The causes of cancer are diversified. Cancer is the principal reason of death in the majority of countries and it results in enormous financial, societal and mental burden. Breast cancer is the most diagnosed kind of cancer and the foremost reason of death due to cancer amongst women. This book deals with various aspects of breast cancer. It discusses topics related to breast cancer cell lines, classification of tumors and stem cells. It also elucidates the microenvironment of breast cancer. It intends to help students and experts in gaining more knowledge regarding the topic.