Cardiac substructures in hypofractionated treatment schedules in left sided breast cancer
PO-1225
Abstract
Cardiac substructures in hypofractionated treatment schedules in left sided breast cancer
Authors: Aswin Ravi1, VIBHAY PAREEK2, MANSI BARTHWAL2, GOPIKRISHNA SHYAM1, ADILA A1, DEVANGANA BORA1, VIVEK GHOSH1, SOHAM SANYAL1, SAI KUMAR SAMALA1, MANAVENDRA SINGH TANWAR1, SUDATTA MANDAL1, SUYASH PANDEY1, DANDA VANSI SAI PRAVEEN1, JHANSI PATTANAIK1, SUSHANT NIRALA1, AJIT PRIY SOLANKI1, RAHUL SISODIYA1, SEEMA SHARMA1, DAYA NAND SHARMA1, HARESH KP1, SUBHASH GUPTA1
1IRCH, AIIMS, RADIATION ONCOLOGY, NEW DELHI, India; 2NCI, AIIMS, RADIATION ONCOLOGY, NEW DELHI, India
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Purpose or Objective
Hypofractionation radiation
therapy in breast cancer are well- established treatment schedules. However, in
left-sided breast cancer, the doses to heart and cardiac substructures are not
well defined. In this study, we compare the radiation dose received by cardiac
and the substructures in left-sided breast cancer.
Material and Methods
Total 30 patients
with histopathologically proven ductal carcinoma in left sided breast cancer,
15 each treated with 26Gy in 5 fractions (Group A) and 40Gy in 15 fractions
(Group B) respectively. Planning Computerised Tomography (CT) was undertaken
for each patient and organs at risk including the cardiac substructures, whole
breast, heart, lungs, and contra lateral breast was contoured for each patient.
Radiotherapy plans were made by standard tangent field. Mean and maximum heart
dose, LAD, RCA, LCA and Left circumflex artery mean and V5 of right lung, and
mean, V5, V10 and V20 of left lung, mean dose and V2 of contra lateral breast
were calculated for each patient and compared using student’s T test.
Results
Mean doses to the
heart were 16.4Gy and 8.45Gy respectively and left lung mean dose, V5, V10 and
V20 were 5.91Gy, 14%, 12.8%, 11.7%; and 7.83Gy, 20.4%, 18.6% and 14.7% in group
A and B, respectively. The dose to the distal LAD was significantly higher than
proximal LAD both in both plans (p<0.001) signifying the need for contouring
the distal LAD. Similarly, the doses were reduced in left circumflex artery
with group with trending towards significance. There was no statistically significant
difference in the doses to the other cardiac substructures in both groups. Mean
dose to the right lung was significantly less in group A as compared to BCS, 0.31Gy vs. 0.64Gy, respectively (p = 0.027).
Mean dose to the opposite breast was 0.52Gy and 0.37Gy respectively.
Conclusion
Our study emphasizes the need for contouring the cardiac substructures
especially the distal LAD and Left circumflex artery. The hypofractionation
schedule with 26Gy in 5 fractions has shown benefit in reducing doses to these
cardiac substructures. There is a need for clinical studies to validate the
results.