2915 - Shoulder Function in Patients with Breast Cancer Treated with Proton Therapy
Presenter(s)
E. Augustin1, E. Viviers2, N. P. Mendenhall1, R. Mailhot Vega1, T. Burchianti2, and J. A. Bradley1; 1Department of Radiation Oncology, University of Florida College of Medicine, Jacksonville, FL, 2University of Florida Health Proton Therapy Institute, Jacksonville, FL
Purpose/Objective(s): Regional nodal irradiation (RNI) in breast cancer treatment can impact shoulder function due to radiation dose to periscapular muscles. This study evaluates the relationship between muscle group dose and patient-reported shoulder function using the Disabilities of the Arm, Shoulder, and Hand Questionnaire (DASH-Q).
Materials/Methods: Forty-nine adult female patients with breast cancer treated with RNI using proton therapy were analyzed. Shoulder function was assessed using DASH-Q scores (maximum post-radiation impairment over time). Dosimetric data, including mean and maximum doses to scapular, deltoid, and pectoral muscles, and the humeral joint, were extracted. Mean and maximum dose to all muscle groups were also evaluated. Correlations between muscle dose and DASH-Q scores were analyzed using techniques such as descriptive and Spearman’s rank correlational.
Results: The median patient age was 55 years (range, 25-81), with a median follow-up of 56 months (range, 26-83). Median prescription dose to the breast/chest wall and regional lymphatics (level I-III axilla, supraclavicular and internal mammary nodes) was 50 Gy in 25 fractions. The median maximum dose to the humoral joint was 47.3 Gy (range, 3.56-65.15), with a median mean dose of 10.66 Gy (range, 0.002-32.90). The median maximum dose to the periscapular muscle group was 57.7 Gy (range, 43.28-71.21) and a median mean dose of 12.2 Gy (range, 4.62-19.06). Forty patients had functional outcomes reported using the DASH-Q questionnaire, with a median score of 2.1 and a mean score of 14.8 (range, 0-50). Twenty-three patients (58%) had a score of 10 or less. Older patients demonstrated higher baseline DASH-Q scores, indicating greater pre-treatment shoulder dysfunction. No significant differences were observed between shoulder function and mean dose to periscapular muscles or the humeral joint.
Conclusion: Patients treated with proton therapy to the regional lymphatics reported high levels of post-treatment arm/shoulder function as measured by the DASH-Q patient-reported outcome tool. A correlation between shoulder muscle dose and shoulder function was not identified in this initial cohort analysis. Future work will expand the size of the cohort and assess the impact of other variables such as extent of axillary surgery, receipt of physical therapy, baseline function and lymphedema.