Background: antineoplastic treatment for locally advanced breast cancer (LABC) includes neodjuvant chemotherapy (NeoCT). However, side effects occur frequently, affecting the functional capacity and quality of life of patients as a result of the proinflammatory state of this therapy. In this work, omega-3 polyunsaturated fatty acids (PUFA Ω-3) were administered as they have been reported to modulate some molecular pathways such as nuclear factor-kappa B (NF-κB), which is associated with toxicity secondary to the administration of anthracyclines. Objective: to evaluate the effects of PUFA Ω-3 on the toxicity, side effects, body composition, cardiometabolic profile and quality of life in women with LABC after NeoCT. Methods: fifty-three women with LABC were included in a double-blinded, placebo-controlled clinical trial. Patients randomly received 2.4 g/day of PUFA Ω-3 (EPA 1.6 g and DHA 0.8 g) or placebo during NeoCT with adriamycin/cyclophosphamide followed by paclitaxel+/-trastuzumab. Adverse effects related to chemotherapy were evaluated using the Common Terminology Criteria for Adverse Events (CTCAE, version 4.03) and the Subjective Global Scale of the Edmonton Symptom Assessment System (ESAS). Body composition and cardiometabolic blood profile were also evaluated. Results: no significant differences were found between groups in the hematological and anthropometric toxicity parameters. Within the Edmonton scale, xerostomia presented a significant improvement (p = 0.032) in patients supplemented with PUFA Ω-3. Conclusion: supplementation with PUFA Ω-3 showed no change in body composition, cardiometabolic profile or toxicity due to NeoCT. It only showed significant improvement in xerostomia.
