LOBULAR NEOPLASIA - LONG-TERM RISK OF BREAST-CANCER AND RELATION TO OTHER FACTORS

BACKGROUND. Lobular neoplasia (LN), also known as lobular carcinoma in situ, is an incidental histologic finding in tissue removed at breast surgery. Patients with LN are known to be predisposed to develop inva sive or intraductal carcinoma (CA). This study investigates factors th at influence the cancer risk in LN patients. METHODS. Analysis of data concerning long term follow-up (median: 18 yrs) of 236 patients with LN identified in a pathologic review of more than 2000 biopsy specimen s with benign epithelial proliferative breast disease. RESULTS. The pr obability of CA developing in either breast in long term survivors aft er a biopsy that contained LN was approximately 1/3, which is 5.4 time s (95% CI: 4.2-7.0) the rate in the general population, The relative r isk (RR) tended to decrease with increasing age at diagnosis, but was approximately doubled (RR: 1.8; 95% CI: 1.1-3.2) for patients with ben ign epithelial breast disease preceding their initial diagnosis of LN. CA risk remained markedly elevated for at least 20 years, and increas ed substantially if there was a second operation showing LN-from 4.9 ( 95% CI: 3.7-6.4) after a single operation with LN to 16.1 (95% CI: 6.9 -31.8) after a second such operation. CONCLUSIONS. LN is a marker of i ncreased CA risk that is further exacerbated by episodes of preexistin g benign breast epithelial proliferative changes, and that remains sub stantially elevated for many years. (C) 1996 American Cancer Society.