What Is the Anatomy of the Glottic Region?
The glottic area of the voicebox or larynx mainly extends from the upper surface of the vocal cords of the larynx and in a horizontal plane to nearly 1 cm below the vocal cord surface. Glottic cancer is a cancerous lesion involving the larynx and is not uncommon, especially in patients with predisposition or lifestyle risk factors. So if the glottis region is impacted by cancer, then usually both the upper as well as lower surfaces of the vocal cords are affected. The anterior and posterior commissures also get impacted. Glottic cancer can be either supraglottic or subglottic based upon the surface affected. However, supraglottic cancer is more common than subglottic cancer.
What Are the Causes and Risk Factors of Glottic Cancer?
Glottic cancer, in terms of etiologic factors, tends to occur more commonly in males, as reported in medical literature and case records. However, male to female prevalence may be equal in the current decade owing to the lifestyle risk factors that precipitate cancer, mainly due to smoking and chronic alcoholism. The smoking population generally is more predisposed than nonsmokers to developing glottic cancers. Smoking and alcoholism have a synergistic impact on alcohol abusers as well as smokers. Research-based evidence points to a two to three-fold increased risk of developing glottic cancer.
The age group most commonly affected is in the sixth decade of life. Still, lifestyles afflicted with detrimental habits can affect individuals of any age group. Furthermore, 40 % of patients presenting with a history of laryngeal cancers or HPV (human papillomavirus) may get affected or predisposed to developing glottic cancer, according to research data collected in recent decades.
Patients with a history of radiation exposure, especially to the head and neck region, or those with occupational hazard exposure to materials like asbestos, mustard gas, wood dust, or petroleum products would be at a major risk of developing glottic cancer. Individuals suffering from comorbid conditions like COPD (chronic obstructive pulmonary disease), chronic hypertension, heart, liver, or kidney diseases may also be considerably less immune and more predisposed to developing glottic cancer.
How Does the Tumor Spread?
Glottic cancer is an invasive tumor and can spread through various paths listed below:
Local Spread
As this cancer arises from the anterior two-third region of the vocal cord, it tends to spread primarily to the anterior commissure and eventually to the opposite vocal cord. The local spread of glottic cancer may be quite aggressive, and the spread to vocal cords may be clockwise or anticlockwise. Tumors of the anterior commissure are more common and can be more erosive, impacting or penetrating the neck's soft tissues than the tumors occurring over the posterior commissure. If the posterior commissure is involved, then the physician or otolaryngologist may diagnose it as an advanced form of supraglottic cancer owing to the uncommon region of occurrence.
Vertical Spread
In this direction, the tumor can spread upwards into the ventricle area, the false cord region, the aryepiglottic region, or even downwards into the subglottic region. When the subglottic region gets involved in the tumor metastases, then subglottic cancer occurs. However, it's a less common condition.
Lateral Spread
The lateral direction spread involves mainly the vocal musculature, the paraglottic space, or the thyroarytenoid muscles. When the tumor penetration is locally extensive, it can potentially erode into the thyroid cartilage, cricothyroid membrane, and the thyroid gland. The strap muscles can also get affected.
Lymphatic Spread
Although nodal metastasis may not be observed in the early stages of glottic cancer, lymph nodes from levels II, III, IV, and VI may get involved usually in the later phases. The deeper the tumor's extension, the greater will be the lymph nodal involvement.
Distant Metastasis
Glottic cancer can be quite aggressive in terms of metastasizing over to distant target tissue into organs like the lungs, liver, or even bones because of mediastinal lymph node involvement, which may aggravate and aid in rapid tumor metastasis. In supraglottic cancers, distant metastasis is common. The ribs, vertebrae, or the skull region can also be affected when the bone gets involved through distant metastasis.
What Are the Clinical Features of Glottic Cancer?
In the initial stages, a patient suffering from glottic cancer may only present with hoarseness of voice and stridor pertaining to the large tumor that obstructs the patient's airway. Oral discomfort can be common. When hoarseness of voice persists for more than two to three weeks, it should be investigated by the healthcare provider. Patients also complain of difficulty in swallowing food or dysphagia. The patient may observe blood-tinged sputum on coughing as the tumor tend to be ulcerative or ulcero-proliferative. Weight loss and loss of appetite are common symptoms.
How to Diagnose Glottic Cancer?
The ideal method would be to perform a CT (computed tomography) scan with or without contrast to aid in an accurate and confirmative diagnosis of glottic cancer lesions. CT scans are the gold standard for assessing glottic tumors' location, size, and extent. Other diagnostic modalities include PET (positron emission tomography) or CT scan for distant metastasis detection, FNAC (fine needle aspiration cytology), and direct endoscopy for biopsy lesions.
What Is the Differential Diagnosis of Glottic Cancer?
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Benign mucosal lesions: Vocal nodules, polyps, granulomas, and amyloidosis.
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Benign neoplasms: Papillomas, haemangiomas, granular cell tumors, lymphangioma, etc.
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Vocal cord leukoplakia.
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Carcinoma in situ of the larynx.
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Laryngeal tuberculosis.
How to Treat or Manage Glottic Cancer?
When the tumor is limited to the T1 stage (only vocal cords) or extends to the T2 stage (supra or subglottic regions), conservative surgery or cordectomy with carbon dioxide laser and complete tumor excision with radiotherapy can help in preserving the voice and improving long-term survival rates. For cancerous lesions of the glottis in T3 and T4 stages (advanced spread lesions with distant metastasis), vertical or total laryngectomy alongside post-operative radiotherapy and chemotherapy is needed. Chemoradiation therapy can be used to preserve the voice of the patients.
Conclusion
To conclude, glottic cancer has the potential for aggressive and distant metastasis and should be treated surgically on time to improve long-term survival rates. In addition, detrimental lifestyle habits such as smoking and alcoholism pose major risk factors for this cancer and should be eliminated.
