Which breast cancer type is characterized as ER positive?

The type of breast cancer that is characterized as ER positive is ductal carcinoma in situ. This refers to breast cancer that involves the ducts of the breast but is non-invasive, meaning it has not spread outside the ducts. It is known to express estrogen receptors (ER), which makes it sensitive to hormonal therapies that target these receptors.

HER2 positive breast cancer, on the other hand, refers to cancers that overexpress the HER2 protein and may or may not be ER positive. Triple negative breast cancer does not express estrogen receptors, progesterone receptors, or HER2, making it a different category altogether. Inflammatory breast cancer is also not specifically characterized by being ER positive, as it is a rare and aggressive form that can vary in receptor status.

Thus, ductal carcinoma in situ is recognized for its ER positive characteristic, indicating potential response to treatments that target these hormonal pathways.