LOBULAR CARCINOMA IN-SITU (LCIS) - PATHOLOGY AND TREATMENT

Lobular carcinoma in situ (LCIS) is not only a relative newcomer among breast lesions, but in its short span of 50 years it has gradually ev olved from a rare form of breast cancer to being merely a marker of in creased risk. This change has not been without controversy which persi sts to the present day, although there is now general agreement on the natural history of the disease. The present report represents an upda te on current thinking about LCIS as well as a review of the limited n umber of studies dealing with the natural history of the lesion when t reated by biopsy alone. Invasive cancer will develop in approximately 20-25% of women with LCIS provided there is sufficient follow-up after biopsy. Precise estimates are not possible since LCIS is an asymptoma tic lesion that never makes a mass or reveals itself on mammography. I t is found only by biopsy and thus the population being followed is a selected one. Every study has shown that when invasive cancer develops , it is just as likely to appear in the contralateral as in the biopsi ed breast, and invasive ductal cancers are more common than lobular. C learly, the small round cells with pale cytoplasm that characterize LC IS do not go on to invasion in the usual patient; rather they serve to identify women who are more likely to develop breast cancer. Such pat ients represent a clearly defined group at increased risk, and for tha t reason are ideal candidates for chemoprevention. If tamoxifen or som e other agent proves to be effective, the remaining arguments favoring mastectomy for LCIS will finally disappear. (C) 1993 Wiley-Liss, Inc.