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6 slides generated from the cancer page, with a quiz from the open benchmark and speaker notes that cite the sources. Arrow keys move between slides; Print gives one slide per page.
Invasive lobular carcinoma is the second most common type of breast cancer, about one in seven cases. Its cells have lost the glue protein E-cadherin, so they spread in single files rather than forming a lump, which makes it hard to see on mammograms and to measure. Almost all cases are hormone-receptor positive and are treated like other hormone-driven breast cancer.
Invasive lobular carcinoma is defined in the WHO classification by its discohesive growth, single cells and single-file cords infiltrating the stroma, and by loss of E-cadherin from inactivation of CDH1 (Tan 2020). The Cancer Genome Atlas profiled 817 breast tumours including 127 lobular, 490 ductal and 88 mixed: beyond E-cadherin loss, mutations of PTEN, TBX3 and FOXA1 were enriched in lobular disease, PTEN loss went with the highest AKT phosphorylation of any breast cancer subtype, proliferation and immune signatures defined three lobular transcriptional subtypes with different survival, and mixed ductal-lobular tumours were molecularly either lobular-like or ductal-like rather than true hybrids (Ciriello 2015).
How it differs from its parent: detection and surgery. Its diffuse growth makes it multicentric, multifocal and bilateral more often, with a high likelihood of incomplete excision after breast-conserving surgery; MRI and contrast-enhanced mammography surpass conventional imaging for its extent and improve surgical outcomes when added to the work-up (Healthcare 2023). Even mastectomy left positive margins in 10.6 percent of 357 patients, and in 18.7 percent of T3 tumours (American Journal of Surgery 2022). Metastases favour the peritoneum, ovaries, gut and meninges, and are often small foci needing immunohistochemistry to find in nodes; in 1,269 SEER patients meeting the Z0011 criteria, sentinel node dissection alone and full axillary dissection gave the same survival (PLoS One 2014). It is extremely uncommon in men (Breast Cancer 2017).
| Setting | Approach | Guideline |
|---|---|---|
| All stages | Treated as HR-positive breast cancer: surgery planned with MRI, endocrine therapy, CDK4/6 inhibitors in advanced disease; sentinel node biopsy as in ductal disease. | not mapped |