Abstract Background: Research indicates that up to two-thirds of patients with early breast cancer experience arm or shoulder pain or other symptoms following surgery and radiotherapy. The relationship between morbidity and dose administered to the humeral head is still not fully understood. We seek to determine if the radiation dose to humeral head, radiation technique (3D-CRT versus IMRT/VMAT), and fractionation schedule—correlates with the patient-reported outcomes measures (PROMs). Methods: We identified patients who underwent surgery and postoperative radiation therapy for early breast cancer and were included in the institutional prospective database of the Early Individualized Integrated Rehabilitation Program - OREH between November 2019 and April 2023. These patients had completed the EORTC QLQ-C30 and BR23 questionnaires prior to surgery/at baseline and 12 months after the start of treatment. Retrospective delineations of the humeral head and humeral head PRV with a 1 cm safety margin were implemented for each case. The treatment planning parameters for all treatment plans were subsequently obtained. The associations between categorical variables were investigated using Pearson's chi-square test and multivariate analysis. A two-tailed test was used to identify significant differences with a p-value of ≤0.05. The mean values were compared using the non-parametric Kruskal-Wallis test. Results: We enrolled 298 patients in this study. The majority of patients were treated with breast conserving surgery (N=210; 70.5%) and sentinel lymph node biopsy (N=200; 67.1%). The majority of patients (N=194, 65.1%) underwent moderate hypofractionation consisting of 15-16 fractions of 2,67 Gy with or without tumor bed boost. Regional nodal irradiation (RNI) to levels I-IV with or without internal mammary lymph nodes irradiation was delivered to 121 (40.6%) patients. Any pain in arm or shoulder was reported by 110 (36.9%) and 189 (63.4%) patients at baseline and 12 months after treatment start, respectively. Median Dmean doses to humeral head and humeral head PRV were 2.3 Gy (range 0-33.9 Gy) and 3.6 Gy (range 0-30 Gy), respectively. Multivariate ordinal regression model analysis confirmed a statistically significant association between the dose received by 2% of the humeral (D2%) (p=0.044), volume of humeral head receiving ≥10 Gy (V10Gy) (p=0.028) and V20 Gy (p=0.045) and any pain in arm or shoulder 12 months after diagnosis. At baseline and 12 months after treatment initiation, 39 (13.1%) and 142 (47.7%) patients, respectively, reported any difficulties in raising or moving their arm sideways. This was correlated with humeral head V20 Gy (p=0.029) and V30 Gy (0.035) in a multivariate analysis. Irradiation to lymph node regions, radiation technique (3D-CRT versus IMRT/VMAT), fractionation schedule (hypofractionation versus conventional fractionation), type of breast and axillary surgery were not correlated with arm or shoulder pain (or other symptoms) and PROMs. Conclusions: The irradiation of the humeral head correlates with the development of arm or shoulder symptoms following surgery and radiotherapy for early breast cancer. More research is needed toward identifying dose to organs at risk that will be considered when planning future radiation therapy. Citation Format: T. Jarm, N. Besic, R. Cencelj Arnez, J. But Hadzic, I. Ratosa. Evaluation of radiation exposure to the humeral head and its correlation with patient-reported outcomes in patients undergoing radiotherapy for early breast cancer abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PD12-08.
Jarm et al. (Tue,) studied this question.