Международный журнал воспаления, рака и интегративной терапии

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Relationship between Cardiac Toxicities and Radiation Dose in Early-Stage Non-Small Cell Lung Cancer Patients Treated with Stereotactic Body Radiotherapy for Tumors Adjacent to the Heart

Nhu Ngoc Nguyen, Hong Nam Vu, Thanh Toan Nguyen, Quoc Viet Tran, Viet Cuong Nguyen, Duc Tien Dao, Son Giang Vu, Hiroshi Onishi

Background and purposes: Stereotactic Body Radiotherapy (SBRT) is the main treatment modality for earlystage NSCLC patients who cannot undergo the operation because of its excellent local control as well as Overall Survival (OS) rates. However, in patients with centrally located tumors, the radiation induced side effects to surrounding normal tissues can limit the treatment outcomes. This study’s goal is to examine the correlations of SBRT with cardiac toxicities and the OS rate in early-stage non-small cell lung cancer patients whose tumors are close to the heart following irradiation.

Methods: Forty-five patients who underwent SBRT with tumors close to the heart (<2 cm) were included. We reviewed dose-volume histograms and selected heart dosimetric parameters, such as maximum and mean dose, percentages of tumor volume receiving >5 Gy, >10 Gy and >20 Gy. The correlation between cardiac toxicities following SBRT, the OS rate, and cardiac dose metrics, clinical factors were assessed by multiple variate analyses using the Cox’s regression model.

Results: The 3-year overall survival rate was 45% with a median follow-up time was 22 months. The following heart dose volume histogram metrics were recorded (median, range): maximum dose (14.2 Gy, 0-79.4 Gy), mean dose (2 Gy, 0-24.7 Gy) and percentage volumes receiving >5 Gy (9.5%, 0%-100%), >10 Gy (0.3%, 0%-95.5%), and >20 Gy (0%, 0%-51.7%). Sixteen (35.5%) patients had a preexisting cardiovascular history, most commonly ischemia or hypertension. Two patients (4.5%) developed grade ≥ 3 cardiac toxicities, one of whom with a history of cardiomegaly died because of heart failure. There was a statistically significant increase in cardiac abnormalities after stereotactic body radiotherapy. We identified no direct relationship between overall survival or cardiac toxicities and any cardiac dose-volume histogram parameters. However, preexisting heart disease was found as a predictor for overall survival (p-value=0.04)

Conclusion: SBRT is safe for treating early-stage NSCLC patients with tumors close to the heart. However, it might increase the risk of cardiac abnormalities among patients with preexisting heart conditions, and this should be carefully considered when implementing stereotactic body radiotherapy.