[Left-sided breast cancer locoregional radiation therapy with rotational intensity-modulated irradiation and deep inspiration breath hold: Dosimetric comparison]

Abstract

Purpose: Adjuvant left-sided breast cancer locoregional radiotherapy can be accounted for long-term cardiac toxicity. The deep inspiration breath hold techniques can reduce cardiac doses. Only a few studies have investigated rotational intensity-modulated radiotherapy with deep inspiration breath hold.

Material and methods: We conducted a dosimetric study comparing rotational intensity-modulated radiotherapy in free breathing with deep inspiration breath hold for irradiation of left breast cancer and locoregional lymph nodes. Doses to organs at risk were compared, as well as doses to coronary arteries, left anterior descending coronary artery region, and aortic valve.

Results: The data from nine patients were included in the study. Treatment plans were comparable for target volumes. The deep inspiration breath hold delivery technique, compared with free breathing, reduced radiation dose to the heart (mean dose 4.8Gy vs. 6.6Gy, p=0.008; dose in 2% of the volume 16.8Gy vs. 23.3Gy, p=0.008; volume receiving 25Gy 0.8% vs. 2,2%, p=0.008; volume receiving 30Gy 0.4% vs. 1.2%, p=0.009), as well as to the right coronary artery (mean dose 6Gy vs. 8.9Gy, p=0.028), to the left anterior descending artery (mean dose 9.6Gy vs. 14.6Gy, p=0.021), to the left anterior descending coronary artery region (dose in 2% of the volume 17.4Gy vs. 24.6Gy, p=0.021), and to the aortic valve (mean dose 4.8Gy vs. 7Gy, p=0.028). Other doses to organs at risk were similar.

Conclusion: Rotational intensity-modulated radiotherapy with deep inspiration breath hold is associated with better sparing of the heart, on the right and left anterior descending coronary arteries, and on the aortic valve, compared with free breathing techniques, for adjuvant left breast cancer locoregional irradiation.

Keywords: Breast cancer; Cancer du sein; Deep inspiration breath hold; Inspiration profonde; Intensity-modulated radiotherapy; Radiothérapie avec modulation.