The NAPOLI Study is a retrospective multicenter observational study designed to characterize hormone receptor-negative/low invasive lobular carcinoma of the breast. The study will collect real-world clinicopathological, molecular, therapeutic and outcome data from patients diagnosed and treated at participating centers. The aim is to describe the clinical behavior, pathological features, receptor profile, treatments received and oncologic outcomes of this rare breast cancer subtype.
Female or male patients aged ≥18 years;
Histologically confirmed ILC, confirmed by E-cadherin loss/aberrant expression and/or p120 cytoplasmic relocalization and/or CDH1 alteration;
HR-negative (ER <1% and PR <1%) or HR-low (ER and/or PR 1-10%) disease, as defined by ASCO/CAP guidelines, is eligible regardless of HER2 status (assessed according to 2025 ASCO/CAP criteria, with HER2-low and HER2-ultralow status recorded where assessable);
HR-positive (ER>10% according to the ASCO/CAP guidelines) ILC is eligible only if HER2 status is positive;
Pure IC NST without any lobular invasive component;
ER or PR expression >10% in the invasive component, in cases with negative HER2 status;
In situ lobular neoplasia (lobular carcinoma in situ) without an invasive component;
De novo stage IV disease (such patients, if they underwent surgery of the primary tumor, will be captured in a separate exploratory cohort for a dedicated analysis)