How should phenotyping (immunohistochemistry, fluorescence in situ hybridization, next‑generation sequencing) be performed in a newly diagnosed solid tumor, and how do markers such as HER2 (human epidermal growth factor receptor 2), estrogen and progesterone receptors, PD‑L1 (programmed death‑ligand 1), MSI (microsatellite instability)/MMR (mismatch repair) proteins, and TMB (tumor mutational burden) guide treatment decisions?

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Last updated: February 9, 2026 • View editorial policy

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