Factors affecting cardiac dose in left-sided whole breast radiotherapy in a single institution
PO-1216
Abstract
Factors affecting cardiac dose in left-sided whole breast radiotherapy in a single institution
Authors: Arpad Tot1,2, Borislava Petrović1,3, Milana Marjanović4,3, Ivan Gencel1, Nemanja Golubovac1, Olivera Ivanov5,6, Jelena Ličina5,6, Milana Mitrić-Ašković5
1Oncology Institute of Vojvodina, Medical Physics, Sremska Kamenica, Serbia; 2Institute od Nucelar Sciences Vinca, Physics, Vinca, Serbia; 3University of Novi Sad, Faculty of Sciences, Physics, Novi Sad, Serbia; 4Oncology Institute of Vojvodina , Medical Phyiscs, Sremska Kamenica, Serbia; 5Oncology Institute of Vojvodina, Radiotherapy, Sremska Kamenica, Serbia; 6University of Novi Sad, Faculty of Medicine, Novi Sad, Serbia
Show Affiliations
Hide Affiliations
Purpose or Objective
Left-sided
whole breast radiotherapy (RT) can increase the risk of cardiac disease with
increasing dose. Therefore, one of the main concerns is to reduce excessive
dose to heart, LAD and lungs. The purpose of this study was to assess the
correlations of left lung volume, mean heart distance, chest wall separation
with heart and lung dose in women with left-sided breast cancer receiving whole
breast radiotherapy. The correlations are used during the CT scanning for immediate
decision on the use of most appropriate technique for particular patient (breath
hold techniques vs. free breathing).
Material and Methods
133 female patients treated with left-sided breast RT at
Oncology Institute of Vojvodina (Sremska Kamenica, Serbia) between 2017 and
2020 were analyzed. Left lung volume (LLV), left lung mean dose (LLD), mean
heart dose (MHD), heart dose V25 Gy, V20 Gy, V16 Gy, V8 Gy, left anterior
descending artery (LAD) mean dose (LADm), LAD max dose (LADM), chest wall
separation (CWS), central lung distance (CLD), max heart distance (mHD) were
collected from treatment planning system Monaco (Elekta, UK). A two-tailed
Student's t-test and Pearson's correlation test were performed for statistical
analysis.
Results
Median
values were: left lung volume (LLV) was 1429.82 (462.80) cm3, chest
wall separation (CWS) 22.77 (3.50) cm, max heart distance (mHD) 1.97 (0.60) cm,
central lung distance (CLD) 0.96 (0.86) cm, mean heart dose (MHD) 2.28 (1.28)
Gy, LAD mean dose (LADm) 30.27 (11.61) Gy, LAD max dose (LADM) 11.64 (6.99) Gy,
mean left lung dose (LLD) 4.45 (1.45) Gy. Statistically significant (p<
0.05) negative correlations was found between LLV and MHD (r=-0.546), HD V25
(r=0.-500), HD V20 (r=-0.536), HD V16 (r=-0.563), HD V8 (r=-0.618), LAD mean
(r=-0.588), LAD max (r=-0.556). Positive correlation was wound between CWS and
HDmean (r=0.342) and LLV and mean LLD (r=0.182). There was no statistically
significant correlation between CWS and mean LLD, and CLD and MHD. For patients
(N= 111) whose MHD < 3.2 Gy (clinically acceptable) mean CSW was 22.31
(3.49) cm and for patients (N=22) with MHD> 3.2 Gy mean CWS was 25.05 (2.61)
cm.
Conclusion
RT
improves survival rate, but also increases risk of heart diseases. A linear
relationship between LLV and heart dose was observed. According to our results
it is possible using (CWS vs. MHD) values to determine if there is a need for
breath hold technique already on CT without making RT plan. In our Institute
acceptable MHD is 3.2 Gy, which is in most cases accomplished when CWS is
bellow 25 cm. Beside the observed (CWS) criteria, MHD should be considered
during planning when determining the most appropriate RT technique. This reduces
the time between CT simulation and beginning of the RT treatment and travel
costs for patients. CWS correlation could be promising clinical parameter since
it could offer an estimation of mean heart dose and necessity of deep
inspiration technique.