Abstract :Breast cancer presents great heterogeneity in its findings. We aim to analyze suspicious breast nodules by echographic study for breast cancer, evaluating the accuracy and inter-observer agreement in the BI-RADS 4A, 4B, 4C, and 5 classifications. Of the 70 patients selected for a prospective study, 40 confirmed positive for malignancy. Among the various ranges of classification for category 4, no patient classified with category 4A nodules showed malignancy, 28.6% showed for category 4B, and 75.0% and 96.3% for categories 4C and 5, respectively. The agreement rates resulted in the Kappa of 0.896. Area under the curve for BI-RADS categories was 0.939 (CI 95%, 0.85 to 0.98), p=0.0001. Category 4C was the best accuracy point, with sensitivity 92.5% and specificity 83.3%. Category 4C was characterized as having higher accuracy for breast cancer diagnosis, having shown good agreement among different researchers when the objective criteria were meticulously applied.