Introduction
Transoral laser cordectomy (TLC) and radiotherapy are both considered highly effective treatment modalities for patients with precancerous lesions of the vocal cords and early glottic cancer [
1,
2]. Both methods provide excellent disease-free intervals, overall survival, and larynx preservation for T1–T2 carcinoma [
3‐
6]. However, TLC offers several advantages over radiotherapy, such as one-session therapy, short hospitalization, reduced morbidity, and high cost-effectiveness [
2,
3,
7]. In addition to survival, voice outcomes are important for posttreatment quality of life; therefore, starting from the time TLC was introduced, voice outcomes have been frequently discussed [
8]. According to several studies, long-term voice outcomes (6–24 months) have been excellent after a subepithelial or subligamental cordectomy, but after more extended surgeries, voice outcomes remain poor, similar to preoperative tumor-associated dysphonia [
4,
8‐
10]. Based on those findings, TLC is currently recommended, even for voice professionals (e.g., singers, sports casters, public speakers etc.), when a subepithelial or subligamental cordectomy is planned.
To date, the time period for voice recovery after TLC has not been examined. It is highly important for voice professionals to know when their voice will return. Therefore, the present study aimed to evaluate the development of voice quality after an endoscopic cordectomy for precancerous lesions or early glottic cancer, during the early postoperative period, and to assess differences in voice pattern evolution with different extents of surgery.
Discussion
TLC and radiation therapy are the main treatment modalities for patients with early glottic cancer (Tis, T1–T2). Success is most frequently measured in terms of the local control rate, laryngeal preservation, or in the long term, overall and disease-free survival [
3,
9,
14‐
18]. Endoscopic laser microsurgery costs significantly less than external beam radiotherapy; therefore, microsurgery has been advocated for the treatment of early glottic carcinomas, particularly T1a carcinoma [
3,
7,
16,
19]. Nevertheless, radiotherapy is often considered the treatment of choice, due to the superior voice quality results [
20], despite the comparable cure, similar larynx preservation rates, and lower cost of transoral laser microsurgery. Indisputably, aggravated voice quality significantly affects quality of life, particularly for voice professionals, which currently includes a wide range of professions.
Previous studies that compared transoral excisions and radiotherapy reported equivalent [
2,
14,
21,
22] or better voice quality results with radiotherapy [
23,
24]. However, a later study found that the superiority claim resulted from the heterogeneity of surgical procedures for T1 vocal cord cancer, and that different extents of cordectomy might be necessary for a single TNM classification. Therefore, it was suggested that it might be more reasonable to rate voice outcomes according to the extent of cordectomy, rather than the TNM classification [
25,
26].
A typical example of voice outcome assessments, according to the TNM classification, rather than the extent of cordectomy, was the first randomized controlled trial conducted by Aaltonen et al., in 1998–2008 [
27]. They compared voice results between TLC and radiation therapy at 2 years after the treatments for T1a vocal cord cancer. They found that breathiness and asthenia were significantly worse in patients after TLC than after radiotherapy. However, the overall voice quality did not differ significantly between groups at 2 years after treatment. Nevertheless, although the self-reported voice quality did not differ between groups, hoarseness had less of an impact on daily living activities for patients in the radiation group than for patients in the TLC group. When interpreting the results of that study, it is important to note that those authors did not report the exact extent of the surgical procedures; in particular, they did not specify the types of cordectomy performed. They only stated, that “tumor tissue was removed down to a macroscopically healthy muscle layer.” Therefore, it is likely that the transmuscular type of cordectomy was performed in that study. In that case, the results of the study should not be taken as representative of T1a cancers treated with a subepithelial or subligamental cordectomy. Same approach to evaluate voice after cordectomies was utilized by other authors [
7,
14,
24].
Fink et al. chose a different approach to assessing voice outcomes in their retrospective study [
25]. Those authors analyzed voice results in patients that underwent an ELS Type I, II, or III cordectomy. They determined that the Voice Handicap Index (VHI) improved or showed a trend of improvement postoperatively, and a perceptual analysis did not reveal any significant deterioration in voice quality. The shortcomings of that study were that the exact time point of the postoperative examination was not stated, and the voice parameters were ascertained retrospectively. The VHI was assessed between 1 and 12 months after surgery (median 7 months), and the perceptual analysis was performed between 1 and 3 months after surgery (median 1.9 months). Therefore, it was not possible to trace the evolution of voice quality during the postoperative period.
Currently, most surgeons agree that measuring the extent of cordectomy is crucial in evaluating voice outcomes after a TLC [
10,
25,
26,
28]. We chose this approach in the present study. We divided the patients into two groups, according to the extent of cordectomy. Group I included unilateral subepithelial or subligamental cordectomies (ELS I and II cordectomies), and Group II included unilateral transmuscular, total, or extended cordectomies (ELS III, IV, and V resections). In addition to comparing the static differences between the groups, we compared the evolution of voice quality between groups, during the 6-week and 6-month periods post-surgery. Indeed, no previous study has published information about short-term voice quality after different extents of cordectomy. This information is important for voice professionals and for counselling patients about their plans to return to work.
Our 6-month data were consistent with data reported by Roh et al., who evaluated voice quality at 1 year after a TLC for T1 vocal cord cancer. Those authors reported considerable differences in both the subjective and objective voice outcomes that depended on the extent of surgery. ELS types I and II cordectomies led to significant voice improvements, but more advanced resections led to significantly worse voice outcomes that markedly influenced the quality of life and social activities [
9]. Likewise, Peretti et al. showed significant voice improvements after ELS types I and II cordectomies; in those cases, the voice attained nearly normal parameters. On the other hand, after ELS types III, IV, and V cordectomies, the vocal outcomes at 6 months after surgery were not significantly different from the preoperative voice quality. Therefore, those authors concluded that ELS type I and II resections, when indicated, were adequate procedures, even for voice professionals [
10]. Nevertheless, those studies only reported results after 6 or 12 months post-surgery, respectively.
The present study provided additional information about the post-surgical evolution of voice quality over a short time period in both groups. We found that, at 6 weeks after an ELS I or II cordectomy (Group I), G and R items remained without improvement; however, improved substantially between 6 weeks and 6 months after surgery. Thus, we could conclude that voice professionals would be not able to return to work for at least 6 weeks after those types of surgery. Furthermore, improvements in the voice above preoperative levels could be expected between 3 and 6 months after surgery. We also found that the other parameters did not significantly change postoperatively, in Group I. In contrast, in Group II, the G, R, and B were significantly worse at 6 weeks after surgery, and the voice did not improve even at 6-month-follow-up. Additionally, the MPT in Group II worsened significantly between the preoperative examination and 6 weeks after surgery, and it remained significantly worse than the preoperative level, even after 6 months. Jitter and shimmer were also significantly worse than the preoperative levels at 6 weeks after surgery; however, at 6 months after surgery, they were not significantly worse than the preoperative (tumor associated) level. Therefore, we concluded that after an ELS III, IV, or V cordectomy, the voice would not improve and might even become worse. Therefore, radiotherapy might be preferable for patients that consider voice quality crucial.
This issue was studied with a different methodology by van Loon et al. Those authors presented long-term voice outcomes for patients treated for extended T1 and limited T2 glottic carcinoma. Their patients underwent unilateral transmuscular (ELS type III) or bilateral subligamental (ELS type II) resections. The results of that study suggested that the majority of patients could expect to have mild to very moderate dysphonia 1 year postoperatively, based on ratings by experienced listeners and patient self-assessments [
28].
Patients with severe dysphonia that previously underwent a total or extended cordectomy (ELS types IV and V resections) could be recommended for laryngeal framework surgery, or medialization laryngoplasty. When medialization surgery is considered, it is necessary to allow a prudent lapse of time between the tumor excision and the phonosurgical procedure [
29‐
31]. A minimum 6-month period between the cordectomy and framework surgery is enforced to allow the vocal cord to scar and form a fibrous “neocord”. Then, voice recovery can be evaluated, and the risk of operating on a patient with undiagnosed early recurrence can be avoided [
30]. The reported need for medialization surgery after a total or extended cordectomy was 14.2% [
30]. In the present study, after 6 months, all patients had acceptable voice outcomes for casual communication. Therefore, no patient required laryngeal framework surgery or a medialization laryngoplasty.
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