LAUSR

Introduction/Background To compare the risk of lower extremity lymphedema (LEL) between pelvic external beam radiation therapy (EBRT) and brachytherapy and to identify risk factors for LEL in gynecologic cancer patients treated with adjuvant radiation therapy (RT). Methodology International Federation of Gynecology and Obstetrics (FIGO) stage I-III gynecologic cancer patients who underwent adjuvant RT between January 2013 and December 2017 were retrospectively reviewed. Patients were diagnosed as LEL when the difference in leg circumference was 2 cm or more. One-to-one case-matched analysis was conducted with propensity scores generated from patient, tumor and treatment characteristics. Using the risk factors found in this study, high- and low-risk groups for LEL were identified. Results With a median follow-up of 30.6 months, 34 (13.5%) patients developed LEL. In the multivariate analysis, laparoscopic surgery (hazard ratio [HR], 2.548; p=0.025), harvesting more than 30 pelvic lymph nodes (HR, 2.167; p=0.037), and para-aortic lymph node dissection (PALND, HR, 2.537; p=0.009) were identified as independent risk factors for LEL. After propensity score matching, the EBRT group showed a significantly higher LEL rate than the brachytherapy group (3-year LEL rate: 30.3% vs 14.3%, p=0.034). The three-year LEL rate was 3.5 fold higher in the high-risk patient group (34.3% vs 9.8%). Conclusion Laparoscopic surgery, harvesting more than 30 pelvic lymph nodes, and PALND were risk factors for LEL in gynecologic cancer patients. Compared with brachytherapy, adjuvant pelvic EBRT was also associated with an increased risk of LEL. High-risk group patients with these risk factors require a closer observation for LEL. Disclosure Nothing to disclose Abstract EP1104 Figure 1 Cumulative incidence of lower extremity lymphedema (LEL) in the matched cohort according to modality Abstract EP1104 Figure 2 Cumulative incidence of lower extremity lymphedema (LEL) according to risk groups