The effect of biology in the treatment of small breast tumors.

Although the outcome of small (T1a/b) node-negative breast tumors is generally excellent, in the absence of prospective clinical trials, we are limited to data derived from retrospective analyses. Overall, the 10-year overall mortality rate is approximately 20%, while the 10-year breast cancer-specific mortality is in the range of 4% to 8% among this population in the absence of systemic therapy. This clearly reflects that many patients die of causes not related to breast cancer. Due in large part to breast cancer screening programs, the incidence of small tumors is increasing. There is consequently a growing interest in identifying factors that negatively affect the prognosis of these patients. Several studies have shown that patients with triple-negative and HER2+ tumors have a worse prognosis compared with hormone-receptor-positive, HER2- small breast cancers. However, the recent explosion of knowledge of the molecular characteristics of tumors is opening a new way to address cancer. Different genomic assays are currently available to help better predict the outcome of breast cancer patients. However, none of these techniques have been specifically evaluated in patients with small (T1a/b) node-negative tumors, and only a small number of patients with these tumors were included in those studies. In addition, very limited data are available about the role of these assays in patients with triple-negative or HER2-positive cancers. Although a chemotherapy-based strategy might be useful for triple-negative or HER2-positive T1b tumors, more information is urgently needed in order to optimize the treatment of our patients.