similar to SBPT in the early time period, but then increased significantly from the early to the late time period (p?=?0.007). These differences were most pronounced in sensitive (response >6 HU/Gy) patients and in the internally matched cohort. However, there was no significant difference in the maximum observed response in the entire cohort over all time periods, median 3.4 [IQR, 1.0-5.4] HU/Gy (SBPT) versus 2.5 [1.6-5.2] HU/Gy (SBRT). Qualitative radiological evaluation was highly correlated with the quantitative analysis (p?

SUBMITTER: Li Y 

PROVIDER: S-EPMC6592748 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature