Leukemoid Reaction as a "Tumor Marker" in Breast Cancer

Neutrophilic leukocytosis above 50 × 109/l exclude leukemia, defines a leukemoid reaction (LR). It is associated with several diseases. Although it simulates leukemia, most of the causes are benign. Tumor-related LR is more common. It is associated with ranulocyte colony-stimulating factor (G-CSF) secreted by the tumor cells. A 38-year-old woman, presented with advanced breast cancer and leukocytosis (79.9 × 103/uL) was found. After completion of MRM, the condition of leukocytosis subsided. Two months later, tumor local relapse was found and white blood cells (WBC) rose again. After completion of wide excision, the condition of leukocytosis subsided again. We think this case was associated with leukemoid reaction.