1. In a prospective cohort study of over 1000 patients with lobular carcinoma-in-situ, the use of a chemopreventative agent was associated with a significantly reduced risk of invasive breast cancer.
2. Age of diagnosis and family history were not found to predict risk for breast cancer in this cohort.
Evidence Rating Level: 2 (Good)
Study Rundown: Lobular carcinoma-in-situ (LCIS) is a rare, non-invasive feature found on breast biopsy that has been associated with an increased risk for invasive breast cancer. The current management option for this diagnosis may range from observation with or without chemoprevention (aromatase inhibitor or selective estrogen receptor modulators) to bilateral prophylactic mastectomies. The purpose of this large prospective cohort study was to examine the long-term outcomes for patients with LCIS as well as to identify clinicopathologic risk factors for invasive breast cancer in this cohort.
The study prospectively followed over 1000 patients diagnosed with LCIS that were managed with either surveillance (with or without chemoprevention) or bilateral prophylactic surgery. At the conclusion of the trial, the annual incidence of breast cancer in this population was found to be 2% per year, with a cumulative 15-year risk similar to previous reported studies. Furthermore, the use of chemoprevention was associated with a significant reduced risk of cancer. Interestingly, age of diagnosis and family history of breast cancer did not demonstrate significant association for invasive breast cancer. The results of this study support the use of chemopreventative agents in the management of patients with LCIS. This is the largest prospective cohort to analyze the long-term prognosis of patients with LCIS. However, the study is limited by the observational design, which could not account of all confounding variables. Nevertheless, these findings may assist with the counseling as well as short- and long-term management of patients with newly diagnosed LCIS.
In-Depth [prospective cohort]: This was a large, single center, prospective cohort study of women diagnosed with lobular carcinoma in-situ (LCIS) between 1980 and 2009. A total of 1060 patients were included. All patients underwent surgical excision at the time of LCIS to rule out synchronous malignancy. 78% of patients underwent surveillance only, 17% of patients underwent surveillance with chemoprevention and 5% of patients underwent bilateral prophylactic mastectomy. After a mean follow-up of 81 months, the annual cancer development rate in this cohort was found to be at 2% per year with a cumulative incidence of 26% at 15 years. Age of LCIS diagnosis, menopausal status, family history, bilateral LCIS, BIRADS breast density, and need for subsequent biopsies were not associated with subsequent cancer diagnosis. The use of chemoprevention was associated with decrease in the incidence of invasive breast cancer (HR: 0.27; 95% CI: 0.15-0.5; p < 0.001).
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