Surgery for Classic, Pleomorphic and Non-classic Lobular Carcinoma In Situ: Surgery Rate, Risk of Upstaging and Short-Term Follow-Up.

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.

Estrogen-Receptor Loss and Mutation in Estrogen-Receptor-Positive Metastatic Breast Cancer and the Effect on Overall Survival.

In patients with metastatic estrogen-receptor (ER)-positive HER2-negative breast cancer, the loss of ER expression and the mutation of -the gene encoding the ER receptor-are mechanisms for resistance to endocrine therapy. We aimed to determine the frequency of these mechanisms and their interaction. Metastases were retrieved from our pathology files.

Validation and Clinical Utility of a Prediction Model for the Risk of Upstaging to Invasive Breast Cancer After a Biopsy Diagnosis Ductal Carcinoma In Situ.

Background: This study aimed to validate the DCIS-upstage model, a previously developed model to predict the risk of upstaging to invasive breast cancer in patients with biopsy-proven ductal carcinoma in situ (DCIS) in a more recent cohort and to assess the model's clinical utility.

Methods: The model was validated in a registry cohort (n = 2269) and in an institution cohort (n = 302). A calibration plot was made, followed by a decision curve analysis (DCA).