Introduction
Cancer was initially thought to occur due to changes in cell and gene expression. However, it is now identified as a disease rooted in the tumor microenvironment (TME). During the past two decades, remarkable progress has been made in understanding the complex nature of the tumor microenvironment and how it influences the responses to various anticancer treatments, including immunotherapies. Immunotherapy for cancer includes leveraging the body’s immune system to find and eliminate cancer cells, resulting in favorable treatment outcomes in both blood cancers and solid tumors. Tumorigenesis, metastasis, and progression are closely linked with the tumor microenvironment, highlighting the importance of understanding the characteristics of varus cells and molecules within it, as well as the interaction between programmed death‐1 (PD‐1) and the tumor microenvironment, in the pursuit of effective cancer immunotherapy.
Over the last few decades, there have been rapid changes in tumor treatment approaches. Older methods like radiotherapy and chemotherapy have shown certain limitations. Scientists are extensively studying the tumor environment and how the immune system interacts with it. New treatments like engineered cells, immunotherapy using antibodies, and vaccines have been effective with fewer risks. The study of tumor microenvironment has been an emerging field in medical oncology and has gained interest from many physicians and researchers. The study of the tumor microenvironment presents both challenges and chances in the field of cancer research. By having a deep understanding of the tumor microenvironment and its effect on how tumors develop and progress, medical field experts can revolutionize their approach to precision medicine in cancer treatment.
What Is a Tumor Microenvironment?
The tumor microenvironment refers to the adjacent structures or surroundings of a tumor within the body, including the extracellular matrix, immune cells, blood vessels, and other cells such as fibroblasts. There has been a continuous interaction between a tumor and its microenvironment, which can either support or hinder each other's functions. The development of tumors is impacted by an abnormal immune response and changes in the body's balance. Cancer growth and metastasis are influenced by the interaction of immune cells with cancer cells in the tumor environment. The tumor microenvironment aids tumor cells' survival and helps in functioning better. The aggressiveness and spread of cancer cells to different parts of the body are enhanced by the interaction between the different cells and structures in the tumor microenvironment.
Research suggests that certain types of immune cells, both adaptive (like T and B cells) and innate (like neutrophils, macrophages, and natural killer cells), help in promoting tumor growth when they are present in the tumor microenvironment. Specifically, CD8+ T cells, the ones that are important for killing cancer cells, play a key role in preventing and eliminating tumors. However, in many patients, these cells fail to effectively clear cancer cells, leading to further disease progression, often because the CD8+ T cells become depleted. Additionally, tumor metastasis to other parts of the body also relies upon interactions within the tumor microenvironment involving various cells and factors.
How Does Tumor Microenvironment Play a Role in Cancer Progression?
Studies have shown that when the metabolism of a tumor changes, it provides adequate energy and substances for the tumor to grow, while also hindering the body's anti-tumor response. In the tumor microenvironment, there is a proper balance of metabolic needs between tumor cells and immune cells. Activation of natural killer cells (NK) and cytotoxic T-cells multiplies the need for nutrients like glucose and amino acids, which are also a need of tumor cells, too. This feud for nutrients limits the function and growth of immune cells targeted at the tumor. Furthermore, alterations in metabolite levels and the accumulation of waste products like lactic acid due to tumors create an environment that suppresses the immune system locally, promoting tumor spread and advancement.
The tumor microenvironment influences patients' response to treat tumors and their chances of survival. It is also crucial to develop therapies that counteract the immunosuppressive effects of the tumor microenvironment, enhance the function of T cells, and reduce the growth of tumor-supporting cells within it. Specifically, re-educating the immune cells in the tumor microenvironment to limit immunosuppression is relentless.
How Does Tumor Microenvironment Play a Role in Treatment Resistance?
It has been widely known that the immune system can detect cancer cells. However, cancer cells usually have issues with antigen presentation (presenting antigens) and lose their ability to be recognized by the immune system (antigenicity). This allows them to evade detection and continue to grow, ultimately making patients resistant to treatment. Tumor cells also dodge the immune system by altering the environment around them, often by bringing in immune-suppressing cells. Immuno-oncology, or immunotherapy, helps to restore and activate a patient's immune system to battle cancer. Recent treatment approaches in this area have shown great promise. For example, adoptive T-cell immunotherapy has made remarkable strides in treating various cancers.
The tumor microenvironment has a crucial role in the growth, spread, and spread of cancer cells. Recent research has made significant strides in perceiving how certain types of cells, like myeloid cells and cancer-associated fibroblasts (CAFs), within the tumor microenvironment can affect cancer development. Specifically, there is a lot of interest in studying how tumors become resistant to traditional treatments.
Conclusion
In summary, it is important to understand the relationship between the tumor microenvironment, and immunotherapy can effectively boost the immune system's ability to fight tumors by favorably shaping the tumor microenvironment. It is also important to use models that exactly represent the characteristics of the microenvironment to enhance understanding of cancer therapy. Furthermore, it would be helpful to develop treatments that target multiple signaling pathways instead of just those that sustain tumor microenvironments. By investigating tumor cells and their job in resisting therapy, physicians can make advancements in cancer treatment.
