<prompt> HER-2 neu receptor play a role in aEURPredicting therapeutic responseDetermining treatment for recurrence of tumorDiagnosis of breast CaScreening of breast Ca  <response>: Predicting therapeutic response Overexpression of HER-2neu in Breast cancer patients is associated with poor prognosis and increases disease recurrence. Overexpression HER-2neu also predicts good response to herceptin but is not a good predictor of response to chemotherapy and overall survival. Because of its prognostic role as well as its ability to predict response to Herceptin transtuzumab breast cancers are routinely checked for overexpression of HER-2neu. HER-2neu erh-B, stands for Human e i idermal rowth factor rece i tor. It is a molecule present in small amounts on the surface of ceain types of cells such as breast cells and ovarian cells. HER-2 belongs to Erb protein family commonly known as epidermal growth factor receptor family EGFR. - The epidermal growth factor receptor are present on the cell surface and are involved in the signal transduction pathways leading to cell growth and differentiation. Activation of epidermal growth receptor EGFR Ligand binds to the EGFR Dimerisation of EGFR Activation of EGFR vir Signal transduction to nucleus Jr Cell growth and differentiation Although HER-2 is highly hontologus to EGFR, it does not have any specific ligand for it. Therefore it is also called orphan receptor. - Instead of activation by direct ligand binding it exhibits constitutive activity in the absence of ligand. The constitutive activity of the HER-2 is increased by overexpression of HER-2. - The most common mechanism by which HER-2 gets activated and transforms cells is by overexpression of normal HER-2. This phenomenon is observed in breast cancers. There are ceain types of breast cancers that overexpress HER-2neu receptors on their surfaces. - In 1 out of every 5 breast cancers the cancer cells make an excess of HER-2neu. - HER-2 positive breast cancers tend to be more aggressive than other types of breast cancer. - Overexpression of this receptor in breast cancer is associated with increased disease recurrence and worse prognosis. - They are also less responsive to hormone treatment However drugs that specifically target HER-2 are very effective. -Herceptin Transtuzumb is a drug that specifically targets HER-2 receptors and blocks their action. - Herceptin or transtuzumab is approved for HER-2neu overexpressing breast cancer. Because of its prognostic role as well as it ability to predict response to Herceptin transtuzumab breast cancers are routinely checked for overexpression of HER2Inett. 