DCIS (ductal carcinoma in situ) is a precancer that is usually found on a mammogram

Ductal carcinoma in situ (DCIS) is a precancer that usually shows up as tiny clusters of white specks on a mammogram. The specks suggest there are abnormal cells inside a breast duct. There currently isn't a reliable way to tell whose DCIS has the potential to become an invasive breast cancer and whose does not. This is why doctors recommend women have surgery to remove the DCIS. Some women may also be treated with radiation and/or hormone therapy. Clinical trials are investigating whether watchful waiting may be a safe alternative for some women.