Ductal carcinoma in situ (DCIS) is the most common type of non-invasive breast cancer. Ductal means that the cancer starts inside the milk ducts, carcinoma refers to any cancer that begins in the skin or other tissues (including breast tissue) that cover or line the internal organs, and in situ means "in its original place." DCIS is called "non-invasive" because it hasn’t spread beyond the milk duct into any normal surrounding breast tissue. DCIS isn’t life-threatening, but having DCIS can increase the risk of developing an invasive breast cancer later on.
DCIS is often detected with mammographies but can rarely be felt. With the increasing use of screening mammography, noninvasive cancers are more frequently diagnosed and now constitute 15% to 20% of all breast cancers. Cases of DCIS have increased 5 fold between 1983 and 2003 in the United States due to the introduction of screening mammography. In 2009 about 62,000 cases were diagnosed.
Recently, an epidemiological survey of the detected DAVF cases in Japan between 1998 and 2002 was conducted. The detection rate of DAVF per 100,000 adults per year is 0.29 for DAVF. Furthermore, unlike Europe and North America where cases of transverse-sigmoid sinus DAVF are predominantly detected, in Japan, a higher number of cases of cavernous sinus lesions are detected, indicating racial difference in the presentation of DAVF.