Abstract

Laryngeal carcinoma forms about 1-2% of all the cancers.  It is usually known as a male disease.  Although its rate is increasing in women in Western countries, it is still more common in men in our country.  Several etiologic factors have been mentioned for this cancer among which the most important is smoking and alcohol abuse.  There are some evidences regarding the impact of occupational and dietary factors in occurrence of the disease. The most important of these factors are exposure to chemicals and heavy metals, working in leather and textile industries, and vitamin A and C deficiency.  This study is an epidemiologic study using the patient's files who has been admitted in ENT department of Imam Khomeiny Hospital during the period of 1986 to 1994. This is a descriptive study and the data collection has been retrospective.  Our study showed that due to cultural and religious characteristics of our society male to female ratio of laryngeal carcinoma is still at least 10/1 in our country.  In spite of significant decrease in alcohol consumption, opium abuse is still high in some areas of our country and is considered as one of the predisposing factors at present time.  The other different finding in this study is a higher incident of trans-glottic tumor which is due to late referral of the patients and progression of the disease at time of diagnosis.  Age wise there isn't any significant difference between this study and the previous ones. 

Having the results of this study regarding the effect of above factors in incidence of laryngeal carcinoma the main objective of this paper is to re-emphasis on the importance of preventing measures including restrictive control on opium abuse, and limitation of exposure to carcinogenic materials.  Also performing screening methods on high risk population for early diagnosis of the disease is recommended.

Key words: Larynx, Cancer, Epidemiology, Squamous cell carcinoma.

Introduction

Cancer of larynx forms about 1-2% of all the cancers.  Larynx is the second most site for upper respiratory and upper gastrointestinal tract cancer after oral cavity.  Squamous Cell Carcinoma makes 95% of Laryngeal carcinomas.  Every year 12500 mew cases are diagnosed in US and 4000 patient die from this disease (1).

Several epidemiologic studies have shown a strong relationship between tobacco smoking and alcohol consumption and laryngeal carcinoma.  These studies have proved the adverse effect of each of these factors individually on laryngeal mucosa and also have showed their synergistic effect in laryngeal carcinoma formation (2).  Occupational and dietary factors have also been proved to have some relationship with the disease.

The most common age for the disease is sixth and seventh decades of life (4).  Less than 1% occur before age of 30 except for the supra glottic type that has a lower age range (2). 

In terms of pathologic type to the tumor, 88-98% of the laryngeal carcinoma is SCC.  Laryngeal carcinoma is supraglottic in 40%, glottic in 59% and subglottic in 1% of           the cases (6). Male to female ratio is 6.2/1 in glottic type and less than 3.5/1 in supraglottic type, which shows higher risk of supraglottic cancer for women.  Malnutrition and vitamin deficiency is a proven risk factor for laryngeal carcinoma (3) although the carcinogen is still unknown.  Graham and his co-workers compared a group of 338 white men suffering from laryngeal carcinoma with a control of 359 people who were a documentable dietary routine.  This study showed that in cases whose dietary intake of vitamin A and C has been less than 1/3 of their daily need, the incident of laryngeal carcinoma increased by 3 times comparing to those whose intake of above vitamins was more than their need.  This rate had obtained after omitting the other risk factors like cigarette smoking and alcohol abuse (3).

The other risk factor for laryngeal carcinoma is gastro esophageal reflux disease.  In one study this factor has had a more obvious effect on the incidence of carcinoma of anterior 2/3 of the glottis.

Exposure to some chemical materials and some occupations will cause an increase in the incidence of laryngeal carcinoma (4,9); this increase is not explainable with smoking and alcohol alone.  Workers of fabric and leather industries and those who are exposed constantly to dust especially road workers and heavy or light metal industry workers show a higher incidence rate for laryngeal carcinoma.  This incidence is twice for people who are exposed to asbestos, silicon and fabric material comparing to control population (4).  In other studies it has been proven that mine workers, and those work for cement, chemical, plastic and biochemical industries and are exposed to chemicals like sulfuric acid, sulfur, nickel and beryllium are at higher risk for laryngeal carcinoma (6).

The effect of some other factors like a mutagen of human papilloma virus need more study (10).

Method

This is a retrospective study using the patient's files who were admitted in ENT department of Imam Khomeiny Hospital, with the diagnosis of laryngeal carcinoma, between 1986 and 1994.   About 150 files were studied from which many had to be excluded from the study due to incomplete information.  100 files which were more informative were chosen, information regarding age, sex, occupation, place of residence, chief complaint, history of cigarette or other types of tobacco smoking, alcohol consumption, site of the tumor and the pathology result were retrieved and  analysed consequently. The study is descriptive and the screening criterion was the pathology report in favor of laryngeal carcinoma.

Findings and discussion

As it is shown in Table 1, most of the patients were in their sixth or seventh life decades (46 and 25 cases respectively).  This is similar to the results of studies from other countries (1).

Table 1: Age frequency of laryngeal carcinoma in 100 studied cases in Imam Khomeiny Hospital, 1986-1994.

 In terms of male to female ratio almost all of the cases in this study were men.  There were a few female cases from original screening which were proved to be laryngopharyngeal carcinoma cases in which the tumor originated from pharynx.  These were therefore omitted from the study. According to results of studies in western countries the male to female ratio is decreasing.  So it seems that this ratio in our country still very high which could be due to cultural and religious factors which cause a difference in occupations and habits of men and women. 

According to Table 2, 32% of the patients were from in West of Iran, 23% from North, 23% from Central area, 14% from the South and 8%from the East.

Table 2: Area distribution of Laryngeal Carcinoma in 100 patients admitted in Imam Khomeiny Hospital.

The main risk factors according to our study were cigarette smoking and alcohol which is the similar to other studies.  The other risk factor that we considered was opium abuse which hasn't been noted so much in other studies.  In Table 3 we can see that 83% of the patients have been smokers who had smoked 1-2 packs daily for 17 -30 years.  5% were cigarette and alcohol users and 7% were cigarette and opium addicts.  Only 5 patients (5%) didn't use any tobacco or alcohol.  The result of another study showed that only 4% of patients with laryngeal carcinoma aren't smokers (4).  According to studies from other countries 88-99% of laryngeal carcinoma cases are cigarette smokers (12).

Table 3: Risk factors in 100 patients with laryngeal carcinoma admitted in Imam Khomeiny Hospital, 1986-1994.

In terms of chief complaint, 62% change of voice, 34% respiratory distress, 3% pain in laryngeal area and 1% tumor invasion to skin was reported in our cases.  There were some other sign and symptom detected at the time of referral but our emphasis has been on chief complaint.

The other difference between our study and those of other countries was the extension and progression of the tumor at the time of diagnosis, to some extent that the original site of the tumor hasn't been detectable.  In the results of other studies from around the world the most common site has been reported to be glottis or supra glottis (6).

In our patients tumor was limited to glottis in 14%, and supra glottis in 60% of the cases.  In the rest of the cases tumor had progressed to the whole area of glottis and supra glottis.  The possible reason for this high rate of trans-glottal cases is late referral and lack of an organized check-up system.

In terms of pathology of the tumor, 78% of the cases were SCC, 7% verroucos carcinoma, one case of chondrosarcoma and for the rest there wasn't a clear diagnosis. (Table 4).  According to the results of other studies 95-98% of all laryngeal carcinomas are SCC (1).

Table 4:  Pathology results in 100 patients of laryngeal carcinoma admitted in Imam Khomeiny Hospital, 1986-1994.

The best prevention and treatment strategy for carcinoma of larynx is to recognize the risk factors and carcinogens in our environment in order to avoid them as much as possible.  Considering the major risk factors which are cigarette smoking and alcohol abuse,  and the other risk factors like occupation and vitamin A and C deficiency, it seems that the best way to control the illness is to avoid the risk factors.  Therefore our first recommendation is to avoid cigarette and alcohol. 

The other important point noted in this study is the progression of the tumor at the time of referral and the late diagnosis of the disease which has an negative effect on treatment results.  It can improve by educating people, especially those at higher risk, about the first sign and symptoms of the disease, so that they could notice it on time and refer to a doctor for check up.  The physician in turn should perform a careful examination and evaluation using suitable tools and extra work ups in order to make an early diagnosis and suitable and effective treatment.

References:

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Published in Teb-o- Tazkieh Magazine, no. 27. 1997.
By: Ebrahim Razmpa, MD.