Photodynamic therapy is an experimental treatment for mesothelioma that uses drug activated by light to fight cancer cells. The combination of this treatment with surgery could improve the life expectancy of patients diagnosed with mesothelioma and has shown promising results for patients diagnosed with pleural mesothelioma. Photodynamic therapy, or in short PDT, kills cancer cells by using singlet oxygen generated by photosensitizing drugs and a light source. Most undergoing photodynamic therapy is a part of multimodal treatment and usually combined with surgery. Photodynamic therapy is usually used on patients in earlier stages, where cancer does not metastasize or spread further.
How does it work?
To put it simply, photodynamic therapy works by using three non-toxic elements to eradicate cancer cells. Photodynamic therapy combines a photosensitizer drug, oxygen, and certain light wavelengths to kills cancer. When uses separately, they can not kill cancer on their own, but when used simultaneously, they trigger a reaction that turns triplet oxygen into singlet oxygen. By doing so, the level of energy in oxygen is elevated and enabling it to kill cancer cells. Some cases also found out that photodynamic therapy can slow the growth of cancer by damaging certain blood vessels, which in exchange starve the tumor created by cancer cells to death. Another study also showed that photodynamic therapy could induce the body self-healing process by activating the immune system.
Currently, there are three photosensitizing elements that have been approved by the U.S. Food and Drug Administration (FDA). Porfimer sodium, which is sold as Photofrin, is the most commonly used photosensitizing elements nowadays. This kind of drug has been approved to use in two cancer treatments, which are esophageal cancer and non-small lung cancer (NSCLC). However, porfimer sodium still yet to be approved in use for mesothelioma. In order to get photodynamic treatment, patients diagnosed with mesothelioma need to participate in a clinical trial by consulting their doctor first.
Side Effects and Risks of Photodynamic Therapy
Side effects resulted from photodynamic therapy are generally mild, as the therapy is focused on a certain part of mesothelioma-affected organs and doesn’t have cumulative toxicity. Because of that, photodynamic treatment could be repeated several times without increasing its side effects. The most common side effects for patients undergoing photodynamic therapy are light sensitivity and swelling, which in some cases, could lead to difficulties in breathing. The other risks associated with this treatment include bronchitis, coughing up blood, fever, pneumonia, and breath shortness.
From all those risks, light sensitivity is the hardest one to deal with. It requires the most preventative measures and repeated care, which could be exhausting for the patient’s family. This reaction could last around 30 days after getting photodynamic treatment. In some cases, it’s reported that the patient still having this reaction up to three months after the last treatment. The light sensitivity could differ from one patient to another, depending on the size of the tumor and duration of the treatment. There are several precautions that could be used to deal with this reaction, which are complete errands after sunset, covering skin when doing outdoor activities, not using reading lamps, and limiting outdoors time when the sun in its highest position.