e24127 Background: The treatment for patients diagnosed with breast cancer is based, in the curative intent scenario, on chemotherapy (CT) such as anthracyclines and taxanes. We are aware that some drugs are widely used and necessary before CT administration to avoid unwanted side effects. Dexamethasone is part of the arsenal of these medications, however, pathological conditions resulting from high doses of administration of this corticosteroid are clinically evident in these patients. In this study we aim to evaluate whether omitting a dose of corticosteroid therapy as a premedication after the second week of treatment with taxane can prevent or reduce the incidence of metabolic changes, and its impact on a patient's quality of life (QoL). Methods: A prospective, randomized, open label study. Breast cancer patients with indication for adjuvant or neoadjuvant treatment with doxorubicin, cyclophosphamide and paclitaxel + trastuzumab (AC-T+ TTZ) chemotherapy were randomized to standard arm, with dexamethasone 10 mg IV administered pre-paclitaxel in all cycles and experimental arm, where dexamethasone was omitted from the premedication from the third to the last taxane application. Results: 86 patients were included, 43 patients in each arm. Premedication was administered every cycle and/ or week before the administration of chemotherapy drugs. Patients had lab analysis and QoL EORTC QLQ-C30 before the beginning of the CT, before the third application of Paclitaxel and 24 hours after the last administration. We observed an increase in ACTH in the experimental group, which is predictable since high doses of corticosteroids suppress the hormone pathway; a drop of insulin levels in its levels in the experimental group and stability in its serum levels in the control group; a stability of GH and IGF-1 in the control group and a more pronounced drop in circulating levels of this hormone in the experimental group. The control group had a greater increase in the excretion of aldosterone, probably due water retention caused by the use of dexamethasone. There were no adverse events reported in the experimental group and also hypersensitivity or anaphylactic reactions were not observed. The EORTC-QLQ-C30 scores related to diarrhea, constipation, inappetence and insomnia were better in the experimental group, as well the average score for global health. Conclusions: The omission of dexamethasone in patients in the experimental group improved QOL scores related to common AEs during CT, mainly GI and also insomnia. Insulin levels were also lower in this group. The potential reduction of the incidence of metabolic syndrome seems palusible but would require larger sample size. The short term safety and tolerability of this regimen warrants its use in larger populations. Clinical trial information: NCT04350229 .