Hu et al., J Anal Bioanal Tech 2014, S1 http://dx.doi.org/10.4172/2155-9872.S1-e001 ISSN: 2155-9872 JABT, an open access journal Photodynamic Therapy-Cancer J Anal Bioanal TechPhotodynamic therapy (PDT) is a treatment modality involving photoactivatable chemicals (called photosensitizers), light and tissue oxygen [1][2][3][4][5][6]. PDT has clinical applications in the treatment of a variety of solid cancers [4,7-21], including but not limited to those of lung, skin, breast, head and neck, digestive tract, pancreas, liver, bladder, ovary, prostate and brain. In addition, there are many clinical applications of PDT for treatment of a wide range of non-cancerous conditions, such as bacterial and fungal infections; hyperproliferative or inflammatory conditions, such as macular degeneration or psoriasis; and premalignant conditions, such as actinic keratosis [22] and Barrett's esophagus [23]. To achieve better therapeutic efficacy, new photosensitizers and novel light sources are continuously being developed, and the mechanisms of action are becoming better understood [24,25]. To achieve improved tumor selectivity and to reduce side effects in the treatment of cancer, the concept of targeted photodynamic therapy has been successfully developed by attaching specific functionalities to the photosensitizer, such as antibodies recognizing tumor antigens [26,27], or ligands and peptides to recognize receptors [28], which could be selectively expressed on one of the two major tumor compartments, either on the malignant cells or on tumor neovasculature. To achieve better efficacy than PDT that is targeted to a single tumor compartment (stPDT), a recent editorial [29] in this Journal summarized a new PDT approach (Figure 1), which was designed for dual targeting of photosensitizers (dtPDT) to both malignant cells and neovasculature [30,31] by conjugating photosensitizers to a protein, factor VII, the natural ligand for tissue factor. This approach allows for dual targeting of malignant cells and of tumor neovasculature, both of which either overexpress or selectively express tissue factor [30][31][32][33], respectively.In this special issue on PDT-Cancer, PDT scientists and experts worldwide contributed seven peer-reviewed articles. These review and research articles broadly cover the use and applications of PDT for cancer, for infections and for inflammatory conditions. Menon and Stafinski [34] in Canada thoroughly reviewed reports of clinical applications and clinical trials of PDT for the treatment of different types of cancers that were published in English between January 1997 and June 2011. They summarized a total of 266 studies, which involved 11,427 patients and 34 different types of cancer in diverse organs, such as anal and perianal cutaneous cancers, as well as cancers of the bile duct, bladder, brain, breast, cervical, esophageal, eye, gastrointestinal, head and neck, lung, peritoneal cavity, colorectal, liver, ovary, pancreas, prostate, skin, vulva, etc. Tsipursky, Churgin, Conway and Peyman [35] in the Uni...