Population-Based Analysis of Breast Cancer Incidence and Survival Outcomes in Women Diagnosed with Lobular Carcinoma In Situ

A diagnosis of lobular carcinoma in situ (LCIS) is associated with an increased risk of developing breast cancer, although little data exist on long-term patient outcomes, including those who develop subsequent breast malignancies.

The Surveillance, Epidemiology, and End Results (SEER) database was used to identify women with a histological diagnosis of LCIS between 1983 and 2014. The incidence and clinicopathologic features of subsequent malignancies were then examined, and the Kaplan–Meier method and multivariable Cox PH regression used to obtain breast cancer-specific survival (BCSS) estimates and associated hazard ratios.

Overall, 19,462 women swith a mean age at LCIS diagnosis of 53.7 years, and a 10- and 20-year cumulative incidence of subsequent breast malignancy of 11.3% [95% confidence interval (CI) 10.7–11.9%] and 19.8% (95% CI 18.8–20.9) met the eligibility criteria. At a median follow-up of 8.1 years (range 0–30.9) a total of 1837 primary breast cancers were diagnosed, of which 55.2% were diagnosed in the ipsilateral breast. Most breast cancers were of low/intermediate grade, hormone receptor-positive, and diagnosed in early stages. Of subsequent malignancies, invasive ductal carcinoma (IDC) distributed equally across both breasts, whereas invasive lobular carcinoma (ILC) was more likely to present in the ipsilateral breast (69.0% ILC vs. 49.2% IDC; p < 0.001). On multivariable analysis, type of surgical treatment for LCIS had no affect on long-term survival (p = 0.44). The 10- and 20-year BCSS for women with LCIS was 98.9 and 96.3%, respectively.

Women with LCIS who are diagnosed with a subsequent primary breast cancer are often diagnosed in early stages and have excellent BCSS.