Photodynamic therapy for lung cancer and malignant pleural mesothelioma

Photodynamic therapy (PDT) is a form of non-ionizing radiation therapy that uses a drug, called a photosensitizer, combined with light to produce singlet oxygen ((1)O2) that can exert anti-cancer activity through apoptotic, necrotic, or autophagic tumor cell death. PDT is increasingly being used to treat thoracic malignancies. For early-stage non-small cell lung cancer (NSCLC), PDT is primarily employed as an endobronchial therapy to definitively treat endobronchial or roentgenographically occult tumors. Similarly, patients with multiple primary lung cancers may be definitively treated with PDT. For advanced or metastatic NSCLC and small cell lung cancer (SCLC), PDT is primarily employed to palliate symptoms from obstructing endobronchial lesions causing airway compromise or hemoptysis. PDT can be used in advanced NSCLC to attempt to increase operability or to reduce the extent of operation intervention required, and selectively to treat pleural dissemination intraoperatively following macroscopically complete surgical resection. Intraoperative PDT can be safely combined with macroscopically complete surgical resection and other treatment modalities for malignant pleural mesothelioma (MPM) to improve local control and prolong survival. This report reviews the mechanism of and rationale for using PDT to treat thoracic malignancies, details prospective and major retrospectives studies of PDT to treat NSCLC, SCLC, and MPM, and describes improvements in and future roles and directions of PDT.