Multicentric and multifocal versus unifocal breast cancer: is the tumor-node-metastasis classification justified?

For classification of breast cancer (BC), tumor-node-metastasis (TNM) staging has been considered state of the art for more than 50 years. The T category is well defined, and in multicentric and multifocal tumors, tumor size is assessed by the largest tumor focus. The aim of this study was to compare multicentric/multifocal tumor spread in breast cancer with unifocal disease and to evaluate the diagnostic relevance of multifocality.