# Invasive lobular carcinoma of the breast

Source: https://onco.cc/cancers/invasive-lobular-carcinoma/  
OnCo record `invasive-lobular-carcinoma` (Cancer). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

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.

## Summary

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).

How common: about 15 percent of breast cancers (Cancer Research UK).

Treatment follows the HR-positive breast cancer page, because almost all lobular cancers are hormone-receptor positive and HER2-negative: endocrine therapy with CDK4/6 inhibitors in advanced disease, and surgery with the imaging above. Whether lobular disease responds differently to chemotherapy or specific endocrine agents is under study; the fluoroestradiol PET trial linked here images its oestrogen receptors.

## Fields

- Kind: Cancer
- Last checked: 2026-09-24
- Also known as: Invasive lobular carcinoma; ILC; Lobular breast cancer; Invasive lobular breast cancer; Infiltrating lobular carcinoma; Pleomorphic lobular carcinoma
- Tags: subtype-page; wave4; breast
- Group: breast
- Burden: Around 15 in every 100 breast cancers, the second most common type (Cancer Research UK). GLOBOCAN counts it within the 2,296,840 breast cancers of 2022.
- Subtypes: Classic invasive lobular carcinoma (single-file, E-cadherin negative, luminal A); Pleomorphic lobular carcinoma (higher grade, sometimes HER2-positive); Solid, alveolar and tubulolobular variants; Mixed ductal and lobular carcinoma (molecularly one or the other); Lobular carcinoma in situ (own page)
- Biomarkers: E-cadherin loss on immunohistochemistry and CDH1 inactivation; Oestrogen and progesterone receptor (almost always positive), HER2 (usually negative); PTEN, TBX3 and FOXA1 mutations (enriched); Extent on MRI or contrast-enhanced mammography before surgery

## Sections of this record

The page is a hub with ten sections in reading order; large sections have their own page. The same plan as JSON: https://onco.cc/api/v1/cancers/invasive-lobular-carcinoma/sections.json

- Overview (on the hub): The TL;DR, the family this cancer belongs to, the organ, who gets it and what the state of the art is. https://onco.cc/cancers/invasive-lobular-carcinoma/#overview
- What it is (on the hub): Anatomy, the subtypes and how they differ, how it is staged, and where advanced disease spreads. https://onco.cc/cancers/invasive-lobular-carcinoma/#what-it-is [5 subtypes]
- Finding it (on the hub): How it shows itself, how it is confirmed, what screening exists, and the biomarkers clinicians test for. https://onco.cc/cancers/invasive-lobular-carcinoma/#finding-it [4 biomarkers]
- Treating it (on the hub): The standard of care by setting, the medicines, surgery and radiotherapy named in it, and the regimens behind them. https://onco.cc/cancers/invasive-lobular-carcinoma/#treating-it [1 setting, 1 decision with options]
- Evidence (on the hub): Trials recruiting now, the landmark trials, the key papers and what they mean, the latest literature, and the milestones year by year. https://onco.cc/cancers/invasive-lobular-carcinoma/#evidence [1 trial]
- The science (on the hub): The molecular landscape: the targets and how often each appears, the pathways, the mechanics stages and the preclinical models. https://onco.cc/cancers/invasive-lobular-carcinoma/#science [3 targets]
- Where you are (own page): Cases by country, the UK and NHS pathway and other country lenses, and the expert centres with trials on record. https://onco.cc/cancers/invasive-lobular-carcinoma/where-you-are/
- Living with it (on the hub): The decisions you may face, the aids that walk through them, the warnings on record, the first sixty days and the questions to ask. https://onco.cc/cancers/invasive-lobular-carcinoma/#living-with-it [8 questions, 3 red cards]
- What is coming (own page): Everything in development, the open problems and what is being done about them, the roadmaps, and what changed on this record. https://onco.cc/cancers/invasive-lobular-carcinoma/coming/ [6 medicines]
- Data (own page): Every connected record, the notes, the JSON, Markdown and RDF twins, and where the record came from and when it was checked. https://onco.cc/cancers/invasive-lobular-carcinoma/data/ [18 connected records]

## Standard of care

- 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. ([HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [Endocrine therapy (SERMs, AIs, SERDs)](https://onco.cc/technologies/endocrine-therapy/), [CDK4/6 inhibitors](https://onco.cc/technologies/cdk46-inhibitor/), [Tamoxifen](https://onco.cc/drugs/tamoxifen/), [Letrozole (and other aromatase inhibitors)](https://onco.cc/drugs/letrozole/), [Mastectomy](https://onco.cc/terms/mastectomy/))

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Invasive_lobular_carcinoma
- Cancer Research UK: invasive lobular breast cancer: https://www.cancerresearchuk.org/about-cancer/breast-cancer/types/invasive-lobular-breast-cancer
- Tan 2020, Histopathology: the 2019 WHO classification of tumours of the breast: https://doi.org/10.1111/his.14091
- Ciriello 2015, Cell: comprehensive molecular portraits of invasive lobular breast cancer (TCGA): https://doi.org/10.1016/j.cell.2015.09.033
- Healthcare 2023: invasive lobular carcinoma, a review of imaging modalities and pathology concordance: https://doi.org/10.3390/healthcare11050746
- American Journal of Surgery 2022: positive margins after mastectomy in 357 patients with invasive lobular carcinoma: https://doi.org/10.1016/j.amjsurg.2021.05.021
- PLoS One 2014: sentinel node dissection alone versus axillary dissection in early invasive lobular carcinoma, SEER: https://doi.org/10.1371/journal.pone.0089778
- Breast Cancer (Dove) 2017: invasive lobular carcinoma of the male breast, systematic review: https://doi.org/10.2147/bctt.s126341

## Connected records

- cancers: [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/), [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [Invasive breast carcinoma of no special type (invasive ductal carcinoma)](https://onco.cc/cancers/invasive-breast-carcinoma-no-special-type/), [Lobular carcinoma in situ (LCIS)](https://onco.cc/cancers/lobular-carcinoma-in-situ/), [Neuroendocrine neoplasms of the breast](https://onco.cc/cancers/neuroendocrine-neoplasms-breast/), [Tubular carcinoma of the breast](https://onco.cc/cancers/tubular-carcinoma-breast/)
- technologies: [CDK4/6 inhibitors](https://onco.cc/technologies/cdk46-inhibitor/), [Endocrine therapy (SERMs, AIs, SERDs)](https://onco.cc/technologies/endocrine-therapy/)
- targets: [CDH1](https://onco.cc/targets/cdh1/)
- drugs: [Abemaciclib](https://onco.cc/drugs/abemaciclib/), [Fulvestrant](https://onco.cc/drugs/fulvestrant/), [Letrozole (and other aromatase inhibitors)](https://onco.cc/drugs/letrozole/), [Palbociclib](https://onco.cc/drugs/palbociclib/), [Ribociclib](https://onco.cc/drugs/ribociclib/), [Tamoxifen](https://onco.cc/drugs/tamoxifen/)
- terms: [Mastectomy](https://onco.cc/terms/mastectomy/)
- trials: [[18F]Fluoroestradiol-PET/CT Imaging of Invasive Lobular Carcinoma](https://onco.cc/trials/nct04252859/)

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JSON: https://onco.cc/api/v1/entities/invasive-lobular-carcinoma.json