Lymphedema, secondary to breast cancer (BCRL), is the abnormal accumulation of protein-rich fluid in the interstitium caused by a malfunction of the lymphatic system. It causes swelling, deficiencies in upper limb functions and structures, sensory pain and emotional alterations, which have a chronic course and affect the upper limb's functionality. This study aims to verify the efficacy and efficiency in the upper limb´s functionality of a protocolized experimental approach based on occupational therapy, TAPA (activity-oriented proprioceptive antiedema therapy), in the rehabilitation of BCRL in stages I and II, comparing it with the conservative treatment considered as the standard, complex decongestive therapy (CDT), through a multicenter randomized clinical trial. a randomized and prospective clinical trial was conducted with experimental and control groups. Women diagnosed with BCRL belonging to institutions in Córdoba and Aragon (Spain) participated. Sociodemographic variables and those related to the functionality of the affected upper limb were evaluated before and after the intervention. The results showed statistically significant differences in the analysis of covariance performed for the variable joint balance of the shoulder´s external rotation ( = 0.045) that could be attributed to the intervention performed; however, the effect size was minimal (η ≤ 0.080). In the rest of the variables, no significant differences were found. TAPA may be an alternative to the conservative treatment of women with BCRL. It was shown to be just as effective for volume reduction and activity performance as CDT but more effective in improving external rotation in shoulder joint balance.