Tumors are complex ecosystems composed of mixed populations of cells residing within dynamic microenvironmental niches. The immune system interacts intimately with tumors throughout the entire process of disease development and metastasis. This crosstalk between immune cells and cancer cells can inhibit and enhance tumor growth and is now gradually classified as the hallmark of cancer. Although many articles have been published on how tumors evade the attack of the immune system, there are still many unknown pieces of information awaiting exploration, and for researchers and clinicians, it remains a formidable task to discover effective cancer therapies based on the results of mechanistic exploration.

In this special issue, we welcome studies and reviews covering the following topics:

1. Tumorigenesis and immune responses
2. Tumor progression and immunity
3. Signal pathways that tumors exploit to avoid immune responses
4. Epigenetic mechanism of anti-tumor immune response
5. Tumor heterogeneity and immune responses
6. Immune system and cancer metastasis
7. Cancer drug resistance and immune response
8. Strategies development for cancer immunotherapy