# Immunohistochemical Expression of Laminin 332 in Triple-Negative Breast Carcinoma: A Cross-Sectional Study

## TL;DR

This study examines how laminin 332 is expressed in triple-negative breast cancer and its link to cancer features like lymphovascular invasion.

## Contribution

The study identifies a statistically significant association between laminin 332 expression and lymphovascular invasion in triple-negative breast cancer.

## Key findings

- All 50 TNBC cases showed positivity for laminin 332 immunohistochemical expression.
- Laminin 332 IHC scores were significantly associated with lymphovascular invasion presence or absence.
- Higher-grade tumors and lymphovascular invasion were common in the studied TNBC cases.

## Abstract

Background: Breast carcinoma (BC) is the most common malignancy among women and is the leading cause of mortality among females. Triple-negative breast carcinoma (TNBC) is a diverse disease based on immunohistochemistry (IHC) and is estrogen receptor (ER) negative, progesterone receptor (PR) negative, and human epidermal growth factor (HER2) negative. TNBC has a distinct molecular profile, is more aggressive, lacks targeted therapies, and has a worse prognosis than other types of breast cancer. Laminin is a glycoprotein that plays several roles in cancer progression, including cell proliferation, invasion, metastasis, and epithelial-mesenchymal transition.

Aim and objectives: This study aimed to evaluate the immunohistochemical expression of laminin 332 in TNBCs and to study the association of laminin 332 expression with clinicopathological parameters of TNBCs.

Materials and methods: All the cases of TNBC received from the Department of Surgery at RL Jalappa Hospital and Research Institute to the Department of Pathology attached to Sri Devaraj Urs Medical College, Tamaka, Karnataka, from January 2019 to September 2024 were considered for the study. Both prospective and retrospective cases were considered. The data and paraffin blocks were retrieved from the archives of the Department of Pathology. Histopathological parameters of TNBC cases were studied, and laminin 332 IHC was performed. The association of IHC expression of laminin 332 and histopathological parameters was evaluated.

Results: Among 50 TNBC cases, 26 (56%) were elderly patients above 50 years of age. A higher proportion of cases, i.e., 23 (46%), were grade 3 tumors; 46 (92%) cases had infiltrating ductal carcinomas (IDC); 39 (78%) had lymphovascular invasion (LVI); 46 (92%) were without perineural invasion (PNI); and 22 (44%) had high-grade tumor-infiltrating lymphocytes (TILS). All the TNBC cases exhibited positivity for either a laminin 332 IHC score of 5 (64%) or a laminin 332 IHC score of 6 (36%). Laminin 332 IHC score of 5 (71.8%) was associated with the presence of LVI, and laminin IHC scores of 6 (p-value 0.041) and 7 (63.6%) were associated with the absence of LVI, which has a statistically significant association with p-value 0.041.

Conclusions: All the TNBC patients were positive for laminin 322, but there was a statistically significant association only with lymphovascular invasion. TNBC, hence, exhibits aggressive behavior and is associated with unfavorable clinicopathological outcomes.