The study of mucins has expanded dramatically as their structure has been elucidated and it has become clear that they play crucial roles in normal physiology and in disease. The characterization of different mucins and the cells which produce them led to the documentation of their expression, not only in normal tissues, but also in many types of cancer, where increased levels of expression can be seen. As a consequence, cell surface mucins have become targets for cancer therapy and have found application as tumor markers. The nine chapters of this book explore the various forms of involvement and variation of mucins in cancer. This overview will encourage further the increasing numbers of collaborations we now see between glycobiologists and clinicians in translational research toward clinical applications of mucin research in cancer management.