Résumé
Abstract Background: One of the main adverse reactions of adjuvant radiotherapy for breast cancer is radiodermatitis. Objective: To assess the incidence of radiodermatitis in women with breast cancer, identify factors associated with its severity and determine the time at which this event occurs. Methods: Prospective cohort study in 113 women with breast cancer who were evaluated before radiotherapy and at every fifth session until the end of treatment. Logistic regression and Cox proportional regression model were used for the assessment of risk factors; P values < 0.05 were considered significant. Results: The incidence rate of radiodermatitis was 98.2% and it was demonstrated that for each additional point of the Body Mass Index (BMI), the chance of occurrence of grades II to IV radiodermatitis increases by 14% (OR = 1.14 [95% CI 1.04-1.26]; p = 0.004) and statin use increases the risk of more severe skin lesions by four-fold (OR = 4.27 [95% CI 1.11-16.42]; p = 0.035). The exclusive use of hydrogel for skin hydration was an independent factor in delaying the onset of radiodermatitis (HR = 0.55 [95% CI 0.36-0.82]; p = 0.004). Study limitations: The main limitation of this study was its external validity. The identified factors should be considered for services and populations similar to those in this study. Conclusions: There was a high incidence of radiodermatitis and its severity was related to higher BMI, statin use; there was a protective effect of hydrogel use.