Risk factors for arm lymphedema following breast cancer surgery: a Japanese nationwide database study of 84,022 patients

Although arm lymphedema is a well-known complication following breast cancer surgery, previous studies involving a small population showed inconsistent results regarding the risk. Therefore, we examined the risk factors using a Japanese nationwide database.Female patients who underwent breast cancer surgery from April, 2016, to March, 2020, were identified from a Japanese nationwide database. Multivariable survival analyses for 19 baseline factors (12 patient characteristics, four tumor characteristics, and three surgical procedures) were conducted to investigate risk factors associated with treatments for postoperative lymphedema (such as lymphatic bypass, compositive drainage therapy, hospitalization, and Kampo use) with a multilevel model to adjust for within-hospital clustering. We also conducted multivariable analysis for five postoperative factors (two local complications and three postoperative therapies) with adjustment for 19 baseline factors.The study included 84,022 patients; 1547 (1.8%) received treatments for lymphedema during a median follow-up of 119 weeks (interquartile range, 59-187 weeks). Young age, obesity, smoking, collagen diseases, advanced cancer stage, total mastectomy, axillary dissection, postoperative bleeding, chemotherapy, and radiotherapy were identified as risk factors. Postoperative chemotherapy (hazard ratio, 3.78 [95% confidence interval, 3.35-4.26]) and axillary dissection (2.46 [1.95-3.11]) showed the highest odds ratio among the risk factors. The cumulative probabilities in high-risk patients reached approximately 3% at 1 year and 6% at 4 years after surgery.This study identified several risk factors for postoperative lymphedema in breast cancer surgery. The treatment initiation increased markedly within the first year and gradually after 1 year post-surgery.