Chemotherapy treatments such as epirubicin-cyclophosphamid or paclitaxel lead to severe off-target side effects such as skeletal muscle deconditioning. Resulting from a global perturbation of the muscle homeostasis, skeletal muscle is characterized by both structural and functional alterations that will translate into a decrease in muscle mass and/or force as well as an increase in muscle fatigability. These maladaptations result in a reduced quality of life and an increased treatment-related toxicity, ultimately leading to an increased mortality risk.To date, three different studies investigated skeletal muscle decontioning in breast cancer patients, through long term protocols including all chemotherapy cycle treatment, and highlighted both structural alterations and impaired cellular processes. However, no study is currently availbale on the acute effect of one single chemotherapy administration in breast cancer patients skeletal muscle tissue.Our study is therefore dedicated to the investigation of the acute effect of the first dose administration of both Epuribicin/cyclophosphamide and Paclitaxel chemotherapies on skeletal muscle of breast cancer patients. Our study will particularly explore cellular mechanisms of muscle decontioning, such as protein turnover, mitochondrial homeostasis and fatty infiltrations.
