1. Validation and Modification of a Prediction Model for Acute Cardiac Events in Patients With Breast Cancer Treated With Radiotherapy Based on Three-Dimensional Dose Distributions to Cardiac Substructures.
- Author
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van den Bogaard VA, Ta BD, van der Schaaf A, Bouma AB, Middag AM, Bantema-Joppe EJ, van Dijk LV, van Dijk-Peters FB, Marteijn LA, de Bock GH, Burgerhof JG, Gietema JA, Langendijk JA, Maduro JH, and Crijns AP
- Subjects
- Adolescent, Adult, Age Factors, Aged, Breast Neoplasms surgery, Dose-Response Relationship, Radiation, Female, Follow-Up Studies, Heart Ventricles radiation effects, Humans, Imaging, Three-Dimensional, Incidence, Mastectomy, Segmental, Middle Aged, Myocardial Ischemia mortality, Percutaneous Coronary Intervention statistics & numerical data, Probability, Proportional Hazards Models, Radiotherapy Planning, Computer-Assisted, Risk Assessment methods, Risk Factors, Tomography, X-Ray Computed, Young Adult, Breast Neoplasms radiotherapy, Heart radiation effects, Myocardial Infarction epidemiology, Radiation Dosage
- Abstract
Purpose A relationship between mean heart dose (MHD) and acute coronary event (ACE) rate was reported in a study of patients with breast cancer (BC). The main objective of our cohort study was to validate this relationship and investigate if other dose-distribution parameters are better predictors for ACEs than MHD. Patients and Methods The cohort consisted of 910 consecutive female patients with BC treated with radiotherapy (RT) after breast-conserving surgery. The primary end point was cumulative incidence of ACEs within 9 years of follow-up. Both MHD and various dose-distribution parameters of the cardiac substructures were collected from three-dimensional computed tomography planning data. Results The median MHD was 2.37 Gy (range, 0.51 to 15.25 Gy). The median follow-up time was 7.6 years (range, 0.1 to 10.1 years), during which 30 patients experienced an ACE. The cumulative incidence of ACE increased by 16.5% per Gy (95% CI, 0.6 to 35.0; P = .042). Analysis showed that the volume of the left ventricle receiving 5 Gy (LV-V5) was the most important prognostic dose-volume parameter. The most optimal multivariable normal tissue complication probability model for ACEs consisted of LV-V5, age, and weighted ACE risk score per patient (c-statistic, 0.83; 95% CI, 0.75 to 0.91). Conclusion A significant dose-effect relationship was found for ACEs within 9 years after RT. Using MHD, the relative increase per Gy was similar to that reported in the previous study. In addition, LV-V5 seemed to be a better predictor for ACEs than MHD. This study confirms the importance of reducing exposure of the heart to radiation to avoid excess risk of ACEs after radiotherapy for BC.
- Published
- 2017
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