Photo therapy a success in esophageal cancer study

Gastroenterologists at Mayo Clinic in Jacksonville, Fla., report photodynamic therapy (PDT) appears to destroy the abnormal tissue of Barrett’s esophagus as well as superficial esophageal cancer. They report the results of treating 48 patients with PDT in the November 2002 issue of Mayo Clinic Proceedings.

After monitoring patients with periodic endoscopy for a median of 18.5 months, the physicians documented complete elimination of the abnormal tissue and the cancerous cells in 27 patients after one course of PDT. Follow-up endoscopy after PDT revealed 21 patients had some residual Barrett’s tissue. Twenty of these patients underwent a follow-up procedure that eliminated the remaining Barrett’s tissue with heat energy. PDT failed to completely ablate one patient’s superficial adenocarcinoma. This patient later had surgery to remove his esophagus. The article’s authors found that the shorter the segment of Barrett’s esophagus, the more likely it was to be totally destroyed using PDT.

Here’s how PDT works. Patients are given an injection of a photosensitizing drug called porfimer sodium (Photofrin). Cells in the body absorb this drug. Normal cells get rid of it, but the drug tends to collect in premalignant and malignant cells. Two days after the injection of Photofrin, physicians insert and endoscope into the sedated patient’s esophagus. An endoscope is a thin, flexible tube with a miniature camera on its tip. Physicians deliver a specific wavelength of red laser light through the endoscope to the targeted cells. The laser light destroys the Photofrin-containing cells. Normal esophageal cells grow back in their place.

The esophagus is a muscular tube that carries food and liquids from the mouth to the stomach. Gastroesophageal reflux disease (GERD), commonly called acid reflux, happens when the acidic contents of the stomach back up into the esophagus. GERD is a common medical condition affecting about 15 percent of adults in the United States.

Barrett’s esophagus is less common, but long-term acid reflux is thought to cause this pre-malignant condition, in which part of the smooth, pink lining of the esophagus is replaced with darker, rougher tissue similar to that of the intestine. People with Barrett’s esophagus, in turn, are much more likely to develop a form of cancer of the mucous secreting cells of the esophagus (esophageal adenocarcinoma) than people who don’t have Barrett’s esophagus.

Surgical removal of the esophagus (esophagectomy) has been the standard treatment for patients with a high degree of tissue change with Barrett’s esophagus and esophageal adenocarcinoma. However, it is not uncommon for patients who survive the surgery to experience complications and a decreased quality of life. In addition, some patients are not good candidates for the surgery to begin with because of age or other health problems.

Physicians have been using Photofrin PDT since 1995 to treat terminally ill patients with esophageal cancer who have difficulty swallowing. In the past few years they have also begun to use PDT to treat patients with Barrett’s esophagus and superficial esophageal cancer who are not good candidates for esophagectomy.

Dr. Herbert Wolfsen, one of the authors of the article in Mayo Clinic Proceedings, says long-term studies are needed to prove the effectiveness of Photofrin PDT as an alternative to surgery. “Right now we have to follow up patients carefully,” Wolfsen says, “because we’re not able to look beneath the lining of the esophagus and say for certain that there are no Barrett’s cells left. We’re getting close to a follow up of two years with this group of patients, and with any cancer prevention treatment we need a follow-up of about five years before you can definitively say that we’ve been able to reverse the problem.”

Still, Wolfsen says his hope is that Photofrin PDT to treat Barrett’s esophagus will take its place as an accepted and reliable treatment alternative to esophagectomy for many patients.