Hamid Ghaznavi - Department of Radiology, Faculty of Paramedical school, Kurdistan university of medical sciences
Amir Jafari - Radiation therapy division, Ayatollah Khansari Hospital, Arak University of Medical Sciences, Arak, Iran

Introduction: After lumpectomy, radiation therapy is used to control the tumor and increase patient survival. Following radiation therapy, the organs at risk are vulnerable to toxicity and secondary cancer. Material and Methods: Thirty-two patients with early-stage of left breast cancer were selected for this study. Intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (۳DCRT) were planned to deliver the prescribed dose to the target volume. Considering baseline risk of heart disease, the excess absolute risk (EAR) of heart disease was calculated using the Reynolds risk score for ages ۵۰-۷۰. Results: There was a significant difference in ۱۰-year EAR of heart disease when comparing ۳DCRT plans to IMRT (p <۰.۰۵). The ۱۰-year EAR for IMRT in the low, median, and high-risk groups was superior to ۳DCRT.  Among factors involved in baseline risk, by increasing the age, the impact of smoking on increasing EAR was clearer compared to a family history of heart disease.  Conclusion: IMRT had a more uniform dose distribution and a better conformity-homogeneity index than ۳DCRT. However, the mean heart dose and subsequently the risk of heart disease significantly were lower in ۳DCRT. Considering baseline risk leads to accurate estimates of the heart disease risk after breast cancer radiotherapy.

Breast radiation therapy, Heart Diseases, Reynold score risk, Baseline risk