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

Abstract 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.