With our ongoing series on immunotherapy and comparisons between various cancer treatment techniques, it is important to see what it is that different therapies do to the human body. In the field of cancer research, there are many types of treatment that are currently used. Today, we examine what radiation therapy and several variations of targeted therapy and immunotherapy do, in order to discuss the effects of cancer treatment on the body:
In radiation therapy, cancer cells are targeted and destroyed by using external beam radiation, systemic radiation therapy, or brachytherapy. The goal of each method is to control cancer cell growth, while eliminating existing tumors. Methods can vary widely in this discipline, as some use wider application areas that blanket areas of the body with radiation, while other’s use a more targeted approach that minimizes treating (and damaging or killing) healthy cells.
Beam-based radiation therapies bombard areas of the body with radiation within a controlled environment. This means that the radiation is applied externally and not stored inside of the body. Systemic radiation uses what are considered to be unsealed sources of radiation that are generally injected in liquid form. This can require a short hospital stay, as the systemic radiation can leech from the body and can be hazardous to others. Similarly, the radioactive implants used in brachytherapy – some temporary that are removed, some that are smaller and lose their potency over time – also store radiation in the body. Each type can require some manner of quarantine, in case radiation escapes.
The effects of cancer treatment using radiation can vary, depending on dosage, delivery method and the organs targeted. Skin irritation and lack of energy are quite often experienced. Skin and other treatment surfaces can be damaged – in cases of exterior treatment – along with some localized sores, especially in cases where treatment was in the mouth, throat or other soft tissues. While it is possible for radiation to cause other cancers to form, chances of this are now much less likely then they use to be. For information on effects of cancer treatment using radiation on specific organs, please consult the American Cancer Society site.
Targeted therapies concentrate on disrupting the growth of cancer cells, through blocking or otherwise interfering with the formation of blood vessels (angiogenesis inhibitors) and cell signalling (enzyme inhibitors). Some targeted drugs can also cause apoptosis – cell death – in cancer cells. These therapy types are designed to effect cancer cells directly.
Angiogenesis inhibitors upset blood vessel development, in order to deplete oxygen and other nutrients from cells. When first discovered, this method was thought to be a possible miracle cure. While still in circulation, this specific targeted therapy approach is used predominantly with a regiment of other options, due to several limitations, aside from lenalidomide and thalidomide used for treatment of myeloma. The field of enzyme inhibition in cancer treatments is quite large, with many companies and drugs concentrating on specific enzymes and proteins. Some of these include signal-transduction, proteasome, artomatose, glycolytic and other inhibitors. In each case, the therapies work to block cell growth, division, and intercellular communication in different manners. They are also commonly used in combination therapies, in order to slow the spread of cancer, along with chemotherapy or immunotherapy.
Effects of cancer treatment under the targeted therapies approach may not have the same damaging impact that many chemotherapy drugs have but can still have many side effects. With the wide array of treatment options available within targeted therapies, side effect can vary greatly. Due to the way in which these drugs interact with cell signalling and proteins, there is the possibility that they will also affect some health cells. Average side effects of cancer treatment in the targeted therapies branch include rashes and other skin problems, damage to hair, burning of the eyes and stomach problems. Exterior irritants can play a major role in the severity of these side effects.
Immunotherapy is the discipline that stimulates, reinforces or otherwise bolsters the human immune system against cancer. While the other methods mentioned attack cancer cells more directly, immunotherapy improves the immune system and helps it locate and destroy cancer cells itself. Because of this, immunotherapy is often viewed as a less invasive and less personally damaging approach.
Generally, cancer immunotherapy is broken into three categories: monoclonal antibodies, vaccines and non-specific immunotherapies. Monoclonal antibodies are lab-made versions of specific proteins found within the immune system that can trigger the body to attack cancer cells, move radiation or other therapy agents into cancer cells, disrupt cancer cell signals and division, along with other possible outcomes. Cancer vaccines (the most rare type) can be either preventative – attempting to lower cancer risk – or they can be used as treatment, in order to boost the immune system. Finally, the non-specific immunotherapies are a bit more ambiguous and tend not to target one specific cell type.
Cytokines can be used to boost immune functionality or to help repopulate white or red blood cells, along with providing an option for combination therapy. Interleukins – the use of which OncoSec concentrates on – are a specialized group of cytokines that control chemical signals between immune cells. This allows our potential treatment currently in clinical trials to use a plasmid DNA construct to instruct cells to produce IL-12 proteins that aid in increasing levels of T-cells and other cancer fighting agents.
Like targeted therapies, the side effects of cancer treatment using immunotherapy vary based on the specific type. Common side effects can include swelling, fatigue and flu-like symptoms. Compared to the other disciplines, immunotherapy is often thought of as having fewer and more manageable side effects.
(Main image by Giulia Ciappa)