CANTO skin: Evaluation of skin toxicity risk factors in patients treated for breast cancer.

Skin reaction is a common toxicity during oncology management, especially followed during the radiotherapy. Its assessment and understanding of the factors influencing its occurrence, is a major issue in the management of patients treated for an early breast cancer (BC). We evaluated 8561 patients during their overall management for a BC. We focus on specific skin toxicities: erythema, fibrosis, telangiectasia and changes of skin colour. These toxicities were assessed at the baseline defined as 0-3-6 (M0), 12 (M12), 36 (M36) and 60 (M60) months. The prevalence of toxicities of interest varied over time, so at M0, 30.4% of patients had erythema while 17.7% of patients had fibrosis. At M60, the prevalence of erythema was 2%, while fibrosis remained stable at about 19%. After adjustments, at M0, there was a significant association between the onset of cutaneous erythema and obesity, the presence of axillary dissection, the type of surgery and the tumour phenotype RH+/HER2+. Concerning fibrosis, a significant association was found, at M12, with the age of the patient, obesity, Charlson score and type of surgery. Concerning the modification of skin colour at M12, we find a link between the age of the patient, obesity, tobacco consumption and alcohol consumption. The prevention of this toxicity is a major issue for the quality of life. Our results allow us to understand the risk of developing skin toxicity in a patient, depending on her intrinsic, tumour or therapeutic characteristics and to implement adapted means of prevention and monitoring.