8. The dilemma of in situ carcinoma of the breast

Abstract

Both ductal cardinoma in situ (DCIS) and lobular carcinoma in situ (LCIS) are forerunners of invasive breast cancer but with different behaviour. Neither condition is fatal but management can be difficult. After 20 years follow-up of LCIS, the cumulative risk of ipsilateral invasive cancer is 18%, and 14% for contralateral disease. Of the cancers that occur, 40% are invasive lobular and 60% invasive ductal. Standard management of LCIS is surveillance, with no attempt to perform a wide excision or a mastectomy. Many cases of DCIS are detected because of microcalcification on mammograms; 20% of screen-detected cancers are of this type. DCIS is a forerunner of ipsilateral invasive disease, so complete excision is necessary. Subsequent relapse or progression to invasive disease can be reduced by breast irradiation. Because of the extent of DCIS, a significant proportion of patients will need a total mastectomy with or without immediate reconstruction.