Tuesday, April 03, 2007
Hospital is one of only a few facilities to offer new freezing technique to destroy abnormal cells
Doctors at the University of Maryland Medical Center are using a new cryotherapy technique to treat cancerous and pre-cancerous conditions of the esophagus. The medical center is one of only a handful of facilities in the world to offer the CryoSpray ablation procedure and one of three centers conducting clinical research to determine its effectiveness.
In this novel outpatient treatment, doctors spray liquid nitrogen onto abnormal or cancerous tissue using specially designed equipment threaded into the esophagus through an endoscope. An endoscope is a thin, fiber-optic instrument inserted through the mouth to enable a doctor to see inside the digestive tract. The liquid nitrogen freezes the tissue, which then thaws and ultimately sloughs off, providing an opportunity for normal tissue to grow back in its place.
Bruce D. Greenwald, M.D., a gastroenterologist at the medical center and an associate professor of medicine at the University of Maryland School of Medicine, is leading this pilot study. He has treated 22 patients since April 2006. The majority were diagnosed with a pre-cancerous condition known as Barrett’s esophagus with high-grade dysplasia (significant abnormalities in the
esophageal lining). Other patients in the study had esophageal cancer in its early stages and were
not candidates for conventional medical or surgical treatment.
"The early results are very promising. The patients diagnosed with high-grade dysplasia and early-stage cancer are responding well to the treatment," says Dr. Greenwald, adding that it is too early to draw any definite conclusions about the long-term effectiveness of the procedure. "We want to follow these patients for a longer period of time, at least a year for the cancer patients and two years for those with high-grade dysplasia."
The CryoSpray ablation system is approved by the U.S. Food and Drug Administration. The treatment sessions take an average of 10 to 15 minutes, and patients receive moderate sedation for the procedure, which is performed on an outpatient basis in the gastrointestinal endoscopy suite. Typically, several abnormal areas of the esophagus are treated during each session. Each area is frozen and thawed multiple times. Sessions are repeated every two to six weeks, depending on the extent of the disease and the patient’s response to treatment. Patients so far have required an average of three treatments.
In Barrett’s esophagus, the normal lining of the esophagus (the muscular tube leading from the mouth to the stomach) is replaced by tissue similar to that found in the intestine. The condition is associated with chronic heartburn, or gastroesophageal reflux disease, that has damaged the esophagus. Doctors examine the tissue under the microscope to determine the extent of the disease.
In high-grade dysplasia, the tissue is severely abnormal and may develop into esophageal cancer. Dr. Greenwald says that patients with high-grade dysplasia carry about a 30 percent risk of developing esophageal cancer within five years. Standard treatments include surgery to remove the esophagus and photodynamic therapy, which kills abnormal cells using a "cool" laser and light-
sensitizing drug. In addition to cryotherapy, other ablation techniques performed through an endoscope use extreme heat, radio waves or a cutting procedure to remove the esophageal lining.
Dr. Greenwald uses photodynamic therapy to treat patients with high-grade dysplasia and some early-stage cancers, but adds that there are significant side effects, including extreme sensitivity to light. Patients must cover their skin completely for four to six weeks after treatment to avoid severe sunburn. "Cryotherapy is a less painful and more convenient treatment for patients compared to photodynamic therapy," he says.
For some people with early esophageal cancer who aren’t eligible for surgery or have failed to respond to chemotherapy and radiation, the new freezing technique may be a good alternative,
Dr. Greenwald says. "We see a number of patients, particularly older people, who are not able to have surgery or are too ill to tolerate other therapies. Now, we can offer them a treatment option where previously there was none," he says. He adds that side effects from the cryotherapy are minimal. "Most people have minor soreness or none at all," he says.
Once the treatment is complete, Dr. Greenwald examines the esophagus through the endoscope and takes tissue samples, which are scrutinized under a microscope to make sure that the abnormal cells are gone. He notes that patients must still be closely monitored because -- as with any technique in which only the superficial esophageal lining is removed -- abnormal or cancerous cells may start re-growing underneath the normal tissue.
The pilot study is sponsored by a grant from the Maryland Industrial Partnerships
Program (www.mips.umd.edu) and by CSA Medical, Inc., a Baltimore-based company that manufactures the CryoSpray ablation system (www.csamedical.com). The technology was developed by a gastroenterologist at the National Naval Medical Center in Bethesda. The naval hospital and the Cleveland Clinic are also testing the procedure in clinical studies.
For more information on the University of Maryland study, patients can call (800) 492-5538.
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