Author: Ibrahim Aref, David Bergman, Justine M. Cunningham, Payton Dolan, Aharon Feldman, Yimei Huang, Joshua P. Kim, Brett M. Miller, Emily Moats, Benjamin Movsas, Kundan S Thind 👨🔬
Affiliation: Henry Ford Health 🌍
Purpose: Cardiac radiation dose is directly associated with adverse cardiac events which are predictive of mortality in lung cancer patients. In fractionated lung radiotherapy, studies have shown a high variance of accumulated heart dose due to setup uncertainties. Resulting increases in cardiac dose exposure may be mitigated through online adaptive radiotherapy.
Methods: An internal IRB approved whole heart sparing ethos adaptive radiotherapy for lung cancer (HEART-LC) trial, aimed to decrease heart exposure using adaptive radiotherapy was developed. Eligibility criteria includes lung cancer patients with targets near (5cm) or overlapping with cardiac structures. Enrolled patients are planned with conventional or stereotactic body radiotherapy and treated utilizing an adaptive workflow. Adaptation criteria includes a reduction in organ at risk (OAR) dose, focusing on preserving or decreasing cardiac doses below the defined constraints, without sacrificing dose coverage or surrounding OARs.
Results: Five patients have been enrolled on HEART-LC, four have completed treatment. One patient with a left lower lobe lesion overlapping with the heart, treated to 66Gy in 33 fractions, required adaptation during two fractions to reduce the maximum heart dose to within allowable limits (D0.03cc<68Gy). Another patient with a right lower lobe lesion overlapping with the heart, treated to 50Gy in 5 fractions, required adaptation for all fractions to maintain the heart maximum dose within allowable limits (D0.03cc<38Gy). If the scheduled plan was delivered for all five fractions, the accumulated maximum heart dose would have exceeded 50Gy. The remaining three patients have not required adaptation.
Conclusion: Further enrollment of patients is necessary to continue investigating the impact of HEART-LC in reducing cardiac dose. Future work includes evaluating HEART-LC’s impact on quality-of-life metrics using Patient Reported Outcomes, the capability of delineating cardiac substructures on online cone beam CT images and investigating the role of online adaptive radiotherapy in reducing cardiac substructure doses.