Lymphedema after regional nodal irradiation for breast cancer: a retrospective cohort study.

Purpose: We aimed to analyze the occurrence of lymphedema as a side effect in patients who underwent regional nodal irradiation (RNI) following surgery for breast cancer.

Methods: This retrospective study was conducted on patients with breast cancer who underwent surgery from July 2014 to October 2020 at Inje University Busan Paik Hospital. The analysis included 113 cT1-3N1-3M0 breast cancer patients who underwent RNI as part of radiotherapy (RT). Mostly, surgeries were performed using breast-conserving surgery (n = 99, 87.6%), except for 14 patients with modified radical mastectomy. The total RT dose for RNI was 45-60 Gy, and the fraction size was 1.8-2.0 Gy. Most patients underwent chemotherapy (n = 98, 86.7%), including taxanes (n = 92, 81.4%).

Results: The median follow-up was 61.1 months (range, 5.0-110.5 months). Lymphedema occurred in 54 patients (47.8%) after surgery. Twenty of them (17.7%) developed a new onset of lymphedema after RT, while 34 (30.1%) detected lymphedema before the completion of RT. Over the follow-up, 16 patients (14.2%) experienced recurrence. High radiation dose (>50.4 Gy) for RNI (P = 0.003) and taxane use (P = 0.038) were related to lymphedema occurrence after RT. Moreover, lymphedema occurrence after RT was also related to recurrence after surgical resection (P = 0.026). Breast-conserving surgery was related to early-onset lymphedema before the completion of RT (P = 0.047). Furthermore, the degree of lymph node dissection (≤4) was related to the overall occurrence of lymphedema (P = 0.045).

Conclusion: Considering a reduction in RNI dose may be beneficial in mitigating the incidence of lymphedema after RT in patients with breast cancer.