Incidence and risk factors of breast cancer-related lymphedema in Korea: A nationwide retrospective cohort study.

BACKGROUND: Breast cancer-related lymphedema (BCRL) is a secondary lymphedema that occurs after breast cancer related treatments. BCRL develops from damage or dysfunction of the normally functioning lymphatic system due to surgery, radiation therapy and rarely due to cancer recurrence. This nationwide, retrospective study was aimed at investigating the incidence and risk factors of BCRL using the database of the Korean National Health Insurance Service (NHIS).

METHODS: Patients with newly diagnosed breast cancer who underwent breast surgery from January 1, 2017 to December 31, 2020, were recruited. The incidence was compared by four groups according to the operation type of breast cancer (breast conserving surgery (BCS) with sentinel lymph node biopsy (S), BCS with axillary lymph node dissection (A), total mastectomy (TM) with S, modified radical mastectomy(MRM)). The incidence rates of lymphedema were calculated by the number of incident events by the total follow-up period. Cox proportional hazard regression was used to calculate the risk of incidence of lymphedema based on a patients' characteristics, breast cancer treatment and comorbidities.

RESULTS: The final cohort of operation subjects that satisfied the inclusion criteria was 34,676. BCRL occurred in 4,242 patients (12.2%), and the median follow-up period was 695.4 days. The BCRL was diagnosed in the BCS with S (8.0%), BCS with A (23.5%), TM with S (10.7%), MRM (28.5%) with an incidence of 40.8, 132.2, 55.8 and 171.8 per 1,000 person-years, respectively. Young age, obesity, chemotherapy, radiotherapy, residence in metropolitan areas and hyperlipidemia were identified as risk factors.

CONCLUSION: In Korea, the incidence of BCRL was found to be 12.2%, with the highest risk observed among patients who underwent MRM. Therefore, surgical oncologists should meticulously assess the appropriate surgical approach and consider providing education to patients with risk factors for BCRL, aiming to ensure effective prevention strategies.