About 1 of every 4 of breast cancers are HER2-positive. That means the cancer cells have more of the protein HER2. It causes these cells to grow and spread faster than the ones with normal levels of the protein.
This cancer is more aggressive than other types, but there are treatments to help. You’ll work together with your doctor to come up with a treatment plan that's best for you.
Researchers aren't sure what causes breast cancer. They think it may be a combination of things, including your genes, environment, and lifestyle. But genes don’t play the same role in HER2-positive cancer as they do with other kinds. You can't inherit a bad copy of this gene from a parent, and you won’t pass it on to your children.
The most common warning sign of any type of breast cancer is a lump in your breast that feels different from the area around it.