PURPOSE: In clinical practice, noticeable differences are seen in patient response to the treatment of breast cancer-related lymphedema. Although some factors influencing response to treatment are mentioned in the literature, there is no sufficient evidence and results are confusing. For this reason, our objective in this study is to identify predictive and response-related factors for response to treatment of breast cancer-related lymphedema. METHODS: We analyzed data retrospectively from the files of patients with breast cancer-related lymphedema between 2006 and 2012. Patient demographics, clinical variables, and patient variables were recorded. Circumference measurements of lymphedema and healthy arms were recorded. We used a computer program (Limb Volumes Professional version 5.0) to transform these values to limb volumes in milliliters. RESULTS: The average age of 331 patients was 54.4 ± 10.9. The average length of lymphedema treatment was 2.92 ± 1.3 weeks. A statistically significant positive correlation was found between postoperative weight gain and postoperative duration, number of chemotherapy (CT) cycles, duration of tamoxifen use, and duration of hormonal therapy (p < 0.05). There was a statistically significant negative correlation between posttreatment arm volume and activity level, postoperative duration, and postoperative weight gain (p < 0.05). CONCLUSION: The treatment methods used for treating breast cancer had no effect on the response to treatment of lymphedema. Weight gain during the treatment of breast cancer is important for both the development of lymphedema and the response to treatment. When treating breast cancer-related lymphedema, the relationship between activity level and postoperative weight gain may provide us guidance in clinical practice.