ORLANDO, FL-Laser involution of early stage glottic cancer-with complete treatment of the malignancy weeks after the first session-appears to offer long-term control of the disease while preserving excellent voice function, researchers reported at the 88th annual meeting of the American Broncho-Esophagological Association (ABEA).
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June 2008
In a preliminary report that described treatment of 23 patients, Steven M. Zeitels, MD, Eugene B. Casey Professor of Laryngeal Surgery at Harvard Medical School in Boston, suggested that treatment with pulsed angiolytic lasers might offer a better solution for laryngeal cancer than ionizing radiation.
This is somewhat unconventional, Dr. Zeitels said during the ABEA session, which was conducted as part of the annual Combined Otolaryngology Spring Meeting. I’ll ask you to keep an open mind.
He said the use of pulsed angiolytic lasers has previously been demonstrated to be effective for managing vocal fold dysplasia.
Based on this experience, we evaluated treating early glottic cancers by selectively targeting the intralesional microcirculation, Dr. Zeitels said. Initially we used the yellow-light 585-nm pulsed-dye laser, but ultimately abandoned it. For the past three years, the 532-nm pulsed-KTP [potassium titanyl phosphate] laser was used exclusively because it provides substantially enhanced precision, as well as being less expensive. This approach was derived from the work of the late Judah Folkman’s concepts of neoplastic growth resulting from tumor angiogenesis.
Staged microlaryngeal treatment was adopted because it facilitated optimal functional results and was considered safe because early glottic cancer rarely metastasizes. Furthermore, intercurrent disease for around three months is typical when treating these tumors with radiotherapy, he said.
Dr. Zeitels also noted that the initial angiolytic laser endoscopic management of glottic cancer with lasers still preserves other treatment options including other forms of surgery and radiation.
Study Results
Among the 23 patients, 13 had cancer in both vocal folds; 13 presented with T1 disease, nine had T2 disease, and one had T4 disease. Dr. Zeitels said that among these patients one recurrence was observed, but retreatment with the laser involuted the tumor and that patient has now been subsequently free of disease for more than two years.
All the patients have no evidence of disease, and 13 of them had treatment more than two years ago. The mean follow-up was 28 months. The longest a patient has cancer-free subsequent to the laser treatment has been 5.5 years, Dr. Zeitels said in his oral presentation.
Dr. Zeitels used the 585-nm pulsed-dye laser in the initial eight patients and the 532-nm pulsed-KTP laser in the last 15 patients to eradicate the vocal fold tumors. Both lasers are capable of involuting vocal fold cancer; however, we observed the pulsed-KTP laser to be more effective, he said. Incremental endolarygneal treatment of early glottic cancer is safe and allows for substantially better functional outcome.
This approach is conceptually attractive since it is repeatable, preserves all conventional cancer treatment options, and results in outstanding vocal function by improving phonatory mucosal pliability, he said.
Dr. Zeitels explained that although the KTP can be used in a continuous mode to imprecisely cut and ablate tissue, this is not what we did. By precisely calibrating settings including the pulse width of the KTP laser, we ablated the tumor without substantially heating and scarring the underlying residual normal vocal tissue.
Further Testing Necessary
Preliminary observations suggest that this new and novel cancer treatment strategy is effective; however, larger patient cohorts and longer follow-up will be necessary to establish incontrovertible oncological efficacy, Dr. Zeitels said.
Amy Chen, MD, MPH, Associate Professor of Otolaryngology at Emory University in Atlanta, concurred. There is no study that includes just 23 patients that would make a procedure ready for prime time, said Dr. Chen, who also serves as Director of Health Services Research for the Atlanta-based American Cancer Society.
Dr. Chen noted that radiation therapy, although highly effective and widely used, is expensive and time-consuming. A course of radiotherapy can cost tens of thousands of dollars, she said. It usually involves 35 treatments with patients coming to the radiation suite daily for at least six weeks. (The laser treatment required only two or three sessions.)
She noted that such a regimen can be grueling for the patient, especially a patient who lives a distance from the tertiary hospital where the treatment is offered. Many patients have to take time off from work, and that can compromise their employment.
Dr. Chen said that ionizing radiation therapy raises the threat of future malignancies and can cause long-term and permanent hypothyroidism, requiring lifelong medication.
It would be helpful to find some treatment that does not cause the adverse effects. That is why this study is fascinating and may be promising, she said.
Criteria for Success
Because glottic cancer is relatively rare and treatments that are now employed are generally acceptable, Dr. Chen said that a head-to-head comparison would probably require a comparison of subjective and objective voice outcomes.
According to the American Cancer Society, an estimated 10,000 new cases of laryngeal carcinoma are diagnosed each year in the United States. About 3900 deaths occur yearly as a result of this disease. Laryngeal cancer affects men four times more frequently than women. Laryngeal cancer makes up 1% to 2% of all malignancies worldwide.
Dr. Zeitels said that in his preliminary study, what we are seeing is that the voice data is the best we ever had, especially for those patients with bilateral disease. Objective voice measures revealed overall improvements in the postsurgical group. These results substantiated stroboscopic findings of enhanced mucosal wave function and vocal fold vibration.
We created a hybrid technique employing microsurgically directed nonionizing radiation. Incremental treatment of the glottis is much like treating sun-damaged skin in that you are trying to optimize the form and function. You are essentially reducing mid-sized tumors into smaller ones or complete involution and going back after six weeks to confirm resolution or treat residual limited disease. As necessary with bilateral disease in the anterior commissure, we intentionally leave a little tumor anteriorly on one vocal fold to avoid a synechia and web, since we know we are coming back in six weeks to finish the job.
Dr. Zeitels disclosed possible conflicts of interest with Laserscope Inc., Pentax Inc., and Endocraft LLC. His work also received funding from the nonprofit Eugene B. Casey Foundation and the Institute of Laryngology and Voice Restoration. We have not received any financial remuneration from any laser company, he said. We have received lasers.
©2008 The Triological Society