2323 - Risk of Cardiac Toxicity Influences Treatment Decisions in Lung Cancer: A National Survey

Purpose/Objective(s): Although lung cancer remains the leading cause of cancer-related death, treatment paradigms have advanced such that the number of long-term survivors has increased. Consequently, survivorship issues, such as the long-term toxicity of treatment, are moving to the forefront of oncologic research. To that end, radiation-induced heart disease (RIHD) remains a significant complication among patients treated with thoracic radiation for lung cancer. As predictive markers of cardiotoxicity are defined, oncologists will face treatment decisions regarding the therapeutic ratio of oncologic outcomes and cardiac toxicity. The objective of the present study was to survey practicing experts in lung cancer radiation oncology as to their preferred treatment strategy in theoretical scenarios where the risk of cardiac toxicity was known de novo to quantify the clinical utility of interventions that inform cardiac risk from treatment.

Materials/Methods: We distributed a survey to national and international experts in thoracic radiation oncology. The survey described 3 scenarios for a patient with locally-advanced non-small cell lung cancer to be treated with radiotherapy: 1) no cardiotoxicity information available, 2) <10% risk of cardiotoxicity, and 3) >25% risk of cardiotoxicity. Radiation oncologists were asked to assess decision-making for the 3 cardiotoxicity risk scenarios regarding referring patients to a cardiologist, changing the radiation prescription, changing the target margins, changing the doses allowed to the heart, changing dosimetric plan objectives, and changing follow up intervals. Kappa statistics, one sample t and Wilcoxon test, and McNamara test were used to analyze changes in physician preferences, depending on the type of question.

Results: The survey’s overall response rate was 75% (42 respondents out of 56 surveyed). We observed changes in clinical decision-making in response to the high risk of cardiac toxicity. Our respondents reported increased referrals to cardiology, changes in radiation dose towards a more conservative approach (60 Gy in 30 fractions), increased willingness to crop treatment volumes to meet heart constraints, and more emphasis on conservative heart constraints (mean heart dose < 10 Gy). For example, 88% of radiation oncologists would refer the patient to a cardiologist in scenario 3 (cardiotoxicity risk high) versus only 12% in scenario 1 (cardiotoxicity risk unknown). Increasing degrees of cardiac risk did not appear to affect clinical judgment towards follow-up intervals or the relative priority of cardiac dose compared to other objectives.

Conclusion: Our study represents the largest survey of theoretical practice patterns in response to cardiac biomarkers for thoracic radiotherapy and suggests that predictive cardiac biomarkers would influence treatment decisions with the potential to improve the lives of patients with lung cancer.