Prediction of radiation-related cardiotoxicity using F-18 FDG PET in non-small-cell lung cancer

Abstract Background Radiation-related cardiotoxicity has been refocused nowadays as the follow-up was increased amomg the patients with advanced lung cancer. The early recognition of the occult cardiotoxicity enables the early intervention preventing clinically significant cardiac events or worsening of severity. Purpose We aim to search whether the F-18 fluorodeoxyglucose positron emission tomography (FDG PET) performed immediately after radiotherapy could predict the late cardiac events. Methods We retrospectively enrolled 133 patients with locally advanced, unresectable stage III NSCLC who underwent F-18 fluorodeoxyglucose positron emission tomography (FDG PET) immediately after CCRT for the response evaluation and survived at least for 6 months. Heart was recontoured according to the RTOG 0617 secondary analysis atlas for the dose volume analysis. Standardized uptake values (SUV) of the left ventricular myocardium were measured on FDG PET images. The patients were regularly followed up for the disease progression and complications. The primary end-point was the cardiac events grade ≥2 based on the Common Terminology Criteria for Adverse Events (version 5.0). Results FDG PET was performed at median interval of 11 days after CCRT. Fourty-two patients experienced cardiotoxicity during a median follow-up of 47 months (range, 12 – 123 months). In univariable analysis, mean heart dose, maximum SUV of the left ventricle (LV SUVmax), white blood cell count, and diabetes were associated with the risk of cardiotoxicity. In multivariable analysis, only higher mean heart dose (>11.1 Gy, hazard ratio 3.930 [95% confidence interval 1.933–7.988]; p=0.0002) and higher LV SUVmax (>12.84, 2.189 [1.162–4.124]; p=0.0152) were independently associated with increased risk of cardiotoxicity. In subgroup analyses, LV SUVmax remained predictive of cardiotoxicity among those with higher mean heart dose, but not among those with lower mean heart dose. Conclusion Early FDG PET after CCRT for NSCLC could predict the late cardiac events, especially in patients with high dose cardiac irradiation. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): This work was supported by a grant of the Basic Science Research Program through the National Research Foundation funded by the Ministry of Education, Republic of Korea (Principal Investigator: Sang-Geon Cho)