expression of anaplastic lymphoma kinase protein in human breast cancer

background &amp; objectives: anaplastic lymphoma kinase (alk) is a receptor tyrosine kinase involved in the genesis of several human cancers. alk was initially identified because of its involvement in anaplastic large cell lymphoma (alcl). alk is believed to foster tumorigenesis following activation by autocrine and/or paracrine growth loops. studies reveal that the presence of anti-alk antibodies may be relevant to the relatively good prognosis. therapeutic approaches consisting of gene therapy and immunotherapy targeting this molecule hold promise. material &amp; methods: we examined a number of human breast cancers to see if alk is expressed in this tumor and studied its relation with type of carcinoma and its grade, tumor size, presence of necrosis, vascular invasion , skin involvement, lymph node metastasis and patient’s age.  result: 100 patients were enrolled with mean age of 50.2 ± 12.5 years. the histological phenotypes of the breast cancers studied included invasive ductal carcinoma, invasive lobular carcinoma and medullary carcinoma. alk expression was evaluated by immunohistochemistry which was positive in 47 cases (47%). no statistically significant relationship is found between the above mentioned parameters except for tumor size and alk expression. (p< 0.01)