ESTRO 2024 - Abstract Book

S687

Clinical - Breast

ESTRO 2024

Significant alterations in the metabolome of BC patients were observed compared to a control group before treatment, and after oncological therapies these metabolites were normalized. The potential biomarkers identified are hypoxanthine, 3-phosphoglyceric acid, maltose, xylonic acid, and dodecanoic acid. We also identified differential metabolites between peritumoral and tumoral tissue in analyzing tissue samples. This discovery underscores the metabolic disturbances tumor cells induce within the local tumor microenvironment, shedding light on their potential implications in disease progression and treatment response. Our findings not only shed light on the potential diagnostic and prognostic value of these metabolites, but also highlight the significant impact of oncological treatments on the metabolites landscape of BC patients.

*This research was funded by VARIAN, a research grant 2020-21. The funders had no role in study design, data collection and analysis, publication decisions, or manuscript preparation.

Keywords: Biomarkers, surgery, cell metabolism

2855

Digital Poster

Link between extent of acute breast skin dermatitis and radiation dose following proton therapy.

Nicolas Depauw, Katherine Santoro, Meredith Taylor, Erin Plummer, Alphonse Taghian, Rachel B Jimenez

Massachusetts General Hospital, Radiation Oncology, Boston, USA

Purpose/Objective:

Dermatitis is the most common side effect experienced by patients with breast cancer who receive radiation therapy (Liang et al., 2018). Proton therapy has been increasingly used in the treatment of breast cancer, and studies have shown variable reports regarding the severity of dermatitis observed with proton therapy (Fellin et al., 2019). Herein, we evaluate the association between acute clinical dermatitis and skin dosimetric parameters among a prospective cohort of patients with breast cancer who received proton therapy.

Material/Methods:

Acute skin dermatitis was assessed prospectively, at baseline (pre-radiation) and at the completion of radiation therapy, using both multi-angle photography and physician-reported assessments via the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 (grade 1 = faint erythema or dry desquamation, grade 2 = moderate erythema, patchy moist desquamation, and moderate edema and grade 3 = severe erythema or moist desquamation in areas other than skin folds and creases, and bleeding). Radiation therapy consisted of either breast or chestwall radiation plus regional nodal irradiation delivered with pencil beam scanning proton therapy. Target prescriptions ranged from 50 to 60 GyRBE (RBE=1.1) in 1.8 to 2 GyRBE per fraction. For each patient, a skin rind structure was generated based on a 3 mm rind inside the skin contour but expanding no further than 3 cm laterally from the combined treatment target to ensure that only the skin within and around the treatment field was evaluated. Preliminary results were generated based on ten cases. The dose received by 10 cc