Key clinical point: The overall incidence of synchronous bilateral breast cancer (BBC) and metachronous BBC (MBBC) in patients with a history of lobular carcinoma in situ (LCIS) was 2%, with the risk for MBBC being even lower in women with hormone receptor-positive BC and those receiving endocrine therapy (ET).
Major finding: The estimated 5-year risk of developing MBBC was 6.4% (95% CI 1.9%-10.7%) among women with a remaining contralateral breast at risk, with the risk being lower among those with estrogen (hazard ratio [HR] 0.13; P = .015) or progesterone (HR 0.24; P = .047) receptor-positive BC and those who received ET (HR 0.17; P = .005).
Study details: This study included 1651 women with a history of LCIS, of which 249 women developed unilateral or bilateral BC during a median follow-up of 7 years.
Disclosures: This study was partly supported by the US National Institutes of Health/National Cancer Institute Cancer Center. TA King declared receiving speakers' honoraria and serving on advisory boards for several sources. The other authors declared no conflicts of interest.
Source: Mallory MA et al. Synchronous and metachronous bilateral breast cancer among women with a history of lobular carcinoma in situ. Breast Cancer Res Treat. 2022 (Apr 29). Doi: 10.1007/s10549-022-06532-4