For people with early cancer of the larynx, the standard treatment can be grueling: a biopsy in an operating room followed by a six-week course of radiation that may lead to permanent hoarseness or speech impairment.
The therapy, which uses heat from the laser to destroy the tumor’s blood supply and cancer cells, damages surrounding tissue far less than radiation and different types of lasers.
It has been tested in only 28 patients, all at Massachusetts General Hospital in Boston. Yet the initial findings hold promise because the laser was the patients’ only treatment and none have had a recurrence or needed surgery or radiation after a mean follow-up of 27 months, the team’s leader, Dr. Steven M. Zeitels, said in an interview. The longest is more than five years.
Other experts expressed cautious optimism about the findings from the pilot study, which the Harvard team reported May 1 at a meeting of the American Broncho-Esophagological Association in Orlando. The scientific report involved the first 22 of the 28 patients.
The procedure “represents a radically new approach to treatment of these cancers,” said Dr. Gregory A. Grillone, an otolaryngologist at Boston University School of Medicine. Dr. Grillone, who directs the Center for Voice and Swallowing at Boston Medical Center, spoke in an interview after hearing Dr. Zeitels’s presentation at the meeting.
Dr. Zeitels agreed with Dr. Grillone and other experts who said the procedure must now be tested on more patients in other hospitals and monitored for a longer period before it could become a standard therapy. Longer studies comparing the new technique with standard therapy are needed to confirm that it is equally effective in curing the cancers.
Even then, only an estimated 2,000 of the 11,300 people, mostly men, who develop laryngeal cancer in this country each year seem likely to be candidates for the laser therapy.
Those eligible would be patients whose cancer was detected when the malignant growth was small and limited to one or both vocal cords in a form known as glottal cancer, which accounts for about 65 percent of new laryngeal cancers. An estimated one-third of glottal tumors are detected in an early stage, Dr. Zeitels said.
If studies confirm the early findings, then researchers must determine which kinds of laryngeal cancers and which patients are appropriate for the laser treatment, said Dr. Andrew Blitzer, a professor of otolaryngology at Columbia and director of the New York Center for Voice and Swallowing Disorders.
The initial clue to cancer of the vocal cords is often persistent hoarseness. The cancer most commonly develops among smokers, who are prone to developing additional types of cancer in the head and neck.
When radiation is used for laryngeal cancer, it cannot ordinarily be used again if other cancers develop nearby. So the laser procedure offers a strong additional advantage, Dr. Zeitels said — preserving radiation as a treatment option for laryngeal cancer patients who later develop head and neck cancers.
Treatment for laryngeal cancer has progressed slowly. Surgery was the only treatment until the advent of radiation in the early 20th century. In 1971, lasers began to be used for a noncancerous vocal cord problem, and different kinds of lasers have followed for vocal cord cancer.
The concept of the laser therapy derives from the work of the late Dr. Judah Folkman, the pioneering Harvard scientist who theorized that tumors could be starved by stopping angiogenesis — the process by which tumors stimulate formation of new blood vessels to feed themselves.
The new procedure relies on a type of laser called the pulsed photoangiolytic KTP. Its green light selectively destroys the blood vessels feeding the tumor without burning the vocal cords. “It’s like sandblasting the surface with light,” Dr. Zeitels said.
Vibration of the vocal cords is essential for good voice and speech. By preserving vocal cord function, the laser treatment allows the cords to vibrate, “not perfectly, but substantially better” than before patients had the procedure, Dr. Zeitels said.
“All the prior laser treatments would burn the vocal cords,” he said, “and when that happens they do not vibrate normally.”
Dr. Zeitels said his team had long used pulsed angiolytic lasers for a variety of benign laryngeal problems, including a precancerous condition called dysplasia.
The pulsed angiolytic laser has allowed ear, nose and throat specialists to treat most laryngeal dysplasias under local anesthesia in an office instead of general anesthesia in an operating room.
But “treating cancer is not the same as treating dysplasia,” he said, and he moved cautiously before using the laser for cancer.
One step was to alter the KTP laser to deliver the light in pulses to the soft tissue of the vocal cords, allowing the tissue to cool between bursts. The cooling prevented significant heat-induced scarring.
The first patient was John Ward, a professor at the Kellogg School of Management at Northwestern University. After several years in which he was hoarse and needed a microphone to give lectures, he said in a recent interview, doctors detected cancers on both vocal cords.
Dr. Ward read up on the disease and consulted with Dr. Zeitels and other specialists about his treatment options. Dr. Zeitels suggested the new laser therapy in extensive discussions, and Dr. Ward agreed.
The two tumors differed in size, so Dr. Zeitels said he aimed at preventing scars that might fuse the cords. He treated the larger cancer with a carbon dioxide laser and the smaller one with the angiolytic laser.
Six weeks later, both tumors had disappeared.
Dr. Ward said the treatment had saved his career — that he now had about 80 percent of his original quality of voice and 90 percent of its strength, and no longer needed a microphone to lecture.
Typically, patients are treated two to three times spaced six weeks apart to reduce the tumor’s size, Dr. Zeitels said. He added that it was generally safe to leave early vocal cord cancers in place for that period of time because they rarely spread at this stage.
Standard acoustic and other tests are performed in a sound-treated room before the procedure and monitored thereafter.
Urologists have used angiolytic lasers in a different way to burn prostate tissue, Dr. Zeitels said. For the vocal cords, “the procedure is dead-on easy” and could be performed by any ear, nose and throat specialist who learns to use the $70,000 laser, he said.
He also speculated that the angiolytic laser might eventually be adapted for treatment of cancers of the esophagus, bladder, cervix, windpipe and parts of the lungs.
Dr. Zeitels said that he had not received industry financial support for his research and that his team’s paper would be published in The Annals of Otology, Rhinology and Laryngology in July.
Posts
No comments:
Post a Comment