THE IMMUNE SYSTEM NORMALLY DESTROYS CANCER BEFORE IT BECOMES A TUMOR
Immunotherapy in cancer treatment is based on the concept of utilizing the bodies innate immunity to destroy cancer (by stimulating the immune function somehow) and is appealing from a basic level. Other terms to describe this are Immuno-Oncology and Radio-Immunotherapy. Instinctively we know that we already have a process or system in our body that recognizes cancer cells and destroys them. We humans are able to flourish in a pretty hostile environment, with chemical, environmental, biological toxicity everywhere. The reason we flourish is in large part due to our immune system. The sources and effects of environmental toxicity are discussed elsewhere, this discussion is limited to the immune recognition of malignancy. Mutations in the cells are a constant phenomenon and I would estimate that there are hundreds of potential cancer causing events that occur daily. The body has tremendous protective mechanisms which recognize the abnormality and repair it almost immediately. The speed of molecular events in the oxidation and reduction cycle are measured in millionths of a second. Repair enzymes (p53, recA, etc.) are constantly examining the DNA and correcting any abnormality discovered. Thus, 99.999% of all abnormalities are identified and repaired very quickly. Unfortunately, 1 mutation in 10,000 does escape the body’s defenses. These are the mutations that may lead to cancer. To learn more about various ways that the body will recognize and repair DNA damage, please review the section on mutation and cancer. Once a mutation has established itself in the cell and began to grow, the body’s immune system is often alerted to the presence of abnormal tissue and will respond and destroy the abnormal cells. Thus, 99.9% of the mutations are eradicated by the immune system. But no system is perfect, and occasionally a cancer cell learns to avoid detection by the immune system – this is how the cancers are formed. We then recognize them as lung or breast or colon etc cancer.
The immune system is a sophisticated collection of tissues that includes the blood, lymphatic system, thymus, spleen, skin, and mucosa.
There are two main types of blood cells that compose the Adaptive immune system, the T cells which are matured in the Thymus and the B cells which are derived from the bone marrow but mature in the Peyers patches of the intestine. The B cells are responsible for production of antibodies (proteins which recognize a foreign substance like a virus or bacteria), and the T cells recognize abnormal changes to the cells and direct the immune response. The Natural Killer (NK) cell is part of the Innate Immunity and is the primary way that the body recognizes and kills cancers, using something called the Major Histocompatibility Antigens.
One of the main challenges in designing effective immune treatments against cancer is that the cancers which have developed have developed the ability to avoid alerting the immune response. Due to a variety of reasons, the body’s immune cells do not recognize that the cancer is abnormal and do not attack the cancer. Thus, merely enhancing immunity does not reliably destroy cancer. Cancer has many ways that it escapes immune recognition, including secreting substances which suppress the T and NK cells, or selectively growing the portions of the cancer that do not express abnormal proteins on the surface, thereby never alerting the bodies immune system at all.
ent of lung cancer. The results demonstrated that the patients who received radiation therapy along with the immune stimulator had double the progression free time as well as double the survival (11.6 months vs. 5.3 months), when compared to patients only receiving the immune stimulator. It would appear that the radiation therapy caused cancer cell death which released many of the abnormal cancer proteins into the extracellular environment, allowing the cell mediated immunity ( T cells and Natural Killer cells) to recognize the cancer and mount a reaction to the remaining tumor in the body. Thus, radiation overcame the cancer cells ability to avoid immune recognition. This is yet another study that has demonstrated a significant advantage to immunotherapy in cancer treatment. The side effects appeared quite modest, which is another advantage over more traditional techniques of treatment.