Using Photodynamic Therapy to Treat Cancer
Photodynamic Therapy is an intriguing new method of cancer treatment that has had some promising initial results. The idea of using light to treat disease is not new. A German doctor named Friedrich Meyer-Betz used what he called photoradiation therapy on his own skin in 1913. The technique attracted new interest in the 1980s and with some modification and modernization is being touted as being a less invasive less costly and less painful way to treat cancer than chemotherapy. Read on to learn more about this novel therapy and its potential uses.
Understanding Cancer: The human body is made of millions of cells. Cells are the primary building blocks of life and are responsible for all body functions. Cancer cells are different in two ways from healthy cells. One, they divide and spread constantly. Healthy body cells go through long periods where they are not dividing. Cancer cells never rest. Two, cancer cells do not die like healthy body cells do. A normal cell has a finite life span. It wears out, dies, and is replaced by new healthy cells. This process can be visualized when our skin gets dry. Cancer cells either do not die or they live a lot longer than normal cells do. These two differences explain why tumors form, why cancer spreads and why cancer is so hard to get rid of.
How Photodynamic Therapy Works: Photodynamic Therapy (PDT) involves the use of a photosensitizing agent and a light source, usually a laser. Two to three days prior to a treatment the patient receives an injection of a photosensitizing agent. Every cell in the body absorbs the agent, making all the body cells sensitive to certain kinds of light. The key to the therapy is that the photosensitizing agent cycles out of healthy cells much more quickly than it does cancer cells.
Therefore, the cancer cells stay light (photo) sensitive for a much longer time. The treatment itself consists of exposing the tumor to light. The photosensitizer left in the cancer cells absorbs the light and produces a form of oxygen that kills the cancer cells. Preliminary research suggests that PDT also damages the blood vessels supplying the tumor, thus starving it of the nutrients that the cells need to continue multiplying.
The light source is often a laser, but other light sources can work as well. To further target a tumor light can be sent through fiber optic cables carried by and endoscope to the tumor site, such as in the lungs or on the esophagus. Even light-emitting diodes (LEDs) can be used to treat skin cancer.
PDT does have limits and a few side effects, however. PDT is only effective on tumors that can be reached by light. If a tumor is too deep in the body for light to reach it or is too big for light to penetrate through it PDT will not be effective. Also, if cancer has spread throughout the body PDT will not be able to eradicate all the cancer and a traditional chemotherapy will likely be necessary.
Side effects of PDT are much less than those of chemotherapy but they are side effects nonetheless. If any photosensitizer remains in healthy cells next to cancer cells when the light is introduced those cells will be damaged, leading to mild burns, some swelling and discomfort and possibly some scarring. Depending on the affected areas of the body such tissue damage can cause coughing, painful swallowing, stomach pain, painful or labored breathing or shortness of breath. As the damaged cells are replaced by healthy cells, however, the symptoms disappear, similar to how your mouth heals after you scorch it with hot soup.
Research continues into ways to expand the use of PDT on a broader range and greater diversity of cancers. New photosensitizers are under development as are new light delivery methods and the potential of this form of cancer treatment is exciting to researchers and cancer patients alike.