The ability of immune system cells to fight cancer



The death toll from cancer, which currently stands at 8.2 million each year, is expected to rise with an aging population. [1] There are two broad types of carcinomas: metastatic, which usually results in cancer-related death, and nonmetastatic. Metastasis was once considered a phenomenon in the later stages of disease progression, but in recent years, metastatic dissemination has been observed during the early stages of cancer development. [1] Cancer cells that have metastasized will adapt cellular traits to allow them to invade distant organs following their getaway from primary tumors. [1]


An inflammatory response linked to cancer during various stages of tumorigenesis is responsible for genomic instability, epigenetic alteration, cancer cell proliferation, enhancement of anti-apoptotic pathways, and angiogenesis, eventually leading to the development of tumor spread. [1] In recent decades, inflammatory immune cells have been found to be an indispensable part in cancer-related inflammation. [1] Therefore, there has been a redirected focus in understanding how immune cells “impact tumor fate through different stages of disease: early tumor transformation, clinically detected tumors, metastatic dissemination, and therapeutic intervention.” [1]


Over 150 years ago, Rudolph Virchow was the first to focus on the link between the immune system and cancer. [2] It is the immune system's ability to ward off pathogens or infected/malignant cells that accounts for the relationship between cancer and immunity: “it detects "nonself" antigens from pathogens or infected/malignant cells; it encompasses effector functions that specifically target and destroy the pathogen or infected/malignant cells while protecting the host; and it develops immunological memory via the adaptive immune responses for subsequent defense mechanisms following an injury or an attack against the host.” [2] In the immune system’s defense, it has obtained the features for immunoediting, which “provides a balance between immune surveillance and cancer progression in the realm of oncology.” [2]


The defense system of biochemical processes that protect the body against “nonself” proteins consist of the immune system’s “soluble bioactive molecules, cytokines, proteins, and cells.” [2] An immune system's innate and adaptive responses are responsible for protecting the host and maintaining homeostasis. [2] These immune responses are considered innate because they are fast-acting and nonspecific, such as their response against “pathogenic microbes, allerg