Metastasis is the most lethal attribute of breast cancer and is responsible for majority of cancer related deaths. Numbers of metastasis suppressor genes that act to prevent or control metastasis have been identified in several types of cancers including breast cancer. This book is to analyze the association of genetic variations in metastasis suppressor genes with risk of breast cancer metastasis. A wide range of germ line mutations is described in different metastasis suppressor genes that can help in studying the important prognostic role of genetic changes in breast carcinogenesis and metastasis.