Whether it is important to have breast duct expansion of 1.6mm needs to be judged according to the causes leading to the expansion of breast ducts. If the expansion is caused by benign lesions, it is usually not very serious; if the expansion is caused by malignant tumors, it is necessary to actively take surgical treatment. 1. Benign diseases: caused by breast duct drainage disorder, inflammation and infection, breast hyperplasia, mostly seen in women aged 40~60, usually patients have no self-conscious symptoms, and some patients show increased ductal secretion, nipple overflow, and lump under areola. 2. Malignant diseases: breast duct expansion caused by breast malignant tumor, eczema-like breast cancer is more important, requiring timely surgical treatment, combined with radiotherapy, endocrine targeted therapy and other treatments. If the dilatation of breast ducts persists or affects your life, you should go to the hospital for timely examination and treatment under the guidance of your doctor.