An adaptation of a laser procedure developed to treat noncancerous abnormalities on the vocal cords has found preliminary success in treating cancerous tumors of the cords. The methodology uses pulses of green laser light to destroy the tumors selectively, without burning or otherwise damaging the rest of the vocal cords. If it maintains its early promise, the technique will offer a simple, cheaper, and less time-consuming alternative to the standard treatments of surgery and radiation therapy.
In an initial study by Steven Zeitels, professor of laryngeal surgery at Harvard Medical School and director of the Voice Center at Boston’s Massachusetts General Hospital, all 22 patients were free of cancer at least two years after a new angiolytic laser treatment, without removal of vocal-cord tissue or loss of voice quality. A number of patients were free of disease for over five years. Zeitels reported on the research at a recent meeting of the American Broncho-Esophagological Association. A paper describing the work appears in The Annals of Otology, Rhinology and Laryngology in July.
27 years of laser treatments
Doctors have used lasers since 1971 to treat noncancerous growths in the larynx, which contains the vocal cords. Zeitels himself has gained fame for his microsurgical treatment of vocal-cord disorders in actress Julie Andrews, operatic singer Carol Vaness, and rock singer Steve Tyler of Aerosmith. The idea of applying the same treatment to malignant tumors came to him when John Ward, a professor at Northwestern University, consulted him in late 2002 after learning he had cancers on both vocal cords.
The basic concept stems from research by Judah Folkman of Harvard Medical School, who died in January. Folkman argued that physicians could destroy tumors by stopping angiogenesis, the process whereby cancerous tumors create new blood vessels on which they feed. Pulses of laser light, Zeitels reasoned, could heat up and destroy the tumors and their blood vessels without significantly burning the underlying normal vocal cords to which cancers were attached, or leaving scars that could damage vocal-cord vibration necessary for voice. The team first used the yellow pulsed dye lasers that had replaced the carbon dioxide lasers used initially for laryngeal procedures. Then the group switched to a green potassium titanyl phosphate (KTP) laser that is less likely to damage healthy tissue. Zeitels adapted the KTP laser to deliver its light precisely enough to allow the tissue to cool between pulses, thereby reducing the possibility of scarring.
Treatment of John Ward proved remarkably successful. Both his tumors had disappeared six weeks after the treatment. Eventually his voice regained 80% of its quality and 90% of its strength. When he lectured, Ward was able to give up the microphone that he had used for years as the tumors made him hoarse.
Zeitels’s procedure for early vocal-cord cancers typically involves two sessions in the operating room. “I believe you need a microscopic second look to ensure that the vocal cords are healed,” he says. “I’m doing fairly substantial tumors this way.” Patients can safely wait between sittings, he explains, because early vocal-cord cancers don’t metastasize.
There has been substantial demand for the procedure since Zeitel reported on the work in May. “I was contacted by about 125 cancer patients in the last several weeks,” he says. “We’re like an oncological MASH unit.” And he expresses confidence in the value of the new approach. “The pulsed KTP laser is a critical innovation in the instrumentation arsenal of the laryngeal surgeon,” he says. “It has greatly enhanced the precision by which we can perform many procedures for chronic laryngeal diseases, both in the operating room accompanied by the surgical microscope and in the office.” – PG