What is Glottic Cancer?
Laryngeal cancers, which are cancers in the throat, are one of the most common types of head and neck cancers and make up about 1% of all cancers worldwide. A specific kind of laryngeal cancer called glottic cancer comes from the true vocal cords and the front and back parts of the throat. Just like other throat cancers, smoking and excessive drinking are generally the main causes of glottic cancer. However, glottic cancer is somewhat different as it tends to have a better outlook than other throat cancers because it’s less likely to spread locally, to lymph nodes, or to other parts of the body.
The treatment of glottic cancer can be quite diverse. If caught early, patients might undergo surgery using a transoral laser (a laser that goes through the mouth) or radiation therapy. For more advanced cases, the treatment could involve a combination of chemotherapy and radiation or complete removal of the larynx (throat). Therefore, doctors must have a solid understanding of the structure of the throat and the stages of glottic cancer to offer the most suitable treatment plan for the disease.
What Causes Glottic Cancer?
Smoking and heavy drinking have long been linked to various types of throat cancer, including cancer in your voice box (larynx) and vocal chords (glottic). In fact, smokers are 15-30 times more likely to develop these kinds of cancer compared to non-smokers. And if heavy drinking is also in the mix, then the risk of this cancer significantly increases. Moreover, both of these factors continue to affect the patient even after diagnosis and treatment, leading to worse survival outcomes and higher chances of cancer returning.
Other potential risk factors for these cancers may include acid reflux, low income and socioeconomic status, using opium, eating a lot of red meat, and exposure to certain substances at work. On the other hand, having a healthy diet might provide some small protection from these cancers.
There is some uncertainty over the role of the Human Papillomavirus (HPV) in causing laryngeal cancers compared to its known involvement in other throat cancers. Some large-scale reviews of studies have found that HPV might be linked to about 20-30% of laryngeal cancers. However, this rate can vary a lot depending on the geographical location, and further research is needed to confirm if HPV can definitely cause laryngeal cancers.
Risk Factors and Frequency for Glottic Cancer
Primary laryngeal and glottic cancers, which affect your throat and vocal cords, aren’t common, making up about 1% of cancer cases in men and only 0.3% in women across the globe. In the US alone, the American Cancer Society estimates that there will be 12,370 new cases of throat cancer in 2020. Approximately 60% of these cases start in the vocal cords (glottis). While these numbers are staggering, around 9,820 of these cases will be men while 3,750 individuals, regardless of gender, are expected to pass away due to this disease. The number of cases in men is about four times that of women. But, there’s a silver lining here: the overall number of cases drops by around 2 to 3% every year.
Now, a lot hinges on a person’s socio-economic and racial background as well as where they live. The incidence of throat cancer is higher in men, people with lower income, and African-Americans, who often get diagnosed when the disease is already pretty advanced. Also, geographical location plays its role: there are fewer than half as many cases in England per 100,000 people as there are in Scotland and Northern Ireland (2 compared to 4.2 and 4.3, respectively).
Signs and Symptoms of Glottic Cancer
Glottic cancers, or cancers of the voice box, usually cause symptoms like significant hoarseness even when they’re small, that’s why they are often detected early. In fact, current American and British medical guidelines recommend that if a person experiences continuous hoarseness for 4 and 6 weeks respectively, they should be urgently referred to an ear, nose, and throat specialist. Some medical professionals even suggest a referral if hoarseness lasts for just three weeks.
Patients might also have symptoms like difficulty swallowing, painful swallowing, and ear pain. However, these generally show up with advanced disease when the tumor has grown beyond the voice box. In severe cases, patients might come to the emergency room with stridor (a high-pitched, wheezing sound caused by disrupted airflow) and sudden difficulty breathing. It is important to consider a patient’s past medical history and medication use, as this can give clues about risk factors and also help determine if the person is fit for cancer treatment or major surgery. Evaluating risk factors like smoking and alcohol consumption is important too.
Patients need a thorough examination by an ear, nose, and throat specialist. They will check for issues like lymph nodes that are enlarged in the neck. They will also closely inspect the mouth, throat, and back part of the mouth (oropharynx) to rule out other cancers and check the condition of the teeth. A special procedure called flexible nasal endoscopy is usually done. This helps to check the voice box, noticing if one or more vocal cords are involved, if the vocal cords are moving normally and if there’s spread to regions above (supraglottis) and below (subglottis) the voice box. Video-stroboscopic equipment, which allows detailed viewing of the vocal cords, can also be used to detect subtle changes in vocal cord movement.
Testing for Glottic Cancer
If your doctor suspects that you have glottic cancer, the first step is to obtain a CT scan of your neck and upper body. This test can help the doctor understand the extent of the cancer, such as whether it has spread to surrounding tissues, affected your lymph nodes, or moved to other parts of the body. However, if the cancer is detected early and hasn’t caused notable changes in the voice box, a CT scan may not be very useful.
In some medical centers, an MRI scan is preferred because it can better show the soft tissues in the neck. This can be helpful in assessing whether the cancer has invaded the cartilages of the voice box.
A PET-CT scan can be helpful if the primary site of the cancer isn’t detectable. It’s also used 12 weeks after treatment to evaluate how well the treatment worked.
If you’re being considered for radiation therapy, an x-ray known as an orthopantomogram is performed. This x-ray helps to minimize the risk of a serious bone disease caused by radiation therapy.
However, the definitive way to diagnose glottic cancer is through a procedure known as direct laryngoscopy. You’ll be under general anesthesia, and the doctor will insert a tube-like instrument in your throat to examine the tumor and nearby throat areas in detail. The doctor will also take a small sample of tissue for further examination.
Treatment Options for Glottic Cancer
Early and slow-growing throat cancers, known as T1-2 glottic cancers, can be successfully managed with a single type of treatment. There are two main treatments we use: transoral laser microsurgery (TLM), a type of surgery that uses a laser to remove the cancer, and radiation therapy, which uses high-energy beams to kill cancer cells. Research has shown both methods are equally effective in controlling the disease and patient survival.
The decision on which treatment to use depends on the specific characteristics of the tumor, the expected results, the patient’s preference, and the expertise of the hospital or clinic. TLM is usually done in one day under general anesthesia using a CO2 laser. It has low risks and enables the patient to avoid repeated visits required by radiation therapy. The surgery aims to preserve certain structures in the throat, like the cricoid cartilage and at least one crico-arytenoid joint, essential for breathing and speaking.
On the other hand, the radiation regimens for treating these cancers can differ from place to place. If the tumor is in the front portion of the larynx, an area prone to recurrence, a more focused radiation plan might be required. Radiation, though often associated with temporary side effects, is reported to produce better outcomes regarding voice quality compared to surgery.
Partial laryngectomy, a type of surgery that involves the removal of part of the voice box, is another option but is less common. Patient selection for this type of surgery is crucial owing to certain tumor characteristics that make it unsuitable.
For moderately advanced throat cancers, therapy that preserves the organ (such as chemoradiotherapy, a combination of chemotherapy and radiation) is preferred. Traditionally, these types of cancers were treated with total laryngectomy, complete removal of the larynx. However, studies have shown that the combination of chemotherapy and radiotherapy can yield survivals similar to surgery. For elderly patients, it’s important to consider that chemotherapy can cause significant side effects and reduce its effectiveness, so it’s not routinely used in these cases.
For very advanced throat cancers (T4), surgery in the form of total laryngectomy is generally the chosen treatment. This is because these cancers often spread aggressively to the surrounding tissue, making it difficult to preserve the larynx. Palliative treatment, which focuses on relieving symptoms, might be considered for tumors deemed inoperable. After surgery, additional treatments like radiation or chemotherapy can be used to improve outcomes, particularly in high-risk cases.
The treatment for nodal disease, where cancer has spread to lymph nodes, can vary. It can involve chemoradiotherapy or neck dissection, a surgical procedure to remove lymph nodes in the neck. In some cases, neck dissection is performed before chemoradiotherapy in certain patients with significant neck disease.
What else can Glottic Cancer be?
When trying to identify glottic cancer, doctors need to consider other conditions that might show similar symptoms. These include:
- Different types of laryngeal cancers such as supraglottic, subglottic and transglottic cancers
- Other head and neck cancers, such as those of the hypopharynx and upper esophagus
- Pre-cancerous changes in the glottis, like leukoplakia and low and high-grade dysplasia
- Vocal cord immobility
- Benign (non-cancerous) laryngeal lesions like laryngeal papillomatosis, Reinke edema, vocal cord polyps, cysts, nodules, granuloma, chronic laryngitis, hyperkeratosis, and functional dysphonia
By excluding these conditions, physicians can make a more accurate diagnosis of glottic cancer.
What to expect with Glottic Cancer
Generally speaking, early-stage laryngeal (or voice box) cancer usually has a positive outlook. Studies indicate a survival rate of about 90% for stage 1 and 80% for stage 2 cancers over a span of 5 years, when treated using radiation therapy or surgery that conserves the larynx (voice box).
However, the survival rates are less encouraging for advanced stages of this disease. For instance, a study conducted in 1990 reported a 2-year survival rate of approximately 68% and 64% for advanced stages of laryngeal cancer treated with radiation therapy combined with initial chemotherapy, or laryngectomy (surgery to remove the voice box) followed by radiation therapy.
Interestingly, glottis cancer, which is a type of laryngeal cancer, tends to have slightly better overall survival rates than other types of laryngeal cancers. Over a 5 year period, survival rates for glottis cancer are about 83% for localized stage, 42% for advanced stage and 76% for all stages of the disease. Unfortunately, between the years of 1977 and 2002, survival rates for more widespread glottic cancer have been reported to decline over time.
Possible Complications When Diagnosed with Glottic Cancer
Compared to other forms of larynx (voice box) cancer, glottic cancer is less likely to spread locally or to distant regions. However, it can still lead to significant health problems if not treated. These can include voice changes due to muscle involvement, breathing difficulty, pneumonia from improper swallowing, noisy breathing, and emergencies that require a tube to be placed in the windpipe. Damage to parts of the throat from the growth of the cancer might cause difficulty swallowing and weight loss. In advanced stages, the glottic cancer can potentially involve major blood vessels leading to life-threatening bleeding.
Complications of Glottic Cancer Treatment:
- Voice changes
- Breathing difficulty
- Pneumonia from swallowing problems
- Noisy breathing
- Medical emergencies requiring a tube in the windpipe
- Difficulty swallowing
- Weight loss
- Potential life-threatening bleeding
Chemoradiotherapy, a treatment that combines chemotherapy and radiation, can effectively manage more advanced laryngeal cancer. But this treatment often causes significant side effects and complications. Most commonly, patients may have a dry mouth, mouth sores, pain, and difficulty swallowing. About one in seven patients may need a feeding tube externally attached to the stomach for food intake 1-2 years after the therapy. Scarring, swelling, and narrowing may occur within the upper airways. These can lead to repeating procedures to widen strictures or placing a tube in narrowed airways. Depression, pain, swallowing problems, and speech issues may persist long-term and could significantly affect the patient’s quality of life.
Complications after laser surgery inside the mouth are not uncommon, but usually minor and often result in little harm to the patient. Some examples include local infection and bleeding, opening in the windpipe and air leakage under the skin, a hole between the skin and airway, breathing difficulty, swallowing difficulty, and pneumonia from breathing in food. One rare but serious complication inside of your airway during laser surgery is catching on fire. In advanced cases, surgery to remove the entire voice box carries a high risk of complications, especially in patients who had previous radiation treatment. Renewed complications include holes between the throat and skin, wound and lung infections, bleeding, nerve damage, and blood clots. The long-term effect on quality of life after voice box removal can be significant, as these patients need to learn new ways of eating, breathing, and speaking.
Preventing Glottic Cancer
Drinking too much alcohol and smoking cigarettes greatly increase the risk of developing throat (glottic) cancers. If a person continues to smoke, the treatment results might not be as good, they may not live as long, and the cancer may come back. But there’s good news: if a person stops smoking, their risk decreases over time. If they are able to quit smoking for 1 to 4 years, they can significantly lower their risk of getting laryngeal (related to the voice box) cancer. After about 20 years of not smoking, their risk comes down to that of someone who has never smoked.
