What Is Triple-Negative Breast Cancer (TNBC)?

This post was written with Consensus AI Academic Search Engine – please read our Disclaimer at the end of this article. Triple-Negative Breast Cancer (TNBC) is a subtype of breast cancer that is defined by the absence of three common receptors known to fuel most breast cancer growth: estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptor 2 (HER2). This lack of receptors means that TNBC does not respond to hormonal therapy or therapies that target HER2 receptors, which are effective in other types of breast cancer2 3 4.

Biological Diversity and Aggressiveness

TNBC is known for its biological diversity and aggressive nature. It tends to grow and spread more quickly than other types of breast cancer, leading to a poorer prognosis. The aggressive behavior of TNBC is partly due to its high proliferation rate and the rapid onset of resistance to chemotherapy after an initial response1 3 6. Additionally, TNBC is more likely to metastasize, particularly to the brain and lungs, compared to other breast cancer subtypes9.

Molecular and Phenotypic Similarities

TNBC shares certain phenotypic and molecular similarities with germline BRCA (gBRCA) mutated breast cancers. Approximately 10% to 20% of TNBC patients have gBRCA mutations, which are associated with homologous recombination deficiency. This deficiency makes these tumors particularly sensitive to certain types of chemotherapy and PARP inhibitors3 7.

Tumor Microenvironment and Immune Response

The tumor microenvironment in TNBC is characterized by a high presence of tumor-infiltrating lymphocytes (TILs) and the expression of programmed death-ligand 1 (PD-L1). These features make TNBC a suitable candidate for immunotherapy. The presence of TILs and PD-L1 suggests an ongoing immune response within the tumor, which can be harnessed by therapies that block immune checkpoints, potentially leading to durable responses1 5 6.

Prognosis and Survival Rates

The prognosis for TNBC is generally poorer compared to other breast cancer subtypes. The rapid progression to metastatic stages and the high likelihood of recurrence contribute to lower overall survival rates. Studies have shown that the five-year recurrence-free survival (RFS) and overall survival (OS) rates are significantly lower for TNBC patients compared to those with other types of breast cancer4 8.

Conclusion

Triple-Negative Breast Cancer (TNBC) is a distinct and aggressive subtype of breast cancer characterized by the absence of ER, PR, and HER2 receptors. Its aggressive nature, rapid progression, and poor prognosis make it a significant area of medical need. The unique molecular and immune characteristics of TNBC offer potential avenues for targeted therapies and immunotherapies, although effective treatment options remain limited.

Disclaimer

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