Photodynamic therapy strictures: who is at risk?

Laryngotracheal Stenosis as a Complication of Photodynamic Therapy

Objective:

Photodynamic therapy (PDT) has been proposed as an effective treatment for mucosal carcinomas such as early-stage laryngeal squamous cell carcinoma. Its advantage over other conventional modalities (surgery and chemoradiation) lies in its ability to treat disease while preserving the function and structure of the larynx. While not FDA-approved in the United States, it is used in some countries as a treatment for laryngeal cancer and is an area of active investigation. This report documents a severe complication of tracheostomy-dependent laryngotracheal stenosis resulting from PDT.

Methods:

Methods include a case report and review of the literature.

Results:

A 65-year-old male presented with severe stenosis of the supraglottic, glottic, and subglottic larynx following successful treatment of his laryngeal carcinoma with PDT. His presentation, staged airway reconstruction, and outcome are detailed.

Conclusion:

PDT is a minimally invasive technique which in early clinical trials has matched the effectiveness of conventional therapies for treating early head and neck squamous cell cancers. It uses a photosensitizing agent that is retained by tumor cells, allowing for the selective destruction of neoplastic cells. Permanent sequelae following treatment have rarely been reported; the most commonly described adverse effects include pain, hoarseness, and phototoxicity. However, our case report discusses the potential for significant laryngotracheal stenosis requiring airway reconstruction following PDT.

Metal stenting to resolve post-photodynamic therapy stricture in early esophageal cancer

Photodynamic therapy (PDT) is an established endoscopic technique for ablating Barrett’s esophagus with high-grade dysplasia or early-stage intraepithelial neoplasia. The most common clinically significant adverse effect of PDT is esophageal stricture formation. The strictures are usually superficial and might be dilated effectively with standard endoscopic accessories, such as endoscope balloon or Savary dilators. However, multiple dilations might be required to achieve stricture resolution in some cases. We report the case of stricture that recurred after dilation with a bougie, which was completely relieved by a self-expandable metal stent.

Monte carlo model of stricture formation in photodynamic therapy of normal pig esophagus

Photodynamic therapy (PDT) is FDA-approved for use in patients with Barrett's esophagus using porfimer sodium (2 mg per kg) and a recommended light dose of 130 J cm(-1) for high grade dysplasia. Despite uniform drug and light doses, the clinical outcome of PDT is variable. A significant number of PDT cases result in esophageal strictures, a side effect related to excessive energy absorption. The purpose of this project was to model esophageal stricture formation with a Monte Carlo simulation. An original multilayer Monte Carlo computer simulation was developed for esophageal PDT. Optical absorption and scattering coefficients were derived for mucosal and muscle layers of normal porcine esophagus. Porfimer sodium was added to each layer by increasing the absorption coefficient by the appropriate amount. A threshold-absorbed light dose was assumed to be required for stricture formation and ablation. The simulation predicted irreversible damage to the mucosa with a 160 J cm(-1) light dose and damage to the muscle layer with an additional 160 J cm(-1) light dose for a tissue porfimer sodium content of 3.5 mg kg(-1). The simulation accurately modeled photodynamic stricture formation in normal pig in vivo esophageal tissue. This preliminary work suggests that the absorbed light threshold for stricture formation may be between 2 and 4 J per gram of tissue.

Patient predictors of esophageal stricture development after photodynamic therapy

BACKGROUND & AIMS

The most common significant adverse event after photodynamic therapy (PDT) with porfimer sodium is esophageal stricture formation. This study assessed whether pretreatment variables, including prior endoscopic therapy for Barrett's esophagus, are associated with post-PDT stricturing.

METHODS

Data from all patients who had undergone PDT with porfimer sodium for Barrett's esophagus with high-grade dysplasia, intramucosal carcinoma, or T1 cancer at our institution since 1997 were reviewed.

RESULTS

One hundred sixteen patients underwent 160 courses of PDT. The incidence of stricture formation after index PDT was 16% (19/116). For all PDT courses, the overall incidence of stricture was 23% (37/160). Stricture rate was significantly higher after a second PDT course compared with index PDT (43% vs 16%, P = .0007). There was no association between post-PDT stricture development and age, gender, body mass index, or prior endoscopic mucosal resection. Patients who developed a stricture had a longer length of Barrett's esophagus before treatment than those who did not develop a stricture (7.7 vs 5.7 cm for index PDT only, P = .025; 7.4 vs 5.7 cm for all PDT courses, P = .007). Length of Barrett's esophagus, multiple PDT courses, and presence of intramucosal carcinoma on pretreatment pathology were independent predictors of post-PDT stricture in a stepwise logistic regression analysis controlling for treatment variables, including treatment length.

CONCLUSIONS

An increased risk of stricture development was seen after multiple courses of PDT. An association between post-PDT stricture and length of Barrett's esophagus but not treatment length was also found. Endoscopic mucosal resection did not appear to influence the likelihood of stricture development after porfimer sodium-based PDT.