Reduction of cardiac and pulmonary complication probabilities after breathing adapted radiotherapy for breast cancer.
OBJECTIVE
Substantial reductions of cardio-pulmonary radiation doses can be achieved using voluntary deep inspiration breath-hold (DIBH) or free breathing inspiration gating (IG) in radiotherapy after conserving surgery for breast cancer. The purpose of this study is to evaluate the radiobiological implications of such dosimetric benefits.


METHODS
Patients from previously reported studies were pooled for a total of 33 patients. All patients underwent DIBH and free breathing (FB) scans, and 17 patients underwent an additional IG scan. Tangential conformal treatment plans covering the remaining breast, internal mammary, and periclavicular nodes were optimized for each scan, prescription dose 48 Gy. Normal tissue complication probabilities were calculated using the relative seriality model for the heart, and the model proposed by Burman et al. for the lung.


RESULTS
Previous computed tomography studies showed that both voluntary DIBH and IG provided reduction of the lung V50 (relative volume receiving more than 50% of prescription dose) on the order of 30-40%, and a 80-90% reduction of the heart V50 for left-sided cancers. Corresponding pneumonitis probability of 28.1% (range, 0.7-95.6%) for FB could be reduced to 2.6% (range, 0.1-40.1%) for IG, and 4.3% (range, 0.1-59%) for DIBH. The cardiac mortality probability could be reduced from 4.8% (range, 0.1-23.4%) in FB to 0.5% (range, 0.1-2.6%) for IG and 0.1% (range, 0-3.0%) for DIBH.


CONCLUSIONS
Remarkable potential is shown for simple voluntary DIBH and free breathing IG to reduce the risk of both cardiac mortality and pneumonitis for the common technique of adjuvant tangential breast irradiation.
Korreman
Stine S
SS
Department of Radiation Oncology, The Finsen Centre, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark. stine.k@rh.dk
Pedersen
Anders N
AN
Aarup
Lasse Rye
LR
Nøttrup
Trine J
TJ
Specht
Lena
L
Nyström
Håkan
H
D000368:Aged; D000465:Algorithms; D001943:Breast Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006321:Heart / Q000528:radiation effects*; D006801:Humans; D001239:Inhalation; D008168:Lung / Q000528:radiation effects*; D008875:Middle Aged; D011336:Probability; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000401:mortality*; D017564:Radiation Pneumonitis / Q000401:mortality; D011853:Radiobiology; D018714:Radiotherapy, Adjuvant; D020266:Radiotherapy, Conformal / Q000379:methods*; D012119:Respiration