J.Jpn. Surg. Soc.. 127(3): 265-273, 2026

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Feature topic

DRUG RESISTANCE AND TREATMENT STRATEGIES THROUGH TUMOR IMMUNITY IN BREAST CANCER

The treatment of breast cancer has traditionally been selected by molecular pathological subtype classification. However, significant variability in treatment response and recurrence risk exists even within the same subtype, necessitating more precise stratification. Recently, it has been revealed that the tumor immune microenvironment, including tumor-infiltrating lymphocytes and PD-L1 expression, influences clinical treatment response and prognosis. Furthermore, genetic mutations primarily known in breast cancer, such as BRCA1/2, ESR1, and PIK3CA, are also recognized as important factors defining tumor immunity. An approach that targets not only tumor cells but also the tumor immune microenvironment is necessary to overcome breast cancer progression, metastasis, and treatment resistance. Treatment selection and optimization based on stratification integrating molecular pathology, tumor immunity, and genetic mutations will be key to future breast cancer therapy.

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