52P - A comparative study to assess volumetric and dosimetric profile of heart and lung in patients undergoing left sided post mastectomy radiotherapy: Continuous positive airway pressure (CPAP) versus free breathing (FB) techniques

Background

Post mastectomy adjuvant radiotherapy (RT) is a critical part in management of breast cancers. Left sided breast cancer cases are at higher risk of developing radiation induced cardiac morbidities. Increased radiation dose to the heart and lung may cause non-breast cancer related mortality and reduce the survival benefits from breast cancer RT. We designed a prospective clinical trial to examine the impact of CPAP on heart and lung during left sided post mastectomy radiotherapy.

Methods

24 left sided post mastectomy patients, after prior consent were included in this study. All patients were simulated in free breathing technique, followed by using CPAP (target pressure 10 to 15 cm of H20). Contouring was done using RTOG guideline. Heart and lung volumes were noted. IMRT virtual plans for both of these techniques were made for all patients using Monaco 5.51.10 software. Mean heart dose, Heart V25, Ipsilateral Lung mean dose, V5, V10, V20 were measured. Mean ± Std values were assessed using Students’ t-test.

Results

Compared to FB, CPAP showed significant difference. Mean heart distance from sternal notch was 6.2 cm and 7.2 cm ;p Value: 0.032 and Mean heart volumes were 354cc and 387cc in the CPAP and FB arms respectively;pValue: 0.665 . Mean left lung volumes were 1281 cc and 1398 cc respectively ;pValue 0.038 favouring CPAP arm. Similarly mean right lung volume of 1552 cc was significantly higher in CPAP arm compared to 1178 cc in FB arm (pValue : 0.041). Heart Dmean was found to be statistically better in CPAP arm (2.5 Gy) compared to FB arm (3.4 Gy) (p Value 0.020). Average V25 of heart was significantly superior in CPAP arm compared to FB arm (0.23% and 2.24% respectively,p Value 0.035). Heart Dmean was 3.1 Gy in CPAP arm compared to 3.7 Gy in FB arm ,pValue: 0.677. Similar result was found for heart V25. CPAP and FB Ipsilateral lung mean dose (6.69Gy and 6.32Gy, pValue: 0.62), Lung V5 (29% and 27.3%, p Value: 0.77), Lung V10 (16.3% and 16.4%, pValue: 0.78), Lung V20 (11.2% and 11.89%, p value 0.22) didn’t show statistical difference.

Conclusions

CPAP is an excellent tool for cardiac sparing in left sided post mastectomy breast cancer cases.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The author.

Funding

Has not received any funding.

Disclosure

The author has declared no conflicts of interest.