Photodynamic Therapy (PDT)
Photodynamic therapy (PDT) is another way to treat Barrett’s esophagus with high grade dysplasia or early cancer. PDT was one of the first successful alternatives to surgery for Barrett’s with HGD.
Photodynamic therapy has a few steps:
- A photosensitizing chemical is given. The two commonly used chemicals are intravenous porfimer sodium (Photofrin), which is most commonly used in the US and oral 5-aminolevulinic acid, which is used in Europe. The photosensitizer spreads throughout the body and locates in rapidly dividing cells, like cells in the esophagus with Barrett’s and dysplasia
- Upper endoscopy is performed, often 2 days after the photosensitizer is given. A special laser fiber is passed through the channel in the endoscope and the laser light causes a photochemical reaction in the cells containing the photosensitizing chemical. This destroys the BE and dysplasia.
- 2 days later, upper endoscopy is often repeated, to look for areas that weren’t completely treated by session #1. Any areas that were missed are retreated during this endoscopy
A large randomized multicenter controlled trial of photodynamic therapy was published in 2005. 208 patients with Barrett’s esophagus and high grade dysplasia were randomized either to porphyrin PDT plus a proton pump inhibitor (PPI -acid suppression medication) or to PPI alone.
- For the patients randomized to PDT, 77% had complete ablation of their HGD and 52% had complete ablation of all their BE.
- 39% of the PPI-only patients had resolution of their HGD, but only 7% had regression of their BE.
- 28% of the patients in the PPI-only group developed cancer while 13% of patients receiving PDT eventually developed cancer.
- 5-year follow up of the patients showed that the cancer rates were not different than listed above (29% of the PPI- only patients vs. 15% of the PDT patients). The patients treated with PDT who did eventually get cancer didn’t develop cancer as soon as the PPI-only patients.
There are some complications of photodynamic therapy that are typically discussed with patients before beginning treatment. Everyone getting PDT is at risk for severe sunburn – the photosensitizing chemical also collects in the skin, so avoiding sunlight is very important. The photosensitivity typically lasts about 8 weeks. About 1/3 of patients getting PDT may develop a stricture, or narrowing of the esophagus, in the area that was treated. These can be treated with esophageal dilation, although more than one dilation session is usually needed. Chest pain and difficulty swallowing are not uncommon right after the procedure. And like other ablation techniques, there is always a concern about ‘buried Barrett’s', or left-over BE tissues that gets buried under the new squamous (normal) esophageal mucosa.
This study was a large, well-designed study that shows PDT is effective for treating BE with high grade dysplasia. There are other studies that show it is an effective option for treating Barrett’s with dysplasia and early cancer. As with any treatment, it’s important to discuss options with your doctor to determine which treatment would be best for you.
Here are a few references for the studies mentioned:
Overholt BF, et al. Photodynamic therapy with porfimer sodium for ablation of high-grade dysplasia in Barrett’s esophagus: international, partially blinded, randomized phase III trial. Gastrointestinal Endoscopy 2005;62(4):488-98.
Overholt BF, et al. Five-year efficacy and safety of photodynamic therapy with Photofrin in Barrett’s high-grade dysplasia. Gastrointestinal Endoscopy. 2007 Sep;66(3):460-8.
posted by Kerry Dunbar, MD