A Novel Method for Evaluating Early Tumor Response Based on Daily CBCT Images for Lung SBRT
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Department of Radiation Medicine, University of Kentucky, 800 Rose Street, Lexington, KY 40536, USA
2
Department of Radiology, University of Kentucky, 800 Rose Street, Lexington, KY 40536, USA
3
AdventHealth, 2501 N Orange Ave, Orlando, FL 32804, USA
*
Author to whom correspondence should be addressed.
Cancers 2024, 16(1), 20; https://doi.org/10.3390/cancers16010020
Submission received: 3 November 2023
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Revised: 7 December 2023
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Accepted: 11 December 2023
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Published: 19 December 2023
(This article belongs to the Special Issue 2nd Edition: Imaging and Therapy in Lung Cancer and Mesothelioma)
Simple Summary
The assessment of tumor response is important in evaluating cancer treatment and predicting clinical outcomes. The currently used response evaluation criteria in solid tumors (RECIST) are based on tumor size and have limitations in tumor response assessment. We proposed a novel radiologic parameter (R) that combines radiologic tumor changes in size, contrast, and density and utilized patients’ daily cone-beam computerized tomography (CBCT) to evaluate early tumor response to stereotactic radiation therapy (SBRT) for lung cancer. In total, 132 lung cancer patients with 134 tumors were selected for this study. The results of R agreed well with the radiologic assessment performed by an experienced radiologist. Therefore, R can be used for quick, inexpensive, and accurate tumor evaluation for lung SBRT treatment.
Abstract
Background: We aimed to develop a new tumor response assessment method for lung SBRT. Methods: In total, 132 lung cancer patients with 134 tumors who received SBRT treatment with daily CBCT were included in this study. The information about tumor size (area), contrast (contrast-to-noise ratio (CNR)), and density/attenuation (μ) was derived from the CBCT images for the first and the last fractions. The ratios of tumor area, CNR, and μ (RA, RCNR, Rμ) between the last and first fractions were calculated for comparison. The product of the three rations was defined as a new parameter (R) for assessment. Tumor response was independently assessed by a radiologist based on a comprehensive analysis of the CBCT images. Results: R ranged from 0.27 to 1.67 with a mean value of 0.95. Based on the radiologic assessment results, a receiver operation characteristic (ROC) curve with the area under the curve (AUC) of 95% was obtained and the optimal cutoff value (RC) was determined as 1.1. The results based on RC achieved a 94% accuracy, 94% specificity, and 90% sensitivity. Conclusion: The results show that R was correlated with early tumor response to lung SBRT and that using R for evaluating tumor response to SBRT would be viable and efficient.
