Breast cancer is the most common cause of cancer death in women worldwide. In 2018, there were approximately 2.1 million women diagnosed with breast cancer. Most of the breast cancers are invasive making up about 80% and here cancer cells starts in glands and ducts, break through the walls and grown into breast tissue. The most common type of invasive breast cancer is invasive ductal carcinoma (IDC) followed by invasive lobular carcinoma (ILC). Detection of early invasive breast cancer is really important as survival of patient increases when the cancer is 2 cm or smaller. Women with early stage invasive breast cancer will have to undergo certain types of surgeries, and even some treatments like chemotherapy, radiation therapy, hormone therapy or targeted therapy to reduce the risk of recurrence. This chapter will give an overview about breast cancer, risk factors, stages of breast cancer, invasive breast cancer and its types and will discuss about diagnosis, treatments and markers for invasive breast cancer.