No Difference in Voice Quality After Comparing Different Treatments for Vocal Cord Cancer
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There is no significant difference in voice quality after external beam radiation therapy (EBRT) compared to endoscopic CO2 laser excision (CLE) in T1 glottic cancer. This is the conclusion of meta-analysis assessing voice outcomes after treatment for early glottic cancer.
A diagnosis of T1 glottic cancer, which is a tumor limited to one (T1a) or both (T1b) vocal cords, can at first appear to be devastating to the patient. However, EBRT and CLE have proven to offer high and comparable cure rates for this disease. What has not been determined is what procedure offers the best oncologic cure while minimizing adverse effects on the patient voice.
Problems associated with study design and data collection have resulted in varying voice outcomes in studies exploring CLE or EBRT. Essentially, perceptual analysis of vocal outcomes following treatment of T1 glottic cancer shows contradictory results. Both improved voice quality with EBRT and similar outcomes regardless of type of treatment have been found. Acoustic voice parameters have also demonstrated inconsistent voice outcomes following EBRT and CLE. Variability in the mouth to microphone distance, recording equipment, analyzing software, and patient effort may explain the disparate results.
As opposed to these imperfect quantitative analysis techniques, patient-based outcomes assessments may be more pertinent to patient choice of treatment. Recent reports have utilized the Voice Handicap Index (VHI), a validated instrument that measures patients’ disability from voice disorders, to assess treatment outcomes for EBRT versus CLE in T1 glottic cancer. Two reports demonstrate favorable VHI scores in CLE treated patients. However, patients treated with CLE included those with carcinoma in situ (CIS) and invasive T1 lesions. Because patients with CIS would require less invasive surgery, their voice results may be better than those requiring more involved resections, biasing the results in favor of CLE. Hence, further exploration and clarification of the voice outcomes from T1 glottic cancer treatment is needed.
To test the hypothesis that endoscopic resection produces comparable levels of voice handicap as EBRT, a meta-analysis of the literature regarding VHI measurement post-treatment for T1 glottic cancer, excluding CIS, was performed. The authors of “Voice-Related Quality of Life in T1 Glottic Cancer: Radiation versus Endoscopic Excision,” are Seth M. Cohen, MD, MPH, C. Gaelyn Garrett MD, William D. Dupont PhD, Robert H. Ossoff, DMD MD, all affiliated with Vanderbilt University, Nashville, TN; and Mark S. Courey MD, with the University of California-San Francisco Voice Center, San Francisco, CA. Their findings will be presented at the 127th Annual Meeting of the American Laryngological Association, Chicago, IL, May 19-20, 2006.
Methodology: A meta-analysis of the current literature regarding voice-related quality of life (QOL) and treatment for T1 glottic cancer was undertaken. As the most commonly used patient self-report instrument, the VHI was chosen as the main outcome variable. The VHI ranges from 0 to 120 with a lower score signifying fewer handicaps. The search was conducted between November 1, 2004 and March 31, 2005. Attempts to retrieve studies published between January 1, 1966 and March 31, 2005 were made. A computerized search for the following key words alone or in combination was undertaken: voice handicap index, glottic cancer, laryngeal cancer, voice quality, treatment outcome, voice outcome, quality of life, and questionnaires. All abstracts were reviewed and potential articles assessed for inclusion criteria. Bibliographies were reviewed to search for any additional articles.
Articles published in English that measured the VHI at least three months following either EBRT or endoscopic resection for T1 glottic cancer were selected. Because no articles assessing the VHI following cold excision for T1 glottic cancer were identified, the endoscopic resection group consisted of only cases employing the CO2 laser. Articles for which either a mean or median value or a measure of variability of the VHI were unavailable and with duplicate data were excluded.
Results: Six studies encompassing 208 patients (6T1b and 202 T1a) treated with CO2 laser excision and 91 (6T1b and 85 T1a) with external beam radiation therapy were identified. The post-treatment voice handicap index scores from each study were obtained allowing overall group (CO2 excision vs Xrt) mean VHI scores with 95 percent confidence intervals to be calculated. Comparing the group mean VHI scores demonstrated no difference in the post-CO2 vs post-Xrt treatment groups, signifying comparable levels of voice handicap after treatment of T1 glottic cancer by each method.
Conclusion: For T1a glottic cancer, patients perceive similar, low levels of voice handicap whether treated by EBRT or CLE. This may facilitate patient counseling about appropriate treatment selection. Further study is needed to clarify voice outcomes in T1b and anterior commissure lesions and to provide further insights about how the extent of surgical resection, potential reconstruction, and surgical and radiation techniques impact voice handicap. Post-treatment voice therapy and potential professional voice use may also influence voice outcomes and requires more investigation.
American Laryngological Association
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