Heart irradiation as a risk factor for radiation pneumonitis.
OBJECTIVE
to investigate the potential role of incidental heart irradiation on the risk of radiation pneumonitis (RP) for patients receiving definitive radiation therapy for non-small-cell lung cancer (NSCLC).


METHODS
two hundred and nine patient datasets were available for this study. Heart and lung dose-volume parameters were extracted for modeling, based on Monte Carlo-based heterogeneity corrected dose distributions. Clinical variables tested included age, gender, chemotherapy, pre-treatment weight-loss, performance status, and smoking history. The risk of RP was modeled using logistic regression.


RESULTS
the most significant univariate variables were heart related, such as heart heart V65 (percent volume receiving at least 65 Gy) (Spearman Rs = 0.245, p < 0.001). The best-performing logistic regression model included heart D10 (minimum dose to the hottest 10% of the heart), lung D35, and maximum lung dose (Spearman Rs = 0.268, p < 0.0001). When classified by predicted risk, the RP incidence ratio between the most and least risky 1/3 of treatments was 4.8. The improvement in risk modeling using lung and heart variables was better than using lung variables alone.


CONCLUSIONS
these results suggest a previously unsuspected role of heart irradiation in many cases of RP.
Huang
Ellen X
EX
Department of Radiation Oncology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110-1093, USA.
Hope
Andrew J
AJ
Lindsay
Patricia E
PE
Trovo
Marco
M
El Naqa
Issam
I
Deasy
Joseph O
JO
Bradley
Jeffrey D
JD
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D002289:Carcinoma, Non-Small-Cell Lung / Q000532:radiotherapy*; D005260:Female; D006321:Heart / Q000528:radiation effects*; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008175:Lung Neoplasms / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009010:Monte Carlo Method; D011014:Pneumonia / Q000209:etiology*; D011832:Radiation Injuries / Q000150:complications* / Q000209:etiology; D011874:Radiometry; D012307:Risk Factors; D012720:Severity of Illness Index