Photodynamic therapy is an emerging treatment for malignant pleural mesothelioma and malignant peritoneal mesothelioma. It uses light energy in conjunction with a photosensitizing drug to kill cancer cells. This approach is one of several new, targeted treatments for mesothelioma.1
How Photodynamic Therapy Works
The first step of the treatment is administration of a photosensitizing drug, such as Photofrin, through a patient’s vein. The drug is selectively taken up by cancerous cells. Next, surgery is performed to access the affected cavity. In the case of malignant pleural mesothelioma, that would be the thoracic cavity, and in the case of malignant peritoneal mesothelioma, that would be the abdominal cavity. Once access to the cavity is achieved, surgical removal of any visible tumors, known as cytoreductive surgery, may or may not be performed. Then, laser light of a particular wavelength is delivered to the cancerous tissues. This light reacts with Photofrin in the cancerous cells to produce oxygen free radicals and other substances that kill the cancerous cells.
Benefits and Advantages of Photodynamic Therapy
Photodynamic therapy has been found to significantly extend survival for individuals with malignant peritoneal mesothelioma. Moreover, photodynamic therapy may be safer and more tolerable than other intraperitoneal therapies, such as hyperthermic intraperitoneal chemotherapy. These advantages of photodynamic therapy are believed to be due to its greater selectivity for cancerous cells.2
Who Qualifies for Photodynamic Therapy
Before photodynamic therapy is performed, a patient’s doctor will determine whether they are healthy enough to withstand surgery and its potential complications and live long enough to benefit from the treatment. The doctor will evaluate the health of the patient’s heart and lungs with electrocardiogram and pulmonary function tests. He or she will also assess the individual’s other health conditions and overall health status. Finally, imaging studies and other diagnostic tests and necessary procedures will be performed to determine the size of the patient’s tumors and stage of their disease. Because light must be able to penetrate a tumor completely for photodynamic therapy to be successful, individuals with large tumors may not qualify for this treatment.
For patients with poor overall health or more advanced disease, photodynamic therapy would be futile and would only cause them more pain. In this case, a palliative and multimodal approach is initiated to provide the patient with more tolerable therapies, such as systemic chemotherapy, radiation, or even experimental treatment, and the best combination of these therapies to extend their lifespan and improve their quality of life.