What Is Photodynamic Therapy?
Photodynamic therapy (PTD) is a promising new mesothelioma treatment still undergoing research in clinical trials. As a light-based treatment, photodynamic therapy works by aiming the light treatment directly at the cancer, killing mesothelioma cells while causing less damage to surrounding healthy cells.
Because mesothelioma is one of the toughest cancers to treat there is no one treatment that can cure it. Instead, doctors combine multiple, targeted treatments together in a specific order to build a tailored treatment plan that’s unique to each patient—including their genetic makeup. As a less invasive treatment method, photodynamic therapy is regarded as one of the best therapies to administer before or during surgery as part of a multimodal treatment plan.
Photodynamic therapy plays a supporting role in the surgical removal of mesothelioma tumors, and has shown to increase survival results.
There are both pros and cons to using photodynamic therapy to treat mesothelioma. Because mesothelioma is treatable but not curable, doctors are focused on modalities that work well with standard mesothelioma treatments like surgery, radiation and chemotherapy. Traditional treatments alone will not stop the spread of the disease, which is why it is the job of experimental treatments such as PTD to keep mesothelioma cells localized and prevent metastasis (spreading to distant sites).
How Does Photodynamic Therapy Work?
At a basic level, photodynamic therapy is an anticancer light treatment. Doctors use PDT to illuminate the full chest cavity, capture the mesothelioma tumors intraoperatively (during open surgery) to keep mesothelioma cells localized and prevent them from spreading to distant sites. PDT achieves this treatment goal with a laser light that activates a drug, targeting mesothelioma cells specifically so that it doesn’t harm healthy cells in the lung.
The process for photodynamic therapy follows these steps:
- A photosynthesizing solution (mthpc) is injected into the patient.
- Between one to three days, the solution is absorbed by the cancerous cells. This absorption acts as a target for the mesothelioma cells.
- In intraoperative photodynamic therapy, a light is applied, causing the photosynthesizer to chemically react, killing the mesothelioma cells.
- The tumor is removed and the light is used to find any remaining mesothelioma cells for removal.
Benefits of Photodynamic Therapy for Mesothelioma
There are definite advantages to using photodynamic therapy for mesothelioma. It has little known side effects and is essential in prolonging the life of those diagnosed with mesothelioma.
Overall, the benefits of photodynamic therapy include:
- Improving life expectancy up to several months, and in some cases, years
- Requiring fewer dosages than radiation
- Ensuring uniform illumination of the chest cavity, making it easier to localize the mesothelioma
- Acting as a cancer-centric treatment, meaning less damage to healthy cells
- Causing no long-term side effects.
- Allowing for repeated use on the tumor site with little side effects
- Generating fewer side effects than other modal treatments
Current and Ongoing Research Into Photodynamic Therapy
Because of PTD’s encouraging survival results, the American Cancer Society has dedicated immense research into exploring future advancements into this new treatment. There are hundreds of clinical trials involving photodynamic therapy that have occurred over the past two decades. Beyond that, the current and ongoing research into photodynamic therapy has shown that this is a viable treatment for mesothelioma.
Photodynamic Therapy With Pleurectomy With Decortication Surgery
A 2011 study from the Raymond and Ruth Perelma School of Medicine at the University of Pennsylvania concluded that the use of photodynamic therapy in conjunction with other treatments exposed a noticeable difference in their patients. According to Penn Medicine, “The results yielded by the radical pleurectomy and adjuvant (after surgery) PDT were superior to other studies of surgical treatment plans with patients of similar demographics.” Doctors found that the preservation of both lungs drastically helped in the survival rate of its patients, making PTD a key treatment element for this disease.
Photodynamic Therapy With Extrapleural Pneumonectomy Surgery
An initial experimental operation was performed on 28 patients in two Dutch cancer centers in 1996. Before extrapleural pneumonectomy (EPP) surgery (a pleural mesothelioma surgery that removes the lung, and portions of the diaphragm, and linking of the lung and heart), the photodynamic solution, mthpc, was administered to patients 4 or 6 days before the light would be applied. After that, patients were treated under a subdued light for two weeks.
After the EPP, isotropic light probes were strategically placed into transparent tubes to place a seam within the chest cavity. The study stated that “these isotropic probes measure the fluence rate delivered to the tissue, including both direct incident and scattered light from the tissue,” to better localize the pleural tumors. This allowed doctors to remove the highlighted mesothelioma cells, using a combination of the lights and the photosynthesizer solution. In this study, 50% of patients were able to localize the disease for an average of 9 months.
Photodynamic Therapy Side Effects
As with any medical treatment, photodynamic therapy has a list side effects. Though it does have certain side effects, PDT is still a less invasive option compared to some traditional methods.
Previously, researchers were concerned about the toxicity levels in patients who underwent PDT. However, with further research and trials, doctors have found ways to limit toxicity levels in patients who undergo PDT. Photodynamic therapy remains one of the lowest level treatments with very little side effects. In the most extreme cases, patients experience temporary light sensitivity and the mildest side effect involves itchiness or burning.
Photodynamic therapy side effects may include:
- Light sensitivity
- Itchiness or burning near administration area
- Shortness of breath
- Swollen skin
- Nausea or vomiting
Those patients who undergo photodynamic therapy should avoid exposure to direct sunlight following treatment. The side effects, if any, will last shorter than 30 days. Ambient, indoor lighting will help to breakdown the photosynthesizer which should speed up recovery time.
Undergoing Specialized Mesothelioma Treatment
Photodynamic therapy is one of many treatment that has the potential to change the lives of those living with mesothelioma. With few side effects and the possibility for a longer survival rate, it is one of the most prominent treatments in expanding research for mesothelioma.
Clinical trials are currently accepting patients diagnosed with mesothelioma in experimental photodynamic therapy testing. If you’re interested in participating in photodynamic therapy clinical trials, talk to your specialist or contact our Patient Advocates today.