This book focuses on the crosstalk between tumor cells and stromal cells, immune cells and even extracellular matrix in the tumor microenvironment with the mainly aim to reveal the motivation of cancer cell malignancy, which may provide some guiding ideas for anti-tumor therapy. The tumor immune microenvironment (TIME), a complex structure containing various immune cells surrounding tumor cells, plays a crucial role in tumorigenesis and represents a key area for activated immunotherapy, while conditions like anaplastic thyroid carcinoma (ATC) and hepatocellular carcinoma (HCC)-both aggressive cancers with poor prognoses and limited late-stage treatments-highlight the challenges posed by factors such as bile acids, which may act as potential carcinogens despite their role in lipid digestion and absorption.