ESTRO 2024 - Abstract Book

S558

Clinical - Breast

ESTRO 2024

Keywords: oncologic outcome, toxicity, quality-of-life

1530

Digital Poster

Ultrasound Assessment of Breast Lymphedema Severity in Relation to Radiation Therapy

Amy T Le 1 , Thomas P Ahern 2 , Claudia B Perez 3 , Karen Ohara 3 , Michelle M Sowden 2 , Carl J Nelson 4 , Lisa Sanchez Johnsen 5 , Alison C Coogan 3 , Thomas Kim 1 1 Rush University Medical Center, Department of Radiation Oncology, Chicago, USA. 2 University of Vermont, Department of Surgery, Burlington, USA. 3 Rush University Medical Center, Department of Surgery, Chicago, USA. 4 University of Vermont, Department of Radiation Oncology, Burlington, USA. 5 Medical College of Wisconsin, Institute for Health and Equity, Milwaukee, USA

Purpose/Objective:

Breast lymphedema (BLE), defined as breast swelling caused by lymph fluid buildup, is a clinically significant adverse effect of breast conservation therapy. BLE is associated with an increased risk of infection, delayed wound healing, chronic pain, and diminished quality of life (QOL). No standardized, objective tool is available to diagnose and assess BLE, resulting in difficulty conducting etiologic research and tracking treatment response. As part of a more extensive pilot study, we sought to identify adjuvant radiation therapy characteristics that are associated with an increased risk of BLE.

Material/Methods:

We enrolled a prospective, observational study at a single academic institution. Data were collected from 28 patients (n=28) with unilateral breast cancer who underwent breast conserving surgery, sentinel lymph node biopsy, and radiation therapy 6 months to 2 years before their office visit. Subjects received partial breast, whole breast (WB), whole breast and axillary (WB+Ax), or whole breast and comprehensive nodal (WB+CNI) irradiation. We collected data on patient demographics, tumor characteristics, surgical parameters, and dosimetric radiation data. Dermal thickness measurements were taken via ultrasound (US) at the 6:00 position of both breasts; the difference between the dermal thickness measurements was used as a continuous measure of the extent of lymphedema. Based on data from healthy control patients, we used a between-breast difference in dermal thickness value of ≥0.5mm to define positive BLE status. The volume of the irradiated tissue at various dose levels was determined from the treatment plans e.g. V90%, V95% and V100%. Associations with dichotomous and continuous BLE were modeled with modified Poisson models and linear regression models, respectively.

Results:

Our pilot cohort was diverse (25% White/non-Hispanic, 21% Hispanic/Latina, 43% Black, 7.1% Asian, and 3.6% multiracial). Mean patient age was 59 years (range: 31 – 73), and 57% (n=16) had obese BMI. Twenty patients (80%) had tumor size <20mm, and 86% were node-negative. The mode for radiation prescription dose was 4,005 cGy