Clinical and histological characteristics of peritoneal metastases from invasive lobular breast cancer

Background:

In 40% of patients with metastasized Invasive lobular breast cancer (ILC) peritoneal metastases have been identified. Mechanisms or clinical and patho-histological parameters regarding an increased risk of metastasis have not yet been identified for ILC. Additionally, there is a special need to differentiate and identify those patients with a higher risk for the development of metastases.

Methods:

In this study we evaluated the clinical and pathologic features of patients treated at Charité Universitätsmedizin for invasive lobular breast cancers and their metastases. For this we have retrospectively identified all lobular breast cancers in our pathological database from 2007 until 2017 and combined them with clinical and patho-histological parameters and follow-up data. Since 2018 we are prospectively including ILC patients in this database.

Results:

Currently we have identified 649 (79.9%) ILC patients without metastases and 163 (20.1%) with metastases (all sites). In a subcohort of peritoneal metastases we found (while statitiscally not significant (p = 0.805) a rise in metastatic tissues while PR expression remained mostly stable with a rise in the metastatic site in only 26.7% (p = 0.715). Updated results for all metastatic subgroups will be shown on the poster.

Conclusions:

These and additional preliminary clinical data show significant differences between primary ILC with and without metastases and may have a prognostic effect. On a molecular level, we are planing to characterize primary tumors and their metastases via panel NGS and to combine the sequencing data with the clinical above data.