ORIGINAL ARTICLE |
https://doi.org/10.5005/jp-journals-10003-1387 |
Effect of Smoking on Vocal Fold Polyp: A Comparative Histopathological Study
1,2,5Department of ENT, Christian Medical College, Vellore, Tamil Nadu, India
3Department of Pathology and Lab Medicine, All India Institute of Medical Sciences, Bhopal, Madhya Pradesh, India
4Department of Pathology, Christian Medical College, Vellore, Tamil Nadu, India
Corresponding Author: Roshna Rose Paul, Department of ENT, Christian Medical College, Vellore, Tamil Nadu, India, Phone: +91 9894364895, e-mail: anhsor@gmail.com
How to cite this article: Trupthi MC, Paul RR, Mukhopadhyay S, et al. Effect of Smoking on Vocal Fold Polyp: A Comparative Histopathological Study. Int J Otorhinolaryngol Clin 2021;13(3):95–100.
Source of support: Nil
Conflict of interest: None
ABSTRACT
Vocal fold polyp is a benign condition of the vocal fold, which requires surgical excision under general anesthesia. We intend to look for any early premalignant changes among smokers with vocal polyp as it is a well-known carcinogen.
Aim and objective: To study the (1) impact of smoking on the histopathology of vocal fold polyps and (2) serum IgE levels in patients with vocal cord polyps.
Materials and methods: All patients above 18 years diagnosed with vocal polyp fitting into our inclusion criteria were included in the study. The study group was divided into group A—smokers with vocal polyp and group B—nonsmokers with vocal polyp. Serum IgE levels were assessed in all patients with vocal polyps. All patients underwent microlaryngoscopy and excision biopsy under general anesthesia. The surgical specimen was sent for histopathological examination. The pathologists were blinded to the smoking-related history.
Results: In all, 70 patients diagnosed with vocal polyp were enrolled in the study with a smoker to nonsmoker ratio of 1:1. Voice abuse was seen in 85% of smokers and 74% of nonsmokers. There was an in increase in thickness of the basement membrane and fibrosis of vocal polyp in smokers on histopathological examination. Among the 70 patients we studied, dysplasia was seen in 10% of vocal polyps irrespective of smoking, which was statistically significant (p-value <0.001). Serum IgE was elevated in both smokers and nonsmokers (60%).
Conclusion: Conflicting reports regarding the histopathological examination of vocal fold polyps suggest further multicentric studies. Histopathological evidence of dysplasia in statistically significant numbers in both groups suggests a mandatory early surgical excision.
Keywords: Dysplasia, Microlaryngoscopy, Polyp, Smoking
INTRODUCTION
Vocal fold polyp is a benign vocal cord lesion that affects the voice of a person. They are most commonly unilateral, broad based, sessile or pedunculated, clear, white or reddish, small or large lesions, and are usually located in the anterior or middle third of the vocal fold.1 The most common causative factor for this lesion is phonotrauma. Other contributory factors are irritation from sources like tobacco, alcohol, laryngopharyngeal reflux, and upper respiratory allergies.2
Smoking is known to have several adverse effects on the larynx including change in the quality of voice.3,4 Animal studies have shown that smoking can cause deformation of the mucosa of the vocal fold.5,6 There are studies showing increased association of laryngopharyngeal reflux with smoking.7 Chronic irritation of the larynx caused by smoking leads to abnormal keratin production and its accumulation in vocal fold epithelium.8 It is considered one of the major risk factors for epithelial dysplasia.9 Laryngopharyngeal reflux is also another factor that could contribute to the same.
Change of voice due to vocal polyp is a common pathology seen in the outpatient area of our department. As smoking is still prevalent in our country, most patients with vocal polyp have associated history of smoking. The association of laryngeal epithelial changes though reported has not been reported widely from the Indian subcontinent. This study was thus undertaken to study the effect of smoking on the laryngeal mucosa.
MATERIALS AND METHODS
This prospective observational study was conducted in the Departments of Otorhinolaryngology and Pathology, Christian Medical College (a tertiary academic teaching hospital in Vellore, Tamil Nadu, India) from January 2015 to August 2016, following approval of the Institutional Review Board (IRB MIN No. 9680 dated October 20, 2015).
Participants
All patients with vocal fold polyp who fulfilled the criteria and were scheduled for microlaryngoscopic surgery were enrolled in the study after taking informed consent.
Inclusion Criteria
Patients above 18 years with vocal cord polyps.
Willing to take part in study.
Exclusion Criteria
History of proven head and neck malignancy.
Previous history of head and neck irradiation.
Immunocompromised individuals.
Sample Size Calculation
The sample size was calculated based on a study done by Effat,3 in which the histopathology of vocal polyps of smokers vs nonsmokers was compared. With a prevalence of 82% keratinization in smokers and 43% in nonsmokers, our sample size was calculated to be 56 (28 in each arm). This was calculated with a power of 80% and a significance level of 5%.
Statistical Analysis
The study variables were summarized using descriptive statistical methods. The association between histopathological findings and smoking status were assessed using Chi-squared tests. The association between other baseline variables (age, gender, reflux, duration of smoking, and hoarseness) and histopathological findings were done using independent two sample t-test for continuous and Chi-squared test for categorical variables. All analyses were done using SPSS 11.0.
Methodology
Seventy patients above 18 years of age who were clinically diagnosed (by indirect laryngoscopy) and/or confirmed by flexible nasopharyngolaryngoscopy to have vocal polyp and willing to undergo microlaryngoscopy with excision of the lesion were included in the study. They were screened and clinically evaluated by the principal investigator and categorized into two groups: smokers and nonsmokers. Patients who had stopped smoking 5 years ago or who never smoked were categorized as nonsmokers and the rest were considered smokers. Sociodemographic factors like age, gender, occupation, and level of voice use were documented in the pro forma. The level of voice use was classified as Level 1—elite voice performers (singers, actors); Level 2—professional voice users (teachers, lecturers, lawyers); Level 3—nonvocal professionals (businessmen, doctors, legal advisors); Level 4—nonvocal nonprofessionals (housewives and farmers).
The duration of hoarseness, voice abuse-misuse, number of years of smoking, and the number of cigarettes/beedis smoked per day were also documented.
Data collected were entered in the pro forma. All subjects underwent microlaryngoscopy and excision biopsy under general anesthesia. Two different pathologists who were blinded to the smoking-related history independently assessed all excised surgical specimens.
RESULTS
Seventy patients diagnosed with vocal polyp were enrolled in the study with a smoker to nonsmoker ratio of 1:1. In total, there were 35 smokers and 35 nonsmokers. Various parameters that were looked into were basic sociodemographic features like age, gender, level of voice use and history related to smoking, voice abuse, laryngopharyngeal reflux (LPR), and upper respiratory allergy. Histopathological examination of all the vocal polyps was done to look for changes in the epithelium, basement membrane, and lamina propria, comparing between smoker and nonsmoker group.
Age Distribution
The study participants age ranged 24–67 years with a mean age of 43 years. In both the study groups, majority were aged less than 45 years. Among 35 smokers in the study, 18 (51.4%) and among nonsmokers, 21 (60%) were aged less than 45 years as shown in Table 1.
| Age (years) | Smokers, n (%) | Nonsmokers, n (%) |
|---|---|---|
| <45 | 18 (51.43) | 21 (60) |
| 45–59 | 17 (48.57) | 11 (31.43) |
| 60 and above | 0 (0) | 3 (8.57) |
| Total | 35 (100) | 35 (100) |
Gender Distribution in the Study Population
All the 35 study participants in the smoker group were men. In the nonsmoker group, 10 (28.6%) were women and 25 were men as shown in Table 1. Combining both the groups, vocal polyp was more common in men (85.71%) as shown in Figure 1.
Fig. 1: Gender distribution of vocal cord polyp patients with and without history of tobacco use in smoke form
History of Voice Use/Abuse
There was history of voice abuse in a majority of the participants. In all 30 out of 35 (85%) smokers and 26 out of 35 (74%) nonsmokers gave history of voice abuse as shown in Table 2.
| Characteristic | Smokers (N = 35), n (%) | Nonsmokers (N = 35), n (%) |
|---|---|---|
| History of voice overuse | ||
| Yes | 30 (85.71) | 26 (74.29) |
| No | 5 (14.29) | 9 (25.71) |
In our study, there is a predominance of Level 3 voice users among the smoker group (42%) and Level 4 among the nonsmoker group 40%. Of the smokers with vocal polyps, 34% were Level 2 voice users and 22% were Level 4 whereas among nonsmokers 37% were Level 3 and 20% were Level 2 voice users as shown in Figure 2.
Figs 2A and B: Level of voice use among smoker and nonsmoker patients with vocal polyp
Serum IgE Levels
In our study, 60% had raised serum IgE level. It is interesting to note that the incidence of serum IgE elevation is 60% in both smokers and nonsmokers as shown in Table 3.
| IgE levels | Smokers (n = 35) | Nonsmokers (n = 35) | Test value | p value |
|---|---|---|---|---|
| Median (IQR) | 224.8 (70.1–730.8) | 146.7 (38.3–380.2) | 0.887 | 0.375 |
| Categories | ||||
| Raised IgE levels (>100) | 21 (60) | 21 (60) | 0.000 | 1.000 |
| Normal | 14 (40) | 14 (40) |
Histopathological Features
Specific epithelial changes like hyperkeratosis, parakeratosis, hyperplasia, atrophy, and dysplasia were carefully looked for in all the specimens. There was no apparent difference in the epithelial histology among the two groups and the results were as seen in Table 4 and Figures 3 and 4.
| Histopathological observation | Smokers (N = 35), n (%) | Nonsmokers (N = 35), n (%) | Chi-square value | p value |
|---|---|---|---|---|
| Hyperkeratosis | ||||
| Present | 35 (100) | 34 (97.1) | 1.014 | 0.314 |
| Absent | 0 | 1 (2.9) | ||
| Parakeratosis | ||||
| Present | 35 (100) | 33 (94.3) | 2.06 | 0.151 |
| Absent | 0 | 2 (5.7) | ||
| Hyperplasia | ||||
| Present | 23 (65.7) | 18 (51.4) | 1.471 | 0.225 |
| Absent | 12 (34.3) | 17 (48.6) | ||
| Dysplasia | ||||
| Present | 3 (8.6) | 4 (11.4) | 0.158 | 0.690 |
| Absent | 32 (91.4) | 31 (88.6) | ||
| Atypia | ||||
| Present | 4 (11.4) | 7 (20) | 0.970 | 0.324 |
| Absent | 31 (88.6) | 28 (80) | ||
| Atrophy | ||||
| Present | 12 (34.3) | 18 (51.4) | 2.100 | 0.147 |
| Absent | 23 (65.7) | 17 (48.6) | ||
| Ulceration | ||||
| Present | 4 (11.4) | 5 (14.3) | 0.128 | 0.721 |
| Absent | 31 (88.6) | 30 (85.7) | ||
| Microorganism | ||||
| Present | 3 (8.6) | 1 (2.9) | 1.060 | 0.303 |
| Absent | 32 (11.4) | 34 (97.1) |
Fig. 3: Hyperkeratosis
Fig. 4: Dysplasia
Thickness of the basement membrane was noted to be slightly higher in smokers (68.6%) than nonsmokers (57%) as shown in Table 5 and Figure 5.
| Histological observation | Smokers (n = 35), n (%) | Nonsmokers (N = 35), n (%) | Chi-square value | p value |
|---|---|---|---|---|
| Focal thickness | 14 (40) | 14 (40) | 1.615 | 0.446 |
| Diffuse thickness | 10 (28.6) | 6 (17.1) | ||
| Thin | 11 (31.4) | 15 (42.9) |
Fig. 5: Basement membrane thickness
In the lamina propria, fibrosis was seen to be greater among smokers (45.71%) as compared to nonsmokers (28.57%). Other histopathological changes like edema, vascularity, and hyalinization were seen to have a similar incidence in both groups, as shown in Table 6 and Figure 6.
| Histological observation | Smokers (N = 35), n (%) | Nonsmokers (N = 35), n (%) | Chi-square value | p value |
|---|---|---|---|---|
| Edema | ||||
| Present | 31 (88.57) | 30 (85.71) | 0.1275 | 0.721 |
| Absent | 4 (11.43) | 5 (14.29) | ||
| Fibrosis | ||||
| Present | 16 (45.71) | 10 (28.57) | 2.2028 | 0.138 |
| Absent | 19 (54.29) | 25 (71.43) | ||
| Vascularity | ||||
| Present | 32 (91.43) | 32 (91.43) | 0.0000 | 1.000 |
| Absent | 3 (8.57) | 3 (8.57) | ||
| Hyalinization | ||||
| Present | 30 (85.71) | 30 (85.71) | 0.0000 | 1.000 |
| Absent | 5 (14.29) | 5 (14.29) | ||
| Extravasated red blood cells | ||||
| Present | 28 (80) | 31 (88.57) | 0.9707 | 0.324 |
| Absent | 7 (20) | 4 (11.43) | ||
| Hemosiderophages | ||||
| Present | 18 (51.43) | 16 (45.71) | 0.2288 | 0.632 |
| Absent | 17 (48.57) | 19 (54.29) |
Fig. 6: Hyalinization and vascularity
DISCUSSION
This prospective observational comparative study was conducted in a tertiary care hospital to explore differences in clinical and histopathological presentation of vocal polyp among smokers and nonsmokers. There were 70 patients, 35 each in smoker and nonsmoker groups. In our study, vocal polyps were exclusively seen in adults as in other studies8 with the mean age of 43 years and age ranging from 24 to 67 years. Though among the smokers there were almost equal number of patients in the middle and older age group, among the nonsmokers 60% were in the middle age group (<45 years).
Voice overuse was seen in most of our patients: 85% of smokers and 74% of nonsmokers, which suggests that voice overuse is a strong etiological factor for vocal cord polyp.
In our study, considering the level of voice users, it was noted that among the smokers, the majority of the affected were Level 4 (nonvocal nonprofessional like clerks/mechanics) whereas among the nonsmokers the majority were Level 3 (nonvocal professional like businesspersons/legal advisors). An association of vocal polyp with smoking in nonvocal nonprofessional voice users (Level 4) has not been previously reported. It may be worthwhile to do further studies to check whether an actively phonating larynx has less adverse affect of smoking.
Though IgE levels have been reported to be higher among those who smoke as reported by Dong et al.,10 our study noted raised serum IgE levels in 60% of both the groups. This suggests that allergy is a constant contributory etiology, irrespective of smoking and the latter should be considered an additional risk factor to allergy. This warrants further research into association of allergy and smoking in vocal cord polyp as there is no previous literature regarding this issue.
On comparing the epithelial morphology, Effat et al.3 had reported a markedly higher proportion of hyperkeratosis, dysplasia, and atypia in smokers. In contrast, our study revealed an almost equal proportion in both groups. We also noted that atypia and dysplasia were in higher proportion in nonsmokers though not statistically significant. This was different from Effat et al.,3 who reported a significant increase in atypia and dysplasia in smokers. This may be due to the difference in ethnicity as well as environmental exposures. However, the concern is that of the 70 patients we studied, dysplasia was seen in 10% (p-value <0.001) of vocal polyps irrespective of smoking. Multicenter studies with larger sample sizes would be needed to overcome these inconsistencies.
Regarding basement membrane morphology, Effat et al.3 reported that vocal polyps had thinner basement membrane in smokers as compared to nonsmokers. In contrast, our study revealed that in the basement membrane, though similar percentage in both groups had presence of focal thickness, diffuse thickness was higher in the smoker group (28.6% vs 17.1%). This increase in thickness of the basement membrane can be attributed to increased fibrosis that occurs secondary to raised Transforming growth Factor beta (TGF-β) levels in smokers.11
On comparing the morphology of lamina propria, Effat et al.3 noted a higher incidence of hyalinization, fibrosis, vascularity, extravasated red blood corpuscles, and edema in the lamina propria of vocal polyps among smokers. In contrast, our study revealed edema, vascularity, hyalinization, extravasation of red blood cells, and hemosiderophages, almost similar in both the groups whereas fibrosis was greater in the smokers (45.71% vs 28.57%). This value was not statistically significant though. Besides, hyalinization was seen in 85% of both smokers and nonsmokers in our study in contrast to Effat et al.’s study in which it was shown to occurred in a majority (82%) of smokers.7 This may be due to the differential exposure to environmental factors and racial differences between the two study populations.
LIMITATIONS
Though we attained the sample size needed for the study, a larger group may have revealed statistically significant associations of confounding factors between the groups.
History of passive smoking was not taken into consideration.
CONCLUSION
Smoking is an additional confounding risk factor along with allergy associated with vocal polyp.
Conflicting reports regarding smoking and the histopathological examination of vocal fold polyps suggests further multicentric studies.
The association of vocal polyp with smoking in nonvocal nonprofessional voice users (Level 4), which has not been previously reported may suggest that the adverse effect of smoking could be more on a relatively less phonatory larynx.
Histopathological evidence of 10% dysplasia, which is statistically significant in these patients irrespective of smoking, suggests a mandatory early microlaryngeal surgical excision and histopathological examination.
ACKNOWLEDGMENTS
Authors would like to acknowledge our statistician Mr Prasanna, Department of Biostatistics, CMC Vellore for helping with the data analysis.
REFERENCES
1. Rubin JS, Yanagisawa E. Benign vocal fold pathology through the eyes of the laryngologist. In: Rubin JS, Sataloff RT, Korovin GS, Editors, Diagnosis and treatment of voice disorders, 3rd edition, 2006; San Diego, CA: Plural Publishing Inc. p. 73–90.
2. Martins RHG, Defaveri J, Domingues MAC, et al. Vocal polyps: clinical, morphological, and immunohistochemical aspects. J Voice 2011;25(1):98–106. DOI: 10.1016/j.jvoice.2009.05.002.
3. Effat KG, Milad M. A comparative histopathological study of vocal fold polyps in smokers vs nonsmokers. J Laryngol Otol 2015;129(5) 484–488. DOI: 10.1017/S002221511500064X.
4. Gonzalez J, Carpi A. Early effects of smoking on the voice: a multidimensional study. Med Sci Monit Int Med J Exp Clin Res 2004;10(12):CR649-CR656. PMID: 15567981.
5. Duarte JL, de Faria FAC, Ceolin DS, et al. Effects of passive smoke inhalation on the vocal cords of rats. Braz J Otorhinolaryngol 2006;72(2):210–216. DOI: 10.1016/s1808-8694(15)30057-4.
6. Işik ACU, Kalender Y, Yardimci S, et al. Environmental tobacco smoke in rats. J Otolaryngol 2004;33(6):382–386. PMID: 15971655.
7. Smit CF, Copper MP, van Leeuwen JA, et al. Effect of cigarette smoking on gastropharyngeal and gastroesophageal reflux. Ann Otol Rhinol Laryngol 2001; 110(2):190–193. DOI: 10.1177/000348940111000216.
8. Ma L-J, Wang J, Xiao Y, et al. Clinical classification and treatment of leukokeratosis of the vocal cords. Chin Med J (Engl) 2013;126(18): 3523–3527.
9. Sadri M, McMahon J, Parker A. Laryngeal dysplasia: aetiology and molecular biology. J Laryngol Otol 2006;120(3):170–177. DOI: 10.1017/S0022215105005360.
10. Dong J-J, Shen JJ, Lee Y-J. Dose-dependent effect of cotinine-verified tobacco smoking on serum immunoglobulin E levels in Korean adult males. Nicotine Tob Res 2019; 21(6):813-817. DOI: 10.1093/ntr/ntx247.
11. Takizawa H, Tanaka M, Takami K, et al. Increased expression of transforming growth factor-β1 in small airway epithelium from tobacco smokers and patients with chronic obstructive pulmonary disease (COPD). Am J Respir Crit Care Med 200;163(6):1476–1483. DOI: 10.1152/ajplung.2000.278.5.L906.
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