What is T lymphocyte (T-cell) rich breast carcinoma?

From the Guidelines

T lymphocyte rich breast carcinoma is a rare subtype of invasive breast cancer characterized by a dense infiltration of T lymphocytes surrounding a relatively small number of malignant breast cancer cells, and its management should prioritize a multidisciplinary approach with consideration of immunotherapy due to its robust immune response, as suggested by recent guidelines 1.

Key Characteristics

• This cancer typically presents as a tumor where less than 10% of the cells are actual cancer cells, while the majority consists of T lymphocytes and other inflammatory cells.
• The diagnosis requires careful pathological examination with specialized immunohistochemical staining to distinguish the cancer cells from the surrounding immune infiltrate.
• T lymphocyte rich breast carcinoma generally has a better prognosis than other invasive breast cancers due to the robust immune response against the tumor.

Treatment Approach

• Treatment follows standard breast cancer protocols including surgery, possibly followed by radiation, chemotherapy, hormonal therapy, or targeted therapy depending on the tumor's specific characteristics such as hormone receptor status and HER2 expression.
• The strong immune component of this cancer subtype has generated interest in potential immunotherapy approaches, as outlined in recent clinical practice guidelines for early breast cancer 1.
• Patients with triple-negative breast cancer (TNBC) may benefit from chemotherapy with or without an immune checkpoint inhibitor (ICI) such as pembrolizumab, as recommended by the ESMO clinical practice guideline for diagnosis, treatment, and follow-up of early breast cancer 1.

Management Considerations

• Patients should be managed by a multidisciplinary team with experience in breast cancer to ensure optimal outcomes.
• The use of dose-dense schedules of chemotherapy, with granulocyte colony-stimulating factor support, should be considered given their documented benefit over non-dose-dense schedules, as suggested by the ESMO guideline 1.
• For patients with residual disease after neoadjuvant therapy, adjuvant capecitabine for 6-8 cycles may be offered, as recommended by the ESMO guideline 1.

From the Research

Definition and Characteristics

• T lymphocyte rich breast carcinoma is a type of breast cancer characterized by a high infiltration of tumor-infiltrating lymphocytes (TILs) [ 2 ].
• It is also known as TILs-rich invasive breast carcinoma no special type (IBC-NST) and is included in the fifth edition WHO classification of breast tumors [ 2 ].
• Typical medullary breast carcinoma (MBC) represents one end of the spectrum of TILs-rich IBC-NST [ 2 ].

Immune Cell Subtypes and Prognosis

• The composition and function of TILs, including CD4, CD8, and FoxP3, can affect the prognosis of TILs-rich IBC-NST [ 2 ].
• MBC cases have been shown to have a higher CD8/FoxP3 ratio and lower numbers of lymphocytes expressing FoxP3, which may contribute to their less aggressive features and better prognosis [ 2 ].
• Regulatory T lymphocyte (Treg) infiltration has been identified as an independent prognostic factor for breast cancer-specific survival and post-recurrence survival [ 3 ].

Clinical Implications

• The evaluation of TILs and specific populations of TILs may guide prognosis and the appropriate sequencing of therapies in breast cancer [ 4 ].
• TILs-rich IBC-NST may benefit from immune checkpoint inhibitor therapy, and further investigation is needed to determine the optimal treatment strategies [ 4 ].
• The immune landscape of metastatic breast cancer, including TILs and Treg infiltration, can change with tumor progression and may have implications for prognosis and treatment [ 3 ].