Limiting the risk of cardiac toxicity with esophageal-sparing intensity modulated radiotherapy for locally advanced lung cancers

Abstract

Background: Intensity modulated radiotherapy (IMRT) is routinely utilized in the treatment of locally advanced non-small cell lung cancer (NSCLC). RTOG 0617 found that overall survival was impacted by increased low (5 Gy) and intermediate (30 Gy) cardiac doses. We evaluated the impact of esophageal-sparing IMRT on cardiac doses with and without the heart considered in the planning process and predicted toxicity compared to 3D-conventional radiotherapy (3DCRT). Methods: Ten consecutive patients with N2 Stage III NSCLC treated to 60 Gy in 30 fractions, betweenFebruary 2012 and September 2014, were evaluated. For each patient, 3DCRT and esophageal-sparing IMRT plans were generated. IMRT plans were then created with and without the heart considered in the optimization process. To compare plans, the dose delivered to 95% and 99% of the target (D 95% and D 99% ), and doses to the esophagus, lung and heart were compared by determining the volume receiving X dose (V XGy ) and the normal tissue complication probability (NTCP) calculated. Results: IMRT reduced maximum esophagus dose to below 60 Gy in all patients and produced significant reductions to V 50Gy , V 40Gy and esophageal NTCP. The cost of this reduction was a non-statistically, nonclinically significant increase in low dose (5 Gy) lung exposure that did not worsen lung NTCP. IMRT plans produced significant cardiac sparing, with the amount of improvement correlating to the amount of heart overlapping with the target. When included in plan optimization, for selected patients further sparing of the heart and improvement in heart NTCP was possible. Conclusions: Esophageal-sparing IMRT can significantly spare the heart even if it is not considered in the optimization process. Further sparing can be achieved if plan optimization constrains low and intermediate heart doses, without compromising lung doses.

Advanced radiation techniques for locally advanced non-small cell lung cancer: intensity-modulated radiation therapy and proton therapy

“…The secondary analyses of RTOG 0617 suggest that lower heart doses correlate with improved OS and QoL, and that IMRT can better spare the heart than 3DCRT, consistent with the majority of planning studies (21)(22)(23)(24)26,29,63). In a pooled analysis of dose escalation trials using 3DCRT to treat stage III NSCLC in the setting of induction/concurrent chemotherapy, Wang et al found that 23% of patients experienced a symptomatic cardiac event at a median of 26 months to first event posttreatment, and that higher heart doses and baseline cardiac morbidity predicted for these events (67).…”

“…Planning studies comparing IMRT to 3DCRT for NSCLC have consistently demonstrated that IMRT allows for superior coverage of the PTV and greater avoidance of healthy lung parenchyma, heart, esophagus and spinal cord (21)(22)(23)(24)(25)(26)(27)(28)(29). When designing IMRT plans, beam angle optimization determines which OARs will be preferentially spared.…”

Dosimetric advantages of intensity modulated radiation therapy in locally advanced lung cancer

“…A recent analysis by Woodford et al compared normal tissue doses among 3 plans for 10 patients with N2 NSCLC: (1) 3D-CRT, (2) IMRT, and (3) IMRT with cardiac constraints 20 . With a prescription dose of 60 Gy and normalization for target coverage, IMRT significantly reduced the dose to the esophagus and heart compared with 3D-CRT.…”

“…Although comparisons of 3D-CRT and IMRT for lung cancer have been reported in the literature, few have directly quantified the dosimetric benefit of IMRT. 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 The limitations and shortcomings of these studies likely influence current reimbursement policies and practice patterns in which 3D-CRT is the default approach; thus, quantifying the potential advantage with this technology is important. Using a unique, prospectively obtained dataset, we sought to assess this question.…”

The margin of internal risk volume on atrial septal and ventricular septal based on electrocardiograph gating 4DCT

“…Radiation-induced heart disease (RIHD) often results from radiotherapy for thoracic malignant tumors such as breast, esophageal, and central lung cancer (1)(2)(3)(4). RIHD may include acute pericarditis, coronary atherosclerosis, myocardial injury, cardiac conduction system abnormality, and heart valve disease (5) and the few studies investigating the pathogenesis of RIHD show cardiac conduction abnormality, arrhythmia, and intracardiac conduction block as its main manifestations (6).…”