Background: The Dutch breast cancer guideline recommends surveillance for classic lobular carcinoma in situ (LCIS), unless there is a discrepancy with mammographic findings, and surgery for pleomorphic and non-classic LCIS.
Objective: The aim of this study was to assess adherence to the guideline in daily practice, as well as the surgery rate, risk of upstaging, and events during follow-up.
Methods: Selection of patients from a nationwide cohort diagnosed between 2011 and 2020.