Disease Overview
It is a malignant tumor originating from the epithelial tissue of larynx mucosa, and the most common type of laryngeal cancer is laryngeal squamous cell carcinoma. It is mostly found in middle-aged and elderly men. The occurrence of this cancer is related to smoking, alcoholism, long-term inhalation of harmful substances and papilloma virus infection. The incidence of laryngeal cancer accounts for about 1-5% of the whole body tumors and ranks third after nasopharyngeal cancer and nasal cavity and sinus cancer in the field of otolaryngology. The age of prevalence is 50-70 years old. It is more common in men than women. It is divided into three different types according to the location of the cancer: (a) supraglottic type (b) glottic type (c) infraglottic type. Stages of laryngeal cancer: stage I, II, III and IV.
The incidence of laryngeal cancer has an increasing trend. The incidence rate of laryngeal cancer in Shanghai was 1.79/100,000 in 1972 and 2.0/100,000 in 1986. The incidence rate of laryngeal cancer in Liaoning Province was 1.5/100,000 in 1986. The incidence rate of laryngeal cancer in Shanghai from 1972 to 1986 changed to +0.21; the statistics of the annual report of the National Cancer Institute published in 1990 in the United States showed that the incidence rate of laryngeal cancer changed to +0.5 from 1973 to 1987. In 1986, the ratio of male to female laryngeal cancer incidence in Shanghai was 6.75:1, and in 1986, the ratio of male to female laryngeal cancer incidence in Liaoning Province was 1.97:1. The proportion of female laryngeal cancer patients in northeast China is higher than that reported at home and abroad. Regardless of gender, laryngeal cancer is most commonly seen at the age of 50-70. The incidence rate of laryngeal cancer is higher in urban than in rural areas, and it is higher in heavy industrial cities with heavy air pollution than in light industrial cities with light pollution.
Etiology
(1) Smoking: Tobacco burning can produce tobacco tar, of which benzopyrene can be carcinogenic and tobacco smoke can cause cilia movement to stop or retard, and also cause mucosal edema and bleeding to thicken epithelial hyperplasia and squamous chemistry as the basis of carcinogenesis
(2) Excessive alcohol consumption: long-term stimulation of the mucosa can cause cancer by denaturing it
(3) Chronic inflammatory stimulation such as chronic laryngitis or inflammation of respiratory tract
(4) Air pollution: long-term inhalation of harmful gases such as sulfur dioxide and productive industrial dusts such as chromium and arsenic can easily cause laryngeal cancer
(5) Virus infection is closely related to cancer generation. It is generally believed that virus can cause abnormal cell division by changing the nature of cells; virus can be attached to the genes and uploaded to the next generation of cells for cancer to occur.
(6) Pre-cancerous lesions: laryngeal keratosis and benign laryngeal tumors such as laryngeal papilloma can become cancerous after repeated attacks
(7) Radiation: treatment of neck swelling with radiation can cause cancer
(8) Sex hormones: experiments have shown that the percentage of estrogen receptor-positive cells in laryngeal cancer patients is significantly higher
Symptoms
According to the location of the cancer, there are the following specific symptoms.
1. Supraglottic type includes carcinomas originating from above the vocal cords, such as epiglottis, aryepiglottic folds, ventricular zone and laryngeal chambers. This type of cancer is less differentiated and develops faster. Due to the rich lymphatic vessels in this area, it is easy to metastasize to the lymph nodes of the deep upper neck group located at the bifurcation of common carotid artery. Later on, when the surface of the cancer is ulcerated, there will be a pharyngeal sensation, which can be reflected to the ear and even affect swallowing. In late stage, when the cancer erodes the blood vessels, there will be blood in the sputum and often foul sputum; when the vocal cords are invaded, there will be hoarseness and difficulty in breathing.
2.Vocal cord type Cancer confined to the vocal cords, more often in the front and middle 1/3, is better differentiated and belongs to grade I and II. It develops slowly and is not easy to metastasize to cervical lymph nodes because of less lymphatic vessels in vocal cords. The main symptom is hoarseness, which gradually worsens. When the tumor enlarges and obstructs the vocal folds, laryngeal wheezing and dyspnea may appear, and in the advanced stage, there is blood sputum and laryngeal obstruction.
3.Inferior vocal cord type The cancer located below the vocal cord and above the lower edge of cricoid cartilage. Because this area is hidden, it is not easy to be detected during routine laryngoscopy. It may be asymptomatic in the early stage, but cough and bloody sputum may occur later. In the late stage, there is often difficulty in breathing because the subglottis area is blocked by the cancer. It may also penetrate the cricothyroid membrane and invade the thyroid gland and prefrontal soft tissue, or infiltrate along the anterior wall of esophagus.
4.Para-vocal type: It refers to the carcinoma originating from the laryngeal ventricle, which is also called trans-vocal carcinoma. This area is very concealed. It can be asymptomatic in the early stage and can easily spread to the lateral paraventricular space. Its clinical characteristics are: hoarseness is the first symptom, often with vocal cord fixation first, and the tumor is not detected. Later, when the cancer expands to the paravocal fold and infiltrates and destroys the laryngeal cartilage, there may be sore throat. If one side of the thyroid cartilage pterygoid plate and cricothyroid membrane are invaded, the laryngeal cartilage scaffold can be felt on that side, and there is an irritating dry cough. The diagnosis is usually confirmed when the disease has progressed to two areas.
Metastasis
According to the differentiation degree and primary site, laryngeal cancer can spread and metastasize in the following three ways.
① Direct spread: advanced laryngeal cancer often spreads to submucosal infiltration. The supraglottic type of cancer located in the epiglottis can invade the anterior space of the epiglottis, the valley of the epiglottis and the root of the tongue. Aryepiglottic carcinoma spreads outward to the pyriform fossa and lateral wall of laryngopharynx. Vocal hilar carcinoma can invade forward to the anterior commissure and spread to the opposite vocal cord; it can also destroy the thyroid cartilage forward, causing the laryngeal body to expand and infiltrate the soft tissue in front of the neck. Subglottic carcinoma can spread downward to the trachea, and also penetrate the cricothyroid membrane to the anterior cervical muscle layer, develop to both sides and invade the thyroid gland; and involve the anterior wall of esophagus backward.
(2) Lymphatic metastasis: Metastases are mostly found in the lymph nodes at the bifurcation of the common carotid artery in the deep upper neck group, and then develop along the internal jugular vein to the upper and lower lymph nodes. Subsonic carcinoma often metastasizes to the paraglottic lymph node group.
(3) Vascular metastasis: it can metastasize to lung, liver, kidney, bone, pituitary gland, etc. via blood circulation to the whole body.
Pathology
Histologically, squamous cell carcinoma is the most common type of laryngeal cancer, accounting for 95%-98% of the cases, while adenocarcinoma is rare, accounting for 2% of the cases, and undifferentiated carcinoma, lymphosarcoma and fibrosarcoma are rare. Squamous cell carcinoma of the larynx can be divided into three types: in situ carcinoma, early invasive carcinoma and infiltrative carcinoma, depending on its degree of development. In situ carcinoma is rare and can develop into infiltrating carcinoma after a period of time; early infiltrating carcinoma generally consists of in situ carcinoma breaking through the epithelial basement membrane and infiltrating downward and forming a nest in the lamina propria; most of the infiltrating carcinomas of larynx are highly differentiated squamous carcinomas, with different degrees of keratinization and intercellular bridges, and keratinized beads can be seen in the center of the nest, while low differentiated squamous carcinomas are rare. Sometimes the tumor is mainly spindle cell, which is called spindle cell carcinoma. The arrangement of cancer cells is disorderly and does not form a cancer nest, which is quite similar to sarcoma. Warty carcinoma is a subtype of laryngeal invasive squamous cell carcinoma, which is less common and accounts for 1%-2% of laryngeal carcinoma, and the tumor grows into the laryngeal cavity in the shape of warts, forming cauliflower-like masses. Microscopically, it is a highly differentiated squamous carcinoma with different degrees of local infiltration, slow growth and rare metastasis.
Vocal cord carcinoma is the most common among laryngeal carcinomas, about 60%, with better differentiation; most of them are grade I and II, with less metastasis. The incidence rate of supraglottis cancer is about 30%, with poor differentiation of cancer cells and metastasis is more common. Subsonic carcinoma is rare, accounting for about 6%. The tumor may appear papillary, warty or cauliflower-like elevation to the naked eye, and may also form ulcers locally. Secondary carcinoma of the larynx is rare and usually comes from infiltration of thyroid, laryngeal smoke and esophagus. Metastases from distant larynx are rare, but can come from skin melanoma, gastrointestinal adenocarcinoma, breast cancer, adrenal adenoma, lung cancer, etc.
Examination
1.Cervical examination: including the visualization and palpation of laryngeal shape and cervical lymph nodes. The palpation of cervical lymph nodes should be performed according to the distribution pattern of cervical lymph nodes, from top to bottom, from front to back, to clarify the location and size of enlarged lymph nodes.
2.Laryngoscopy: Indirect laryngoscopy is a common clinical method, only when indirect laryngoscopy is unsatisfactory or not easy to take pathology, direct laryngoscopy and fiberoptic light microscope can be used to further understand the tumor invasion in the larynx and can take tissue for pathological examination in a timely manner for suspected disease.
3.Imaging examination.
(1) X-ray examination: X-ray lateral laryngeal film and laryngeal head orthopantomogram can clarify the general location, size and shape of the lesion and changes in the cartilaginous trachea or soft tissue in front of the cervical vertebrae, if necessary, laryngography is feasible.
(2) CTMR examination: It is helpful to clarify the extent of tumor growth in the larynx and the degree of invasion and cervical lymph node metastasis, especially for patients with advanced stage.
(3) Ultrasound tomography: It is a method to identify the location and relationship with surrounding tissues of enlarged lymph nodes in the neck and to follow up after postoperative radiotherapy.
Misdiagnosis of disease
Misdiagnosis of laryngeal cancer often occurs in paraglottic cancer. Tumors that occur in the vocal cord or ventricular cord are usually easy to diagnose. However, because the primary site is hidden, even when the vocal cords are fixed, the tumor cannot be seen, so it is often misdiagnosed as “vocal cord paralysis”, “chronic laryngitis”, “functional aphonia”, etc. The tumor is often misdiagnosed as “vocal cord paralysis”, “chronic laryngitis”, “functional loss of voice”, etc. In some cases, after more than half a year of repeated examination, observation and biopsy, the tumor was not diagnosed until it was protruding from the vocal cord. Therefore, if laryngoscopy reveals that one side of the vocal cord is restricted or fixed, especially if the surface of the ventricular cord is bulging, CT scan should be performed in time. In case of paraglottic carcinoma, the radiograph may show that the laryngeal chambers on one side become linear or report a dense shadow in the paraglottic space, and the pear-shaped fossa becomes narrow or disappears. If conventional laryngoscopic biopsy is negative, microscopic laryngoscopy should be performed to hook the ventricular band with a laryngeal hook, which can better expose the laryngeal choke cavity and biopsy accurately.