Abstract P4-12-31: Oncoplastic surgery and the influence of the surgical clip on breast, heart and lung volumes of patients submitted to boost during the planning of breast cancer radiotherapy after lumpectomy

Abstract

Abstract Objectives: To evaluate the breast, heart and lung irradiated volumes considering the presence of clip implantation in breast tumor bed boost during the radiotherapy, after lumpectomy according to the use of oncoplastic surgery. Methodology: Retrospective study of womens submitted to boost radiotherapy tumor bed after breast conservative surgery for breast cancer between january/2011 and april/2018. Statistical analysis using Student T Test (95%CI; p<0,05). It was considered volumes of lung and heart relative to 40% of prescribed dose in the boost radiation planning (V40 Lung) (V40 Heart) and 100% in the breast and boost volume (V100 Breast) (V100 Boost), which were compared by different oncoplastic techniques and surgical clips using the dose-volume histogram (DVH) in three-dimensional conformal radiotherapy (3DRT). Results: This study evaluated 149 patients, 71 womens had clip (48%) and 69 patients submitted to oncoplastic surgery (46%), and among these 38 had clip in the surgical bed (55%). For the whole group, when the patient was clipped there was a difference between the mean volume V100 Boost=110 cm3 (SD±37) and without clip V100 Boost=213 cm3 (SD±208) p<0.001, but there was no difference for V100 Breast=282 cm³ with clip (SD±141) and without clip V100 Breast=400 cm3 (SD ± 188) p=0.085, nor for V40 Lung=57 cm3 (SD±41) with clip and 43 cm3 (SD±47) p=0.72 without clip and V40 Heart=2.40 cm3 (SD±6) with clip and 2.78 cm3 (SD±14) p=0.59 without clip. For those who underwent oncoplasty, there was no difference between the means of the volumes analyzed according to the presence of the clip. However, for those who did not undergo oncoplasty only the V40 Lung was not significant for the presence of the clip (p=0.28), but were significant for V100 Boost=111 cm3 (SD±35) with clip and 262 cm3 (SD±274) without clip (p<0.001), V100 Breast=306 cm³ (SD±147) with clip and 423 cm3 (SD±218) without clip (p=0.002) and V40 Heart=2.02 cm3 (SD±4) with clip and 0.62 cm3 (SD±2) without clip (p=0.009). The most common oncoplastic techniques used were reduction mammoplasty (volume reduction in cases of large breast) in 41 patients (59%) and round block in 9 (13%), only 4 patients (5.7%) aumentation mammoplasty and 2 (2.8%) remodeling surgery. Conclusion: The presence of the clip reduced significantly the irradiated boost volume. When controlled by oncoplasty, there was no difference between the two groups. For those who did not undergo oncoplastic surgery, the presence of the clip made it possible to reduce the irradiated volume that received 100% of the prescribed dose of the whole breast and the boost area, and the increased cardiac volume that received 40% of the prescribed dose during the radiotherapy boost planning deserves further analysis. Keywords: breast cancer, radiotherapy, boost, surgical clip tumor bed, oncoplastic techniques Citation Format: Nilceana MA Freitas, Priscila D Watanabe, Thais F Simionatto, Nathalya A Yagi, Ana FPG Campedelli, Edesio Martins, Marcus N Borges, Ruffo Freitas-Junior. Oncoplastic surgery and the influence of the surgical clip on breast, heart and lung volumes of patients submitted to boost during the planning of breast cancer radiotherapy after lumpectomy [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-12-31.