Breast Cancer-Specific Mortality in Small-Sized Tumor with Stage IV Breast Cancer: A Population-Based Study.

This study revealed that for stage IV breast cancer, smaller primary tumors were not always associated with better breast cancer-specific mortality. This study illustrated that very small triple-negative breast cancers (TNBCs) with extensive regional lymph node involvement may be a surrogate for biologically aggressive disease. Because of poor prognosis of T1a/T1bN2+ TNBCs, there might be an urgent need of more individualized treatment for affected patients. Future correlative studies ought to focus on the genetic and molecular differences in Ta1/T1bN2+ TNBCs that contribute to the biological behavior. Clarification of the regulation mechanism of very small-sized primary TNBCs with metastatic outgrowth in nodes and distant sites will play an integral role in developing targeted therapies.