**2. Contraindications of photodynamic therapy**

Photodynamic therapy and porfimer sodium, in particular, has a set of contraindications that are worth noting. Porfimer sodium and really any photodynamic therapy cannot be used therapeutically in individuals with porphyria [14, 15]. These individuals have one of a group of diseases that allow for an increased accumulation of porphyrins utilized by the human body in hemoglobin production, and these porphyrins increase photosensitivity [16]. Given the foundation of photodynamic therapy is localized photosensitivity by means of porphyrins, this contraindication is reasonable [3]. Other contraindications are existing tracheoesophageal/bronchoesophageal fistulas [17]. These are abnormal connections between the airway and the esophagus. Tumor eroding into the airway are also contraindicated given the risks that will be described below [17]. Additionally, given the delayed time scale of photodynamic therapy, usage in emergency situations when therapy must be delivered immediately would not be optimal [17].
