RT in left-sided breast cancer can lead to an increased risk of coronary artery disease (CAD). The type of RT technique and volumes, use of systemic therapy and patient related factors determine the risk of CAD. However, these cardiac events do not manifest until 10 years after RT.
We contoured the coronary artery segments in women with left-sided breast cancer and analyzed the dose distribution parameters. The mean and maximum doses for the segments of coronary arteries were noted in 15 such patients who underwent adjuvant RT (42.5 Gy in 16 fractions). All the patients were treated by 3DCRT with standard two-field tangential RT technique, with or without a supraclavicular field.
Whole heart dose may not be the best predictor of all types of radiation induced heart disease. It was observed that the maximum and mean dose to the coronary arteries was 26.4 Gy and 8.8 Gy respectively. This predicts the average risk of coronary artery disease.
RT to the left chest wall can expose patients to an increased risk of CAD and there seems to be an association between the location of the RT beam and the location of the coronary events. Hence, radiation oncologists should utilize the tools and techniques available to reduce doses to cardiovascular structures.
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