Abstract: To investigate the activation of leukocyte adhesion molecule ( ALCAM ) in breast cancer and the relationship between the prognosis and its clinicopathologic characteristics. Methods: Up to 150 breast cancer patients were included in the study. The patients all underwent parallel modified radical mastectomy. Immunohistochemical staining and Western blot analysis were used to detect the ALCAM protein content, and different clinical and pathologic features in cases of differential expression were explored. Results: ALCAM was highly expressed in breast cancer tissues. Patients with high ALCAM expression in the cell membrane had a higher incidence of lymph node metastasis ( χ2 = 15.910, P = 0.010 ) and distant metastasis ( χ2 = 5.211, P = 0.029 ). High cytoplasmic ALCAM expression was correlated with local recurrence ( χ2 = 7.379, P = 0.012), especially short-term recurrence ( <2 years ) ( χ2 = 5.562, P = 0.037 ), but the long-term ( >2 years ) local recurrence was not significantly different. ALCAM protein expression was not correlated with ER protein expression ( P = 0.024 ). High cytoplasmic ALCAM staining intensity in patients was associated with low disease-free survival ( P = 0.036 ). Conclusion: ALCAM is highly expressed in breast cancer. High ALCAM expression on the cell membrane may weaken the adhesion of tumor cells, and promote tumor metastasis. However, the ectopic positioning of cytoplasmic ALCAM enhances tumor invasion, thereby, contributing to tumor development.