Abstract PS1-12: Factors associated with chronic breast lymphedema after adjuvant radiation in women undergoing breast conservation therapy
Authors: Rama Sanjay , Canella Cara , Luker Jenna , Park Kelley , Barry Renee , Ghosh Saheli , Zhu Simeng , Chen Yalei , Bensenhaver Jessica , Walker Eleanor , Levin Kenneth , Atisha Dunya , Evangelista Maristella 
Published: February 2021

Abstract
Purpose/Objective(s):Unlike temporary breast edema caused by post-lumpectomy radiation therapy (RT), the edema that persists beyond one year is not well defined and difficult to treat. The aim of this study is to define the incidence and risk factors for the development of chronic breast lymphedema in women undergoing lumpectomy with RT at a large metropolitan cancer center.
Materials/Methods:A retrospective chart review was performed on all patients who underwent lumpectomy from 2014 to 2018. Women who did not undergo RT at our institution and those with stage IV disease were excluded from the analysis. Patient demographics, comorbidities, operative data, RT data and postoperative complications were obtained. Chronic breast lymphedema (CBL) was defined as edema that persisted beyond one year post completion of radiation therapy. Breast volumes were determined by contoured breast volumes or, if unavailable, estimated by the 95% isodose volumes from the RT treatment planning system. Using a density curve, the distribution of breast volumes was plotted for patients with and patients without CBL. Univariate analysis was used to evaluate factors associated with CBL. Multivariate regression analysis was used to evaluate factors associated with the risk of CBL while accounting for potential confounding variables as defined by the univariate analysis.
Results:A total of 1173 patients were included for analysis. Seventy-four (6.3%) patients developed breast lymphedema beyond one year. For the entire cohort, mean age was 63 years old (SD=11.17), mean BMI was 31.15 kg/m2 (SD=7.17), mean breast volume was 1198.54 cm3 (SD=645.82 cm3), mean total radiation was 59.18 Gy (SD=16.76), and 139 (11.8%) patients underwent ALND. Compared to the cohort that did not develop CBL (n=1099), the CBL cohort (n=74) had a higher median BMI (33.23 kg/m2 vs. 29.81 kg/m2, P&lt;0.001), higher percentage of African Americans (56.8% vs. 37.9%, P=0.004), larger median breast volume (1502.33 cm3 vs. 1083.59 cm3, P&lt;0.001), higher percentage that underwent ALND (23% vs. 11.1%, P=0.005), and larger median size of lumpectomy specimen (128.00 cm3 vs. 94.57 cm3, P=0.002). When accounting for potential confounding variables, multivariate regression analysis revealed when breast volume was evaluated as a continuous variable, for every 1 cm3 increase in breast volume, the risk of breast lymphedema increases by 0.1% (OR=1.001, P&lt;0.001). When breast volume was analyzed as a categorical variable using 1300 cm3 as the optimal cutoff (based on density curve evaluations), patients whose breast volume was greater than 1300 cm3 had nearly 3 times the risk of developing CBL (OR=2.976, P&lt;0.001) compared to those with less than 1300 cm3 breast volume. The multivariate regression also demonstrated that CBL was associated with total radiation dose (OR=1.02, P=0.015) and African American race (OR=1.705, P=0.037).
Conclusion:Chronic breast lymphedema presents a clinical concern for women undergoing lumpectomy with postoperative radiation, particularly in women with larger breasts. Further studies should focus on preventative strategies, as well as the psychosocial and economic impact of this morbidity.
Citation Format: Sanjay Rama, Cara Canella, Jenna Luker, Kelley Park, Renee Barry, Saheli Ghosh, Simeng Zhu, Yalei Chen, Jessica Bensenhaver, Eleanor Walker, Kenneth Levin, Dunya Atisha, Maristella Evangelista. Factors associated with chronic breast lymphedema after adjuvant radiation in women undergoing breast conservation therapy [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS1-12.