19P - Cardiac and lung sparing radiotherapy in breast and chest wall irradiation with surface guided radiotherapy using deep inspiratory breath hold technique

Background

Breast cancer is the commonest cancer among women requires multimodality treatment including adjuvant radiotherapy for better loco regional control. Long term toxicity to heart and lung following chemotherapy especially anthracyclines and Trastuzumab.Deep inspiratory breath-hold technique is a state of art technique for reducing heart doses without compromising target coverage or other organ-at-risk. The technique is based upon the observation that during inspiration, the flattening of the diaphragm and expansion of the lungs pulls the heart away from the chest wall. Surface guided radiotherapy (SGRT) is a magnificent devise helps us to do deliver and monitor radiotherapy with DIBH technique easily. This study explores the benefit of using DIBH with SGRT in left sided breast cancer radiotherapy treatment.

Methods

Eighty four breast cancer patients (both BCS and MRM), received adjuvant radiotherapy, between December 2019 and February 2022 were studied in this study. Patients were immobilized using breast boards with both arms positioned above the head. All patients had 2 sets of planning CT images (one in FB and another in DIBH) with a HD CT scanner in the same positional setup.Doses to the target and OARs and patient’s positional shits with three point laser and Align RT (VisionRT) surface guided RT were compared. The standard fractionation regimen of 50Gy in 25 fractions over a period of 5 weeks was used for all patients in this study.

Results

Among Eighty-four enrolled patients, average Dmean, V5%, V10%, V30% to heart with DIBH is 6.27 Gy, 33.04 GY, 19.49 Gy, 3.85Gy respectively. Average Dmean, V5%, V10%, V30% to heart with free breathing is 8.87Gy, 42.2 Gy, 29.9 Gy, 4.9Gy. which shows a statistically significant reduction in dose delivered to heart by using DIBH technique. Average dose to lung in terms of V30 Gy, V20Gy, V12Gy, V5Gy with DIBH is observed to be 24.38%, 28.9%, 36.51%, 48.98% respectively. While using FB technique lung doses in terms of V30 Gy, V20Gy, V12Gy, V5Gy with DIBH is observed to be 27.86%, 32.74, 37.58, 49.45 respectively.

Conclusions

Surface guided radiotherapy helps in precise positioning and patient monitoring which aims at more accurate treatment delivery.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Institutional Review Board.

Funding

Has not received any funding.

Disclosure

The author has declared no conflicts of interest.