eMedicine Specialties > Radiology > Head/Neck
Laryngeal Carcinoma
Updated: Apr 10, 2007
Introduction
Background
Laryngeal cancer is the most common cancer of the upper aerodigestive tract. The incidence of laryngeal tumors is closely correlated with smoking, as head and neck tumors occur 6 times more often among cigarette smokers than among nonsmokers. The age-standardized risk of mortality from laryngeal cancer appears to have a linear relationship with increasing cigarette consumption. Death from laryngeal cancer is 20 times more likely for the heaviest smokers than for nonsmokers.
Furthermore, active smoking by patients with head and neck cancer is associated with significant increases in the annual rate of second primary tumor development compared to former smokers or nonsmokers. The use of unfiltered cigarettes or dark, air-cured tobacco is associated with further increases in risk.
Although alcohol is a less potent carcinogen than tobacco, alcohol consumption is a risk factor for laryngeal tumors. In individuals who use both tobacco and alcohol, these risk factors appear to be synergistic, and they result in a multiplicative increase in the risk of developing laryngeal cancer.
For excellent patient education resources, visit eMedicine's Cancer and Tumors Center. Also, see eMedicine's patient education article Cancer of the Mouth and Throat.
Pathophysiology
Most squamous cell carcinomas of the larynx result from an exposure to carcinogens, such as tobacco and alcohol, which cause diffuse mucosal changes (field effect).
Frequency
United States
Laryngeal cancers account for approximately 1.2% of all new cancer diagnoses in the United States. According to the most up-to-date data from the Surveillance, Epidemiology, and End Results (SEER) Program (National Cancer Institute), the age-adjusted rate for larynx cancer was 4.0923 cases per 100,000 (in 9 SEER registries) in 1973-2000. The age-adjusted rates for larynx cancer were 4.0375 cases per 100,000 and 6.6844 cases per 100,000 for whites and African Americans, respectively. In the United States, more than half of the cases involve glottic cancer.
International
Age-standardized incidence rates ranged from 2.5 to 17.1 per 100,000 person-years at risk in men and from 0.1 to 1.3 per 100,000 person-years at risk in women in European and Asian countries (Scottish Health Statistics).
Mortality/Morbidity
- The prognosis for small laryngeal cancers that do not have lymph node metastases is good, with cure rates of 75-95%, depending on the site, the size of the tumor, and the extent of infiltration.
- Advanced disease has a worse prognosis. Supraglottic cancers usually manifest late and have a poorer prognosis.
- Patients with a hemoglobin level greater than 13 g/dL before radiation have rates of local control and survival that are higher than those of patients who are anemic.
Race
Laryngeal carcinoma is more common in African Americans than in whites, with a ratio of 3.5:1.
Sex
In the 1950s, the male-to-female ratio in patients with laryngeal cancer was 15:1. This number had changed to 5:1 by the year 2000, and the proportion of women afflicted by the disease is projected to increase in years to come. These changes are likely a reflection of shifts in smoking patterns, with women smoking more in recent years.
Age
Laryngeal cancer most commonly affects men middle-aged or older who are smokers and who use alcohol. The peak incidence is in those aged 50-60 years.
Anatomy
Cartilage
The cartilaginous framework of the larynx includes the thyroid cartilage, cricoid cartilage, arytenoid cartilage, and corniculate cartilage (see Images 1-8).
The conus elasticus (cricovocal ligament) is an elastic membrane that joins the upper surface of the cricoid cartilage, the vocal process of the arytenoid, and the lower thyroid cartilage. It serves as a barrier against inferior invasion of pre-epiglottic fat disease. The anterior commissure tendon extends from the anterior commissure and inserts into the thyroid cartilage.
Regions of the larynx
The larynx is divided into 3 anatomic regions: the supraglottic larynx, the glottis, and the subglottic region.
The supraglottic larynx consists of epiglottis, false vocal cords, ventricles, aryepiglottic folds, and arytenoids. The anatomic borders are as follows: superior, epiglottis; inferiorly, point at which the vocal cord epithelium turns upward to form the lateral wall of the ventricle; anterior, posterior edge of the vallecula superiorly and anterior false cord inferiorly; and posterior, the arytenoids.
The glottic larynx consists of the true vocal cords and anterior commissure. The anatomic borders are as follows: superior, point at which the vocal cord epithelium turns upward to form the lateral wall of the ventricle; inferior, 5 mm below the free margin of the vocal cords; anterior, the anterior commissure, which is usually located within 1 cm of the skin surface (an important consideration in planning for radiation therapy); and posterior, the posterior commissure.
The subglottic larynx consists of the region between the vocal cords and the trachea. The anatomic borders are as follows: superior, 5 mm below the free margin of the vocal cords, and inferior, the inferior aspect of the cricoid cartilage.
Pre-epiglottic fat space
The pre-epiglottic fat is located in the anterior and lateral aspects of the larynx and is often invaded by advanced cancers. The anatomic borders are as follows: superior, hyoid bone and hyoepiglottic ligament; inferior, conus elasticus; anterior, thyrohyoid membrane; posterior, anterior wall of the pyriform sinus; and lateral, thyroid cartilage wall. Invasion of the pre-epiglottic fat has significant surgical implications, so evaluation of this space should be part of any radiologic analysis.
Nerves
The recurrent laryngeal nerve innervates the intrinsic laryngeal muscles. Damage to this nerve causes hoarseness clinically and medialization of the arytenoid cartilage radiographically. Enlargement of the pyriform sinus is an important secondary sign of recurrent laryngeal nerve paralysis. The superior laryngeal nerve innervates the cricothyroid muscle, an extrinsic laryngeal muscle that tenses the true vocal cords. Damage to this nerve produces bowing of the vocal cord.
Lymphatics
The first-echelon lymphatics for the supraglottic larynx are the subdigastric nodes and the middle anterior cervical nodes (level 3), and the second-echelon lymphatics are the lower anterior cervical nodes (level 4).
The glottic larynx contains few lymphatics, and nodal spread occurs only with primary extension to the supraglottis or subglottis. For tumors with spread to the supraglottis, the subdigastric nodes are at risk. For tumors with spread to the anterior commissure and anterior subglottis, the middle and lower anterior cervical nodes, the Delphian node, and the lateral paratracheal nodes are at risk.
The first-echelon lymphatics for the subglottic larynx are the Delphian node, the lower anterior cervical nodes and paratracheal nodes, and the supraclavicular nodes, and the second-echelon lymphatics are the mediastinal nodes.
Glottic and subglottic tumors metastasize to ipsilateral lymph nodes, but supraglottic tumors often spread to nodes on both sides of the neck.
Levels of the neck
The anatomy of the cervical lymph nodes is relevant to the treatment of all laryngeal cancer. The American Joint Committee on Cancer (AJCC) and the American Academy of Otolaryngology–Head and Neck Surgery classification systems are widely used.
The neck is divided into 5 levels: level I includes the submental and submandibular triangles; level II, the superior jugular chain nodes extending from the skull base down to the carotid bifurcation and posteriorly to the posterior border of the sternocleidomastoid muscle; level III, the jugular nodes from the carotid bulb inferiorly to the omohyoid muscle; level IV, the jugular nodes from the omohyoid muscle to the clavicle; and level V, the posterior triangle bounded by the sternocleidomastoid anteriorly, the trapezius posteriorly, and the omohyoid inferiorly.
Radiologists use the hyoid bone as a marker for the carotid bifurcation, and the inferior cricoid cartilage as a marker for the omohyoid muscle, which may be difficult to discern radiographically. The Radiation Therapy Oncology Group, in collaboration with 2 European research groups, has established guidelines for delineation of nodal levels.
Presentation
Most laryngeal cancers arise in the glottic region and are symptomatic early as a result of hoarseness and changes in the voice.
Clinical presentation
For supraglottic tumors, common symptoms include mild odynophagia, mild dysphagia, and mass sensation. Uncommon symptoms include severe dysphagia and aspiration and referred ear pain. The mechanism of the referred ear pain is through the activation of the internal branch of the superior laryngeal branch of cranial nerve X with referral to the auricular nerve of Arnold. The pain is located in the posterior wall of the external auditory canal and posterior pinna.
For glottic and subglottic tumors, the most common presenting symptom is hoarseness of the voice. Uncommon symptoms include odynophagia, referred ear pain, thyroid cartilage pain, and airway obstruction.
Staging system
The AJCC has designated staging by using the tumors, nodes, and metastases (TNM) classification. Definitions for the stages are described below.
Primary tumor, T stage
TX indicates that the primary tumor cannot be assessed; T0 means no evidence of primary tumor; and Tis indicates carcinoma in situ.
In the supraglottis, the T stages are as follows: T1, tumor limited to 1 subsite of the supraglottis with normal vocal cord mobility; T2, tumor invasion of the mucosa of more than 1 adjacent subsite of the supraglottis or glottis or of a region outside the supraglottis (eg, mucosa of base of tongue, vallecula, medial wall of pyriform sinus), without fixation of the larynx; T3, tumor limited to the larynx with vocal cord fixation and/or invasion of any of the postcricoid area or pre-epiglottic tissues; T4, tumor invasion through the thyroid cartilage and/or extension into soft tissues of the neck, thyroid, and/or esophagus.
Subsites include the following: false cords, arytenoids, suprahyoid epiglottis, infrahyoid epiglottis, and aryepiglottic folds (laryngeal aspect).
In the glottis, the T stages are as follows: T1, tumor limited to the vocal cord (may involve anterior or posterior commissure) with normal mobility; T2, tumor extension to the supraglottis and/or subglottis and/or impaired vocal cord mobility; T3, tumor limited to the larynx with vocal cord fixation; and T4, tumor invasion through the thyroid cartilage and/or other tissues beyond the larynx (eg, trachea or soft tissues of the neck, including the thyroid and pharynx).
Stage T1 can be subdivided into T1a, in which the tumor limited to 1 vocal cord and T1b, in which the tumor involves both vocal cords.
In the subglottis, the T stages are as follows: T1, tumor limited to the subglottis; T2, tumor extension to a vocal cord with normal or impaired mobility; T3, tumor limited to the larynx with vocal cord fixation; T4, tumor invasion through cricoid or thyroid cartilage and/or extension to other tissues beyond the larynx (eg, trachea or soft tissues of neck, including the thyroid and esophagus).
Regional lymph nodes, N stage
The N stages are as follows NX, regional lymph nodes cannot be assessed; N0, no regional lymph node metastasis; N1, metastasis in a single ipsilateral lymph node, 3 cm or less in greatest dimension; N2, metastasis in a single ipsilateral lymph node more than 3 cm but not more than 6 cm in greatest dimension, metastases in multiple ipsilateral lymph nodes with none more than 6 cm in greatest dimension, or metastases in bilateral or contralateral lymph nodes none more than 6 cm in greatest dimension; and N3, metastasis in a lymph node more than 6 cm in greatest dimension.
Stage N2 may be further subdivided as follows: N2a, metastasis in a single ipsilateral lymph node more than 3 cm but not more than 6 cm in greatest dimension; N2b, metastasis in multiple ipsilateral lymph nodes, none more than 6 cm in greatest dimension; and N2c, metastasis in bilateral or contralateral lymph nodes, none more than 6 cm in greatest dimension.
Distant metastasis, M stage
MX indicates that distant metastasis cannot be assessed; M0, no distant metastasis; and M1, distant metastasis.
Preferred Examination
Diagnostic workup
The diagnostic workup of an individual with a suspected laryngeal carcinoma should include history taking, physical examination, laboratory tests, and radiologic examination.
History taking should include an inquiry into hoarseness, odynophagia, dysphagia, referred ear pain, thyroid cartilage pain, aspiration, and dyspnea.
Physical examination should include a complete head and neck examination with fiberoptic endoscopy for an assessment of vocal cord fixation and the extent of primary disease. Subglottic disease is usually not well visualized endoscopically. Fullness between hyoid bone and thyroid cartilage suggests involvement of the pre-epiglottic space. Ulceration of the infrahyoid epiglottis or fullness of the vallecula suggests involvement of the pre-epiglottic space. Disappearance of a laryngeal click suggests postcricoid involvement. Localized pain over 1 ala of the thyroid cartilage suggests thyroid cartilage invasion.
Laboratory tests should include determination of the complete blood count and alkaline phosphatase level, and liver function tests should be performed.
Radiologic examination should include cross-sectional imaging (CT or MRI) of the head and neck to delineate the extent of primary disease, the presence of bone or cartilage invasion, and the presence of nodal disease. Imaging is particularly useful for submucosal regions such as the pre-epiglottic space and subglottis. T1 tumors of the glottis may not require imaging, though CT is often used to exclude nodal metastases. Plain chest radiography or chest CT may be used to rule out pulmonary metastasis. Although some authors claim that MRI provides a more accurate depiction of tumor extent, most institutions continue to use CT as the primary cross-sectional modality. Advances in high-resolution multi-channel helical CT have kept CT competitive with MRI. MRI is more sensitive, but less specific, than CT for the diagnosis of cartilage invasion.
Further assessment of carcinomas
Approximately 95% of all laryngeal and hypopharyngeal malignant tumors are squamous cell cancers. Almost all squamous cell carcinomas are diagnosed by means of direct visualization because they arise from the mucosal surface of the larynx. Biopsy performed with direct laryngoscopy can help confirm the diagnosis, but the otolaryngologist is usually sure of the diagnosis by simply visualizing the abnormality, even before the biopsy is performed. In the case of small tumors, the clinician can not only diagnose the problem but also obtain enough information by means of direct visualization to obviate the need for imaging. In some cases, however, landmarks important to therapeutic planning are deep to the mucosa; in these cases, imaging can be helpful.
The information sought at imaging depends on the size and position of the primary tumor and the type of therapy planned. A small tumor without evidence of deep extension does not require imaging because all information needed for the therapeutic decision may be obvious at endoscopy. Treatment options include cord stripping, laser excision or radiation therapy. Alternatively, the lesion may be so large that a total laryngectomy is the only option considered; thus, imaging of the primary lesion is of limited usefulness.
For intermediate-sized lesions, imaging can provide useful information. Radiation therapy remains an option. If surgery is considered, a decision must be made as to whether a patient is a candidate for a voice-sparing partial laryngectomy or whether total laryngectomy is required.
Supraglottic carcinomas are associated with a high incidence of nodal metastases at diagnosis; therefore, complete evaluation of the internal jugular lymph nodes with imaging studies is needed. The reported incidence of clinically positive lymph nodes is 55% at initial diagnosis, with a 16% incidence of bilateral involvement.
Differential Diagnoses
Other Problems to Be Considered
Hyperkeratosis
Papillomas
Polyps
Fibromas
Granulomas
Laryngoceles
Radiography
Findings
Soft tissue radiographs of the neck are good survey studies. Air is used as a natural contrast agent to visualize the lumen of the larynx and trachea. Retropharyngeal tissue thickness can be appreciated. Epiglottis and the aryepiglottic folds are visualized. However, radiography has no role in the current management of laryngeal cancer.
The barium swallow is used to evaluate the pharyngeal wall. The motility and pliability of the pharyngeal wall and the mucosal surfaces are assessed. Tumor infiltration causes lack of pliability or distensibility, as well as mucosal irregularity.
Computed Tomography
Findings
Currently, the imaging of laryngeal cancer includes contrast-enhanced helical CT scanning from the C1 vertebral body to the thoracic inlet, with the section plane parallel to the true vocal cords or the hyoid bone. The section thickness should not exceed 3 mm. Patients should be instructed to breathe quietly. With new multidetector-row CT scanners, collimation can be 1 mm, and the larynx can be imaged in a few seconds, providing near-isometric Z -axis resolution with minimal motion artifacts.
All laryngeal studies should be reconstructed using soft tissue algorithms. The area extending from the thyroid bone to the base of the cricoid cartilage is additionally reconstructed with a high-resolution bone algorithm to evaluate for cartilage invasion by tumor. Intravenous contrast enhancement helps to distinguish vascular structures from lymph nodes.
Magnetic Resonance Imaging
Findings
Anatomy
On coronal MRIs, the junction of the supraglottic and glottic larynx is defined by the upper edge of the thyroarytenoid muscle.
MRI technique
MRI is performed by using an anterior neck surface coil. T1- and T2-weighted images are obtained in the axial and coronal planes by using 3- or 5-mm-thick sections with a 1-mm gap. Peripheral gating and/or flow compensation may be used to decrease artifact from vascular flow.
Unlike CT, portions of the MRI examination should be performed before and after contrast enhancement. On nonenhanced studies, tumors are of intermediate signal intensity and easily distinguished from adjacent fat. After gadolinium enhancement, fat suppression helps in differentiating enhancing tumor from the normal pre-epiglottic and paraglottic fat.
Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have recently been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Fibrosing Dermopathy. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or MRA scans. As of late December 2006, the FDA had received reports of 90 such cases. Worldwide, over 200 cases have been reported, according to the FDA. NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes; joint stiffness with trouble
movingor straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more information, see the FDA Public Health Advisory or Medscape.
Supraglottic carcinomas
Epiglottic carcinomas
The epiglottis is the most frequent location for cancers that arise in the supraglottic larynx. Tumors may arise from either the suprahyoid or infrahyoid epiglottis. Radiographically, these lesions are often exophytic and circumferential masses that, when detected early, are confined to the midline of the supraglottis. On MRI, these lesions are of intermediate signal intensity and homogeneously enhancing with the administration of contrast material.
Advanced lesions may extend superiorly to invade the vallecula and base of the tongue and also laterally to involve the aryepiglottic folds, false vocal cord, and paralaryngeal space. Direct inferior extension to involve the anterior commissure and subglottis is seen only in advanced lesions.
Tumors arising from the epiglottis may extend anteriorly to involve the pre-epiglottic space. This form of spread is facilitated by the presence of numerous foramina that provide access for tumoral invasion. Invasion of the pre-epiglottic space is often difficult to detect by means of clinical examination and, when present, alters the tumor stage (stage T3). Invasion of the pre-epiglottic space is readily seen on MRIs and best evaluated with nonenhanced T1 weighted images, which show replacement of normal high-signal-intensity fat by intermediate-signal-intensity tumor.
Aryepiglottic fold carcinomas
Tumors of the aryepiglottic fold are typically exophytic lesions that, when detected early, are confined laterally along the aryepiglottic fold. Advanced lesions may extend laterally to involve the adjacent wall of the pyriform sinus or medially to invade the epiglottis. These malignancies may also grow superiorly to involve the pharyngoepiglottic folds, and they may eventually involve the suprahyoid portion of the epiglottis. Inferiorly, these lesions may involve the false vocal cords and ventricle.
Advanced lesions may extend to involve the cricoarytenoid joint, resulting in fixation of the true vocal cord. They may invade the laryngeal cartilages, and they may also extend into the base of the tongue and pharyngeal walls.
Radiographically, early lesions are identified as lobulated masses arising from the aryepiglottic fold. Early mucosal lesions may not be depicted on MRIs.
False vocal cord carcinomas
Squamous cell cancers that arise from the false vocal cords and laryngeal ventricle tend to be ulcerative and infiltrative with a limited exophytic component. Deep invasion by such tumors results in their access to the paraglottic space, and this may lead to fixation of the supraglottic larynx. Because of their close proximity, these tumors may extend inferiorly to involve the true vocal cords. Such submucosal spread is often occult on clinical examination, and understaging of the lesions is possible if this extension is undetected before surgery.
Tumors of the false vocal cords may extend laterally to involve the medial wall of the pyriform sinus and medially to the inferior portion of the epiglottis, thereby increasing the likelihood of invasion of the pre-epiglottic space. MRI is well suited for the imaging of false vocal cord carcinomas. Coronal imaging is beneficial for evaluating the superior and inferior extent of these lesions and for evaluating the presence of transglottic spread.
Glottic carcinomas
The true vocal cords are the most common site of laryngeal carcinomas; the ratio of glottic carcinomas to supraglottic carcinomas is approximately 3:1. The anterior portion of the true vocal cord is the most common location of squamous cell cancer, with most lesions occurring along the free margin of the vocal cord. Anteriorly, the tumor may extend to anterior commissure, where it may involve the contralateral true vocal cord.
Advanced lesions arising within the anterior aspect of the vocal cord or tumors arising along the posterior one third of the cord may extend posteriorly to involve the cricoarytenoid joint and interarytenoid region. Tumors may extend inferiorly, either mucosally or submucosally, to involve the subglottic region.
Early superficial mucosal lesions may not be detected with either CT or MRI. Larger lesions may result in thickening of the involved vocal cord.
The combination of coronal and axial images may be used to determine the amount of subglottic extension and the presence of cartilage invasion. Because the mucosa is near the perichondrium of the thyroid cartilage anteriorly and the cricoid cartilage posteriorly, the presence of soft tissue thicker than 1 mm in both of these areas is considered abnormal.
Invasion of the cartilage may be detected with both CT and MRI, and is more common in glottic tumors than in subglottic carcinomas. MRI is more sensitive, but less specific, than CT in demonstrating cartilage involvement. The fatty marrow in the ossified cartilage has high signal intensity on T1-weighted images. Tumor infiltration into the cartilage results in decreased signal intensity of the marrow. If the cartilage is nonossified, T2-weighted images are more helpful because the tumor is usually hyperintense relative to the non-ossified cartilage. Unfortunately, edema may be mistaken for tumor invasion on T2-weighted images.
The likelihood of nodal involvement associated with glottic carcinomas depends on the stage of the tumor. The incidence of early T1 lesions has been reported to be as low as 2%. This figure increases to approximately 20% for T3 and T4 lesions. The lymph nodes most at risk of metastases are those of the internal jugular chain. Paratracheal lymph nodes may be involved in glottic tumors that have significant subglottic spread.
Subglottic carcinomas
Subglottic carcinomas are rare and account for only 5% of all laryngeal carcinomas. The subglottic region is more commonly involved by the direct extension of a glottic or supraglottic carcinoma than by tumors elsewhere.
When present, these lesions are characteristically circumferential and often extend to involve the undersurface of the true vocal cords. They have a tendency for early invasion of the cricoid cartilage and extension through the cricothyroid membrane.
Primary subglottic carcinomas have a propensity to drain to the paratracheal lymph nodes. The reported incidence of clinically positive nodes in patients with subglottic carcinoma is 10%.
Hypopharyngeal carcinomas
Hypopharyngeal tumors can remain relatively asymptomatic for a long time. Extensive submucosal growth is common. At the time of diagnosis, as many as 75% of patients with hypopharyngeal tumors have metastases to cervical lymph nodes. Systemic metastases also develop in 20-40% of patients with hypopharyngeal tumors.
CT or MRI studies of hypopharyngeal cancer may demonstrate tumor that is more extensive than is apparent on clinical examination, usually because of submucosal spread of the cancer. Carcinoma of the hypopharynx is most common in the pyriform sinus (60%), followed by the postcricoid region (25%) and the post-pharyngeal wall (15%).
Tumors of the pyriform sinus
Superficial mucosal extension into the apex of the pyriform sinus is not well seen with cross-sectional imaging, and it is best evaluated by means of endoscopy. A pyriform sinus tumor may spread submucosally into the posterior wall of the hypopharynx, the postcricoid region, or the aryepiglottic fold. Large tumors also extend up into the paraglottic fat, the pre-epiglottic fat, and the base of the tongue. These tumors may erode the posterosuperior cricoid cartilage and invade the upper pole of the thyroid gland. Tumors arising from the lateral wall or apex of the pyriform sinus have often already invaded the thyroid cartilage at the time of diagnosis.
Lesions of the medial wall of the pyriform sinus may spread along the aryepiglottic fold into the false vocal cord and anterior cartilage. They also may grow posteriorly into the postcricoid region and then cross the midline to involve the contralateral pyriform sinus. Medial wall lesions also invade paraglottic and pre-epiglottic fat.
Tumors of the postcricoid region
Tumors confined to the postcricoid region are rare. The exception occurs in patients (mostly women) with Plummer-Vinson syndrome. Often, tumors of the posterior wall invade the posterior larynx (arytenoids and posterior cricoid cartilage), causing vocal cord paralysis and hoarseness. Large tumors concentrically infiltrate and narrow the lumen of the hypopharynx. These tumors may extend to the cervical esophagus. The junction of the postcricoid region with the esophageal verge should be evaluated for tumor involvement.
Degree of Confidence
MRI has several advantages over CT that may be helpful for presurgical planning. The multiplanar capabilities of MRI are superior to the reformations available with traditional CT, although multidetector-row CT shows early promise. Coronal imaging is helpful for determining involvement of the laryngeal ventricle and transglottic spread. Midsagittal images are helpful for demonstrating the relationship between the tumor and the anterior commissure. MRI is also superior to CT for specific tissue characterization. However, the longer imaging time may contribute to image degradation by motion.
Focal sclerosis or low signal intensity on T1-weighted images is suggestive of cartilage involvement. However, the only truly diagnostic finding is involvement of the strap muscles due to anterior extension of the tumor through the cartilage.
Interest in the use of dextran-coated ultrasmall supramagnetic iron oxide (USPIO) to detect metastatic nodal disease is growing. Patients are usually imaged 24-36 hours after the intravenous administration of USPIO. Compared with its noncontrast signal intensities, the signal intensity of a normally functioning lymph node after the administration of USPIO is markedly reduced on T1- and T2-weighted MRI as a result of both T2 relaxation and magnetic susceptibility effects due to the uptake of the iron particles by macrophages. A metastatic lymph node does not have a signal loss on contrast-enhanced images because the macrophages of the node have been replaced.
The reported sensitivity and specificity in detecting nodal metastases are in the range of 87% to 90%, respectively. These results suggest that the use of USPIO contrast agents may become an important adjunct in evaluating metastatic nodal disease.
Nuclear Imaging
Findings
PET with or without CT is emerging as a critical modality in the staging and monitoring of many head and neck cancers. Although PET provides little information about the extent of tumor within the larynx, the detection of metastases and the follow-up of treated patients increasingly relies on these modalities. PET with CT is also becoming a critical component of intensity-modulated radiation treatment (IMRT).
PET imaging relies on the increased glycolytic activity of neoplastic cells. Although highly sensitive, it does not provide the same anatomic detail that CT or MRI does, and therefore, it does not necessarily allow for precise localization of pathology or determination of involved structures within the larynx. Combined PET and CT scanners may help circumvent this limitation.
FDG PET has been used to look for unknown primary lesions and second primaries, to stage disease prior to therapy, to detect residual and or recurrent disease after therapy, to assess the response to therapy, and to detect distant metastases. A significant limitation of 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) PET scanning is its insensitivity to small tumor deposits, in the order of 3-4 mm or less.
To interpret FDG PET images accurately, one must be aware of the normal physiologic distribution of tracer, the spectrum of normal variations in uptake and benign causes of FDG uptake that may be confused with malignancy.
Intervention
Supraglottic cancer
Treatment of the primary tumor
Partial laryngectomy may be feasible in select patients. During supraglottic laryngectomy, the upper portion of the thyroid cartilage and its contents, the false vocal cords, the epiglottis, and the aryepiglottic folds are removed. This surgery can preserve the patient's speech and swallowing, but more extensive resection increases the demands on lung function, limiting the utility of that procedure. Patients with impaired lung function do not tolerate supraglottic laryngectomy well because of the risk of aspiration.
Voice-sparing partial laryngectomy performed for the treatment of a supraglottic primary tumor consists of supraglottic laryngectomy. The incision for this procedure is along the ventricle. The portion above the ventricle is removed. Standard supraglottic laryngectomy is contraindicated when the following are present: (1) exolaryngeal spread, (2) vocal cord fixation, (3) involvement of both arytenoids, (4) a tumor-free margin of less than 3 mm between the inferior aspect of the tumor and the anterior commissure, and (5) invasion of the thyroid or cricoid cartilage.
In patients with T1 or T2 tumors, local control rates with conventional fractionated radiation therapy (65-70 Gy in 6-7 wk) are higher than 80% overall. T3 tumors may also be treated with radiation therapy. More-advanced disease requires combined-modality treatment often entailing total laryngectomy. Radiation therapy or induction chemotherapy followed by radiation therapy may be offered with curative intent.
Treatment of the neck
Treatment of the neck is necessary because of the high incidence of cervical metastases. About one third of clinically negative necks have metastatic neck nodes, and the incidence of recurrence in the untreated neck is high. In the surgical treatment of T1 or T2 primary tumors, bilateral modified radical neck dissection is recommended.
Glottic cancer
Treatment of the primary tumor
A variety of surgical procedures are available for treating glottic carcinomas. Advanced lesions are treated with total laryngectomy. Early lesions may be treated with radiation therapy or surgery, such as cordectomy or hemilaryngectomy. Hemilaryngectomy involves resection of the affected true vocal cord along with ipsilateral arytenoids cartilage; this is performed in early glottic cancers. The overlying thyroid ala and its external perichondrium is included in the resection.
Contraindications to standard hemilaryngectomy include the following: (1) tumor extension across the anterior commissure to involve more than one third of the contralateral true cord, (2) subglottic extension more than 10 mm anteriorly and 5 mm posterolaterally, (3) involvement of the cricoarytenoid joint or interarytenoid region; and (4) invasion of the thyroid cartilage.
Carcinoma in situ is highly curable with microexcision, laser vaporization, or radiation therapy. Treatment recommendations should be based on the extent of local disease. Multiple recurrences should suggest an invasive component, and partial or total laryngectomy should be used. T1 and T2 tumors may be treated by means of partial laryngectomy or radiation therapy (65-70 Gy in 6.5-7 wk).
T3 lesions are being treated with primary radiation therapy, followed by salvage laryngectomy if residual disease or recurrence is present. Induction chemotherapy followed by radiation can also be used to preserve the larynx. T4 disease is best treated with total laryngectomy.
Treatment of the neck
Because of the sparse lymphatic network and the low incidence of cervical metastases, elective neck dissection is indicated only for transglottic lesions. Palpable nodal disease requires treatment of the neck.
Subglottic cancer
Total laryngectomy with neck dissection is the usual treatment recommendation. Combination therapy (surgery plus adjuvant radiation therapy) is recommended for more advanced disease.
Multimedia
Media file 1: Image shows membranes of the larynx. Courtesy of Wesley Norman, PhD, DSc.
Media file 2: Anterior view of the laryngeal skeleton. Courtesy of Wesley Norman, PhD, DSc.
Media file 3: Posterior view of the laryngeal skeleton. Courtesy of Wesley Norman, PhD, DSc.
Media file 4: Sagittal view of the larynx. Courtesy of Wesley Norman, PhD, DSc.
Media file 5: Sagittal view of the larynx. Courtesy of Wesley Norman, PhD, DSc.
Media file 6: Posterior view of the laryngeal muscles. Courtesy of Wesley Norman, PhD, DSc.
Media file 7: Anterior view of the laryngeal muscles. Courtesy of Wesley Norman, PhD, DSc.
Media file 8: Lateral radiograph of the neck showing the different structures of the larynx: a, vallecula; b, hyoid bone; c, epiglottis; d, pre-epiglottic space; e, ventricle (air-space between false and true cords); f, arytenoid; g, cricoid; and h, thyroid cartilage.
Media file 9: CT scan shows tumoral involvement of the right vocal cord.
Media file 10: CT scan shows a subglottic cancer along the cricoid cartilage.
References
Castelijns JA, Gerritsen GJ, Kaiser MC, et al. Invasion of laryngeal cartilage by cancer: comparison of CT and MR imaging. Radiology. Apr 1988;167(1):199-206. [Medline].
Castelijns JA, van den Brekel MW, Niekoop VA, Snow GB. Imaging of the larynx. Neuroimaging Clin N Am. May 1996;6(2):401-15. [Medline].
Curtin HD. Imaging of the larynx: current concepts. Radiology. Oct 1989;173(1):1-11. [Medline].
Horowitz BL, Woodson GE, Bryan RN. CT of laryngeal tumors. Radiol Clin North Am. Mar 1984;22(1):265-79. [Medline].
Som PM, Curtin HD. Larynx. Head and Neck Imaging. 4th ed. St Louis: Mosby-Year Book;. 2003: 1595-699.
Keywords
cancer of the larynx, laryngeal cancer, laryngeal tumor, glottic tumor, glottic cancer, subglottic tumor, head and neck cancer, smoking, throat cancer
Contributor Information and Disclosures
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Nasir Iqbal, MD, Assistant Professor, Department of Radiology, Section of MRI, Loyola University Medical Center
Nasir Iqbal, MD is a member of the following medical societies: Radiological Society of North America
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Simon Lo, MD, Assistant Professor, Department of Radiation Oncology, Indiana University School of Medicine
Simon Lo, MD is a member of the following medical societies: American College of Radiology, American Medical Association, American Society for Therapeutic Radiology and Oncology, and Radiological Society of North America
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Arthur J Frazier, MD, Assistant Professor of Radiation Oncology, Residency Program Director, Wayne State University School of Medicine; Radiation Oncologist, Barbara Ann Karmanos Cancer Institute, Gershenson Radiation Oncology Center, Harper Hospital/DMC
Arthur J Frazier, MD is a member of the following medical societies: American Society for Therapeutic Radiology and Oncology
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Harold E Kim, MD, Assistant Professor, Department of Radiation Oncology, Wayne State University School of Medicine; Clinical Chief, DMC-Crittenton Radiation Oncology Center, Harper Hospital
Harold E Kim, MD is a member of the following medical societies: American Association for Cancer Research, American Society for Therapeutic Radiology and Oncology, and American Society of Clinical Oncology
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Michelle L Mierzwa, MD, Staff Physician, Department of Radiology, University Hospital, University of Cincinnati
Michelle L Mierzwa, MD is a member of the following medical societies: Lawson-Wilkins Pediatric Endocrine Society
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Ayesha Waheed, MD,
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Sameer R Keole, MD, Staff Physician, Department of Radiation Oncology, Gershenson Radiation Oncology Center, Karmanos Cancer Institute, Harper Hospital, Wayne State University School of Medicine
Sameer R Keole, MD is a member of the following medical societies: American Society for Therapeutic Radiology and Oncology
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Medical Editor
Barton F Branstetter IV, MD, Assistant Professor of Radiology and Otolaryngology, University of Pittsburgh; Director of Head and Neck Imaging, Associate Director of Informatics, Department of Radiology, Division of Neuroradiology, University of Pittsburgh Medical Center
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