HER2/neu test

A laboratory test that measures the amount of HER2/neu protein on cancer cells or how many copies of the HER2/neu gene are in the DNA of cancer cells. The HER2/neu protein helps control normal cell growth. Larger than normal amounts of the HER2/neu protein or too many copies of the HER2/neu gene may be made by some types of cancer, including breast, ovarian, bladder, pancreatic, and stomach cancers. This may cause cancer cells to grow more quickly and spread to other parts of the body. A HER2/neu test may be done to help plan treatment, which may include drugs that target the HER2/neu protein. It is a type of tumor marker test. Also called HER2 test and human epidermal growth factor receptor 2 test.