A cardiac sparing technique for breast cancer radiation treatment

Abstract

s / The Breast 23 (2014) S1eS6 S2 A CARDIAC SPARING TECHNIQUE FOR BREAST CANCER RADIATION TREATMENT Christopher Kelly, Kirsten Stuart, Tim Wang, Drew Latty, Verity Ahern. Crown Princess Mary Cancer Centre (CPMCC), and Breast Cancer Institute NSW, Westmead Hospital, Australia Background: Historically left-sided breast cancer radiation treatment has been associatedwith an excess risk of cardiac deaths1, and every additional 1Gy mean cardiac dose results in a relative increase in cardiac events of 7.4%2. Methods: A deep inspiratory breath hold (DIBH) techniquewas introduced as a method of reducing the volume of heart in breast / chest wall tangential radiation treatment at CPMCC in 2010, one of the few centres using this technique in Australia. This study evaluates the impact of DIBH on cardiac radiation dose. Results: A total of 51 patients underwent an attempt at radiation treatment simulation by DIBH as well as the conventional ‘free breathing’ (FB) approach between December 2010 and April 2013. Thirty eight patients proceeded to treatment delivery by DIBH. Thirteen patients did not undergo treatment by DIBH, either because DIBH did not reduce the cardiac dose (6 patients) or because they were not able to follow instructions for DIBH (7 patients). For the 38 patients who underwent DIBH, the simulated size of the heart measured as a volume varied between FB and DIBH by 72% 115%. The mean irradiated heart dose calculated by simulation was 6.2Gy by the DIBH technique and higher by the FB technique for all 38 patients .It was a mean of 7.0Gy for the 13 patients treated by FB .Six of 38 patients underwent fluoroscopic imaging of one radiation field during treatment on at least two occasions. For the six patients as a group, the heart moved between 1 and 6mm during the fluoroscopic imaging. Conclusions: DIBH is a suitable technique to reduce the cardiac volume irradiated for some patients with left sided breast cancer. We are now exploring the best method of measuring cardiac position during treatment, and how we can help more women cope with this procedure.