Ductal carcinoma in situ. Implications for screening mammography.

Ductal carcinoma in situ (DCIS) now represents 20% of all newly diagnosed breast cancers because of increased detection by screening mammography. Twenty year relative survival rates are 97%. Postsurgical and histological studies and recent molecular biological studies indicate that most cases of DCIS will progress to invasive carcinoma if not detected by mammography. Screening mammography studies support the need for annual versus less frequent screenings to detect DCIS before further progression.