Primary Motility  Disorders of the  Esophagus
 The Esophageal
 Mucosa
 The
 Esophagogastric  Junction
 Barrett's
 Esophagus

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OESO©2015
 
Volume: Barrett's Esophagus
Chapter: Treatments
 

With the use of centering balloons, should thermal ablation (Nd:YAG laser) be associated to photodynamic therapy in long segments of Barrett's mucosa?

M. Panjehpour (Knoxville)

We typically treat patients using a 5 or 7-cm windowed balloon. We treat a maximum of 7cm of Barrett's mucosa in one session (one injection and laser treatment). In patients with Barrett's segments shorter than 7 cm, we typically ablate all Barrett's with one treatment session using a 7 cm balloon. In patients with longer segment of Barrett's, we treat 7 cm of the Barrett's with the worst pathology first. If the residual untreated Barrett's is longer that 1 or 2 cm in length and there is dysplasia in that area, we schedule patients for a second photodynamic therapy (PDT) treatment in 3-6 months (second injection with PhotofrinŽ). If the residual segment is short and there is no dysplasia (or there are small islands of Barrett's mucosa), we treat them with thermal ablation using Nd:YAG laser, typically starting 3 months after initial PDT treatment. We use contact probe (rounded probe) with water cooling. After thermal ablation, a follow-up endoscopy is performed in two days to evaluate the response. Additional thermal ablation may be performed again. We use 1315 Watts of power in CW mode using an SLT laser. Realizing that the majority of Barrett's esophagus is treated using balloon PDT, a discussion is included here on our balloon treatment.

Balloon light delivery for photodynamic therapy of Barrett's esophagus

Before development of balloons, cylindrical diffusers were used to treat a specific length of the esophagus. Initially, we [1] used a 2 cm cylindrical diffuser to treat patients with early invasive cancer in Barrett's esophagus.

Later, a balloon light delivery device was developed and tested by our group for treatment of Barrett's esophagus [2]. The balloon was constructed from a polyurethane membrane. It was determined that a windowed balloon with a diameter of 25 mm would effectively flatten the esophageal folds and would allow uniform illumination of specific length of the esophagus. Increasing the balloon diameter affected the blood flow in tissue and no PDT injury was induced even at much higher light doses [3].

This balloon with a 2 or 3 cm window was first used clinically to treat four patients [4]. A 2 cm cylindrical diffuser was used in the 2 cm windowed balloon. A 2.5 cm cylindrical diffuser was used in the 3 cm windowed balloon (3 cm diffusers were not available). Long segments were treated sequentially by repositioning of the balloon. This balloon design was used to determine the proper light dosimetry and develop the methodology [5]. The power density from the fiber was 400 mw/cm of length of diffuser. In the first patient, the position of balloon was checked using measurements on the shaft of the balloon. This technique was found to be unreliable. For all other patients, the scope was passed alongside the balloon shaft and the position of the balloon was verified using a marker on the shaft of the balloon. The marker was 3 cm proximal to the proximal edge of the balloon window. Thus, by monitoring the position of the marker using scope measurements, the position of the window was easily verified.

Treatment of long segments of Barrett's using a 2 cm or 3 cm windowed balloon required sequential treatments of the esophagus during each session. Typically, it is difficult to avoid overlapping of the treatment fields. A 5 cm long windowed balloon was developed to allow treatment of a longer segment of the Barrett's esophagus without repositioning of the balloon [6]. A flexible 5 cm cylindrical diffuser (Rare Earth Medical, Inc.) was used in the 5 cm windowed balloon. The power density from the diffuser was 400 mw/cm with a total power of 2,000 mw. In addition, the balloon design was modified for guidewire positioning of the balloon in the esophagus. Using this design, first a standard guidewire was passed into the stomach. The balloon was passed over the guidewire and positioned into the stomach. The scope was passed alongside the balloon shaft. The balloon was withdrawn until the marker on the shaft was at the desired location in the esophagus, noting that the marker is 3 cm proximal to the proximal edge of the balloon window. The guidewire was withdrawn and the balloon was inflated. The cylindrical diffuser was passed into the central channel of the balloon to a premeasured depth, aligning the diffuser with the window. The central channel of the balloon assembly was then flushed with saline through a flush-inlet to wash any contaminants inside the central channel. Contaminants can interfere with the light from diffuser causing irreversible damage to the fiber and the balloon. The laser was then activated.

Finally, balloons with a window length of 7 cm were developed that allowed a longer segment of Barrett's to be treated [7]. A 7 cm flexible cylindrical diffuser was used inside the balloon shaft as the light source (Rare Earth Medical). The power density from the diffuser was 400 mw/cm, or 2,800 mw total power for a 7 cm diffuser. Currently, a maximum of 7 cm of the esophagus is treated in one session. The light dose is 175-200 J/cm using this balloon requiring a treatment time of 438-500 seconds.

The above balloon was modified for the phase III multicenter study for treatment of high-grade dysplasia (HGD) in Barrett's esophagus (sponsored by QLT PhotoTherapeutics). The interior surface of the distal and proximal capped portions of the balloon were coated with a reflective material (Wilson-Cook Medical Inc., Winston-Salem, NC). A cylindrical diffuser 2 cm longer that the window length was used inside the central channel. The cylindrical diffuser extended 1 cm proximally and 1 cm distally beyond the window margins. Using this diffuser/balloon configuration, the uniformity of light emitted from the balloon window was improved. In addition, laboratory testing and canine studies showed that the light intensity emitted from the balloon window was 1.5 times higher using the reflective balloons design compared to that from the initial balloon design (unpublished data). This allowed using a lower power density (and power) from the diffuser while achieving the same intensity of light emitted from the balloon window. The power density of 270 mw/cm from diffuser provided a similar light intensity from the window as that provided with the original balloon [7]. Using this balloon, a light dose of 130 J/cm is used for treatment of HGD in Barrett's esophagus (phase III study). The reflective balloons are available in window lengths of 3 cm, 5 cm and 7 cm, and are currently provided by QLT PhotoTherapeutics for the phase III study. A 5 cm diffuser is used in the 3 cm windowed balloon, a 7 cm diffuser in the 5 cm windowed balloon, and a 9 cm diffuser in the 7 cm windowed balloon. The above diffusers are provided by QLT PhotoTherapeutics for Phase III study. The balloon material was changed to non-stretchable polyethylene terephthalate to achieve a balloon diameter of 25 mm even at very high balloon pressures. The original balloon was constructed from polyurethane that had the potential for membrane stretching, resulting in increased balloon diameter at higher pressures. The QLT sponsored study is closed to patient accrual.

References

1. Overholt BF, Panjehpour M, Teffteller E, et al. Photodynamic therapy for treatment of early adenocarcinoma in Barrett's esophagus. Gastrointest Endosc 1993;39:73.

2. Panjehpour M, Overholt BF, DeNovo RC, et al. Centering balloon to improve esophageal photodynamic therapy. Lasers Surg Med 1992;12:631.

3. Overholt BF, Panjehpour M, DeNovo RC, et al.Balloon photodynamic therapy of esophageal cancer: effect of increasing balloon size. Lasers Surg Med 1996;18:248.

4. Overholt BF, Panjehpour M. Barrett's esophagus: photodynamic therapy for ablation of dysplasia, reduction of specialized mucosa, and treatment of superficial esophageal cancer. Gastrointest Endosc 1995;42:64.

5. Overholt BF, Panjehpour M. Photodynamic therapy in Barrett's esophagus. J Clin Laser Med Surg 1996;14:245.

6. Overholt BF, Panjehpour M. Photodynamic therapy for Barrett's esophagus. Gastrointest Endosc Clin North Am 1997;7:207.

7. Overholt BF, Panjehpour M, Haydek JM. Photodynamic therapy for Barrett's esophagus: follow-up in 100 patients. Gastrointest Endosc 1999;49:1.


Publication date: August 2003 OESO©2015