Matig hypofractioneerde regionale klierbestraling bij borstkanker toont lage lymfoedeemincidentie en uitstekende ziektecontrole

PURPOSE: We conducted a prospective study to evaluate the incidence of upper extremity lymphedema following moderately hypofractionated regional nodal irradiation (MH-RNI) for breast cancer. We incorporated both standardized and expanded arm measurements to determine whether more granular assessment improves lymphedema detection. METHODS AND MATERIALS: This prospective, single-institution trial enrolled women with non-metastatic, lymph node-positive or high-risk node-negative invasive breast cancer following lumpectomy or mastectomy with an indication for RNI. Patients were stratified based on extent of axillary surgery: SLNB (≤5 nodes removed) versus ALND (>5 nodes removed). All patients received 42.56 Gy in 16 fractions to the breast/chest wall and regional lymphatics. The primary endpoint was cumulative incidence of clinically significant upper extremity lymphedema at 3 years. Lymphedema was assessed prospectively, using standard, 2-point circumferential measurements and additional exploratory circumferential measurements obtained at 10-cm intervals along the upper extremity. Competing-risk methods were used for lymphedema analysis, and Kaplan-Meier methods were used for time-to-event outcomes. RESULTS: Fifty-two patients were included; forty-one (78.8%) underwent SLNB, and eleven (21.2%) underwent ALND with a median (IQR) of 3 (2-4) and 10 (8.5-11.5) nodes removed, respectively. The cumulative incidence of lymphedema for all patients was 6.4% at 36 months; 5.7% following SLNB versus 9.1% following ALND (Gray's test p=0.62) with no additional events through 60 months. Additional 10-cm interval measurements did not detect lymphedema earlier than standard measurements or identify any additional cases. Acute and late side effects were predominantly grade 1-2, with no grade ≥3 late adverse events. No locoregional recurrences occurred. DMFS and PFS were 93.4% at 36 months and 87.9% at 60 months. OS was 97.2% at 36 and 60 months. CONCLUSIONS: MH-RNI was associated with a low incidence of upper extremity lymphedema, minor toxicity, and excellent intermediate-term disease control. Extended circumferential measurements did not improve detection of clinically significant lymphedema, supporting the adequacy of standard, two-point measurement techniques for clinical practice and future trials.