What Is Photodynamic Therapy for Mesothelioma?

How Photodynamic Therapy Works

Photodynamic therapy (PDT) is a two-step treatment that combines a light-sensitive drug (photosensitizer) with a specific wavelength of light to destroy cancer cells. The photosensitizer is administered intravenously 24–48 hours before surgery, during which time it preferentially accumulates in tumor tissue. During surgery, after the surgeon performs maximal tumor debulking, a laser light is introduced into the chest cavity to activate the drug.

When the photosensitizer absorbs the light energy, it generates reactive oxygen species — highly toxic molecules that damage cancer cell membranes, blood vessels feeding the tumor, and trigger an immune response against the cancer. This mechanism allows PDT to target residual microscopic disease that surgery alone cannot remove.

PDT for Mesothelioma: Clinical Research

The University of Pennsylvania has been the leading institution investigating PDT for pleural mesothelioma. Phase I and II clinical trials have explored PDT as an adjunct to pleurectomy/decortication (P/D), with the photosensitizer activated intraoperatively after maximal surgical debulking. Results have been encouraging, with some studies reporting median overall survival exceeding 30 months for patients receiving the combined approach.

Early PDT studies used porfimer sodium (Photofrin) as the photosensitizer, but newer trials have investigated HPPH (Photochlor), a second-generation agent that causes less skin photosensitivity — a significant quality-of-life improvement for patients.

The PDT Treatment Experience

Patients receiving PDT typically undergo the following process: the photosensitizer is infused intravenously one to two days before surgery. The patient then undergoes surgical debulking (usually P/D). After tumor removal, the surgeon introduces fiber-optic light sources into the chest cavity. The light is systematically applied to all surfaces of the chest cavity for a precisely calculated duration to activate the drug and destroy residual cancer cells.

After treatment, patients must avoid direct sunlight and bright indoor light for several weeks (the duration depends on the specific photosensitizer used) to prevent skin burns. This photosensitivity period is the most notable side effect of PDT treatment.

Candidacy and Availability

PDT for mesothelioma is currently available primarily through clinical trials at specialized centers. Candidates are generally patients with early-stage pleural mesothelioma who are eligible for surgical debulking and have adequate organ function. Patients interested in PDT should discuss clinical trial eligibility with their oncologist or contact centers with active PDT research programs.

Because PDT is investigational, clinical trial participation may cover treatment costs. Patients whose mesothelioma was caused by asbestos exposure may also be entitled to legal compensation to cover travel and other expenses associated with seeking specialized treatment.