43 Laryngeal Carcinoma
43.1 Pathology
Squamous cell carcinoma of the larynx represents approximately 1% of all malignancies in men. It is about five times commoner in males than in females. The incidence increases with age, with three-quarters of all diagnoses in patients over 60, but the peak age of presentation is not until the eighth decade. Tobacco and alcohol, individually and synergistically, are the main causes. In contrast to oropharyngeal cancer, it appears that human papilloma virus infection is not a major cause. There are other histological tumours of the larynx in addition to squamous cell carcinoma. Verrucous carcinoma is a distinct variant of well-differentiated squamous cell carcinoma. Adenocarcinoma, adenoid cystic carcinoma, fibrosarcoma, chondrosarcoma and lymphomas are all rare.
For classification purposes, the larynx is divided into three regions of which each includes a number of subsites:
1. Supraglottis: This comprises the larynx superior to the apex of the ventricle. It includes the ventricle, vestibular folds, arytenoids, aryepiglottic folds and the epiglottis (laryngeal surface, tip and lingual surface).
2. Glottis: This comprises the vocal cords and the anterior and posterior commissures. It extends from the apex of the laryngeal ventricle to 1 cm below. Some authorities hold that the superior and inferior borders of the glottis correspond to the superior and inferior arcuate lines, respectively.
3. Subglottis: This extends from the inferior border of the glottis to the lower border of the cricoid cartilage.
43.2 Clinical Features
The clinical features of malignant disease are dictated by the primary tumour, secondary deposits and the general effects of cancer. The symptoms and signs of a laryngeal tumour depend on the subsite involved and the way in which it is related to the upper aerodigestive tract. Hoarseness is the commonest, and often the only, presenting symptom. Dyspnoea and stridor are late symptoms and usually indicate an advanced tumour. Pain is an uncommon symptom but may occur with supraglottic tumours. Patients with a cancer in this site may complain of a unilateral sore throat and there may be referred otalgia. Dysphagia indicates invasion of the pharynx. Swelling of the neck may be due to direct penetration of the tumour outside the larynx or to lymph node metastases. Cough and throat irritation are occasional symptoms. Anorexia, cachexia and foetor imply advanced disease.
There should be a general examination to identify distant metastases and an assessment of the overall physical status of the patient. Fibre-optic laryngoscopy should allow an inspection of the primary tumour site and size. Vocal cord mobility should also be assessed. The two areas which are difficult to examine by this technique are the subglottis and the laryngeal ventricle and should be carefully examined at microlaryngoscopy under general anaesthesia. The neck should be carefully palpated for the presence of enlarged lymph nodes. Examination must include an assessment of the number, mobility and level of the nodes. Laryngeal tumours usually metastasise to the upper deep cervical lymph nodes, but supraglottic tumours may cause bilateral nodes, and some subglottic tumours may spread to the upper mediastinal nodes.
43.3 Investigations
1. Blood tests A full blood count and serum analysis are baseline investigations. The serum analysis may show deranged liver function raising suspicion of liver metastases, or hypoproteinemia, which may indicate malnourishment and a possibility of poor wound healing.
2. Magnetic resonance imaging (MRI) or computed tomography (CT) scans of the larynx and neck provide further information about the primary tumour. Both modalities are acceptable, and choice often depends on local protocols. MRI with contrast is preferable to show soft tissue disease, but high-resolution CT is useful in evaluation of the integrity of thyroid cartilage. Imaging may also detect the presence of impalpable or occult nodes. A CT scan of the chest and upper abdomen is required to exclude metastases and to assess intercurrent lung disease. Distant metastases are unusual in laryngeal carcinoma (1–5%).
3. At microlaryngoscopy, the patient should have all the larynx subsites inspected systematically. It should routinely involve the use of straight (0-degree), and angled (30- or 70-degree) endoscopes. Photographs should be taken and the tumour’s position and extension should be recorded by means of diagrams in the case notes. An adequate and representative biopsy is essential for accurate histology. While the patient’s neck muscles are relaxed under general anaesthetic, the neck should be palpated for nodes which may not have been noted previously. Cord mobility should be assessed as the patient wakes, if not recorded previously.
The information obtained will allow tumour staging according to the current UICC/AJCC TNM classification and appropriate management.
43.4 Staging
Laryngeal tumours are diverse in their behaviour and prognosis and thus there have been many endeavours to classify them. Clinical staging attempts to group together features which may share prognosis or certain treatments. In cancer of the larynx, clinical staging is the only generally reliable criterion of any prognostic significance, but some parts of the T staging are subjective. Therefore, even with this standard, there may be considerable variability between surgeons in T-stage assignment for a given tumour, particularly in T3 tumours. An accurate anatomical description of tumour extent (with a case file diagram and photograph) is therefore essential in treatment selection. The 8th edition of the UICC/AJCC staging system defines T stage as listed below.
43.4.1 Supraglottis
T1 | Tumour limited to one subsite of the supraglottis. |
T2 | Invasion of more than one subsite of the supra-glottis or glottis or adjacent region outside the supraglottis (e.g., mucosa of tongue base). |
T3 | Confined to larynx with a fixed vocal cord or invades the post-cricoid area, pre-epiglottic or paraglottic space, base of tongue, inner cortex of thyroid cartilage. |
T4a | Extends beyond the larynx. Invading through thyroid cartilage and/or trachea, soft tissues of the neck including extrinsic tongue muscles, strap muscles, thyroid gland and oesophagus. |
T4b | Tumour invades prevertebral space, encases carotid artery or mediastinal structures. |
43.4.2 Glottis
T1(a) | Tumour limited to one vocal cord. |
T1(b) | Involves both vocal cords. |
T2 | Tumour extends to supraglottis and/or subglottis or impaired cord mobility. |
T3 | Confined to the larynx with a fixed vocal cord and/or invades paraglottic space and/or inner cortex of thyroid cartilage. |
T4a | Extends beyond the larynx. Invading through thyroid cartilage and/or trachea, soft tissues of the neck including extrinsic tongue muscles, strap muscles, thyroid gland and oesophagus. |
T4b | Tumour invades prevertebral space, encases carotid artery or mediastinal structures. |
43.4.3 Subglottis
T1 | Tumour limited to subglottis. |
T2 | Extends to vocal cords with normal or impaired mobility. |
T3 | Limited to larynx with vocal cord fixation. |
T4a | Extends beyond the larynx. Invading through thyroid cartilage and/or trachea, soft tissues of the neck including extrinsic tongue muscles, strap muscles, thyroid gland and oesophagus. |
T4b | Tumour invades prevertebral space, encases carotid artery or mediastinal structures. |
N stage is identical to that of other head and neck sites and covered in Chapter 9, Cervical Lymphadenopathy.
Stage grouping is based on the TNM status:
