Background Identification of risk factors is important for the prevention of Breast Cancer-Related Lymphedema (BCRL), and epidemiological large-scale studies are needed. Although database studies are suitable for large-scale surveys, there have been no studies using databases to investigate risk factors for BCRL. The purpose of this study was to test the hypothesis that database-based studies are useful in identifying risk factors for BCRL. Methods Patients diagnosed with breast cancer during a 10-year period from April 2009 to March 2020 were selected from the medical database of Hiroshima University Hospital. As a retrospective observational study, risk factors for BCRL were validated by logistic regression analysis (p < 0.05). Results A total of 4471 breast cancer patients were selected and 2359 met study criteria; the incidence of BCRL was 4.8%. Risk factors for BCRL ultimately identified by multivariate logistic regression analysis were obesity with BMI 25 to 30 (OR = 3.066, 95%CI: 1.408 ~ 6.677), severe obesity with BMI > 30 (OR = 5.791, 95%CI: 2.239 ~ 14.97), surgical axillary lymph node dissection (OR = 3.212, 95%CI: 1 .918 ~ 5.378), chemotherapy with docetaxel (OR = 1.795, 95%CI: 1.062 ~ 3.032), and conventional radiation to the breast or chest wall with lymph nodes in the irradiated area (OR = 3.299, 95%CI: 1.842 ~ 5.910). Conclusions The risk factors for BCRL identified in this study were generally similar to those in previous studies, indicating that database-based studies are useful for identifying risk factors for BCRL. A multicenter study involving a larger number of patients and study items needs to be conducted in order to more fully elucidate the risk factors for BCRL.