Squamous cell carcinoma of head and neck

Synonyms

3

Overview

Cancers that are known collectively as head and neck cancers usually begin in the squamous cells that line the moist, mucosal surfaces inside the head and neck (for example, inside the mouth, the nose, and the throat). These squamous cell cancers are often referred to as squamous cell carcinomas of the head and neck. At least 75 % of head and neck cancers are caused by tobacco and alcohol use. Infection with cancer-causing types of human papillomavirus (HPV), especially HPV-16, is a risk factor for some types of head and neck cancers. The symptoms of head and neck cancers may include a lump or a sore that does not heal, a sore throat that does not go away, difficulty in swallowing, and a change or hoarseness in the voice. Treatment for head and neck cancer can include surgery, radiation therapy, chemotherapy, targeted therapy, or a combination of treatments.

Symptoms

Throat cancer usually begins with symptoms that seem harmless enough, like an enlarged lymph node on the outside of the neck, a sore throat or a hoarse sounding voice. However, in the case of throat cancer, these conditions may persist and become chronic. There may be a lump or a sore in the throat or neck that does not heal or go away. There may be difficult or painful swallowing. Speaking may become difficult. There may be a persistent earache. Other possible but less common symptoms include some numbness or paralysis of the face muscles.

Presenting symptoms include

  • Mass in the neck
  • Neck pain
  • Bleeding from the mouth
  • Sinus congestion, especially with nasopharyngeal carcinoma
  • Bad breath
  • Sore tongue
  • Painless ulcer or sores in the mouth that do not heal
  • White, red or dark patches in the mouth that will not go away
  • Earache
  • Unusual bleeding or numbness in the mouth
  • Lump in the lip, mouth or gums
  • Enlarged lymph glands in the neck
  • Slurring of speech (if the cancer is affecting the tongue)
  • Hoarse voice which persists for more than six weeks
  • Sore throat which persists for more than six weeks
  • Difficulty swallowing food
  • Change in diet or weight loss

Causes

Alcohol and tobacco use are the most common risk factors for head and neck cancer in the United States. Alcohol and tobacco are likely synergistic in causing cancer of the head and neck. Smokeless tobacco is an etiologic agent for oral and pharyngeal cancers (oropharyngeal cancer). Cigar smoking is an important risk factor for oral cancers as well. Other potential environmental carcinogens include occupational exposures such as nickel refining, exposure to textile fibers, and woodworking. In one large, controlled study, marijuana use was not shown to be associated with oral squamous cell carcinoma. In another study, marijuana use was shown to be a potential protective factor against the development of head and neck squamous cell carcinoma. However, cigarette smokers have a lifetime increased risk for head and neck cancers that is 5- to 25-fold increased over the general population. The ex-smoker's risk for squamous cell cancer of the head and neck begins to approach the risk in the general population twenty years after smoking cessation. The high prevalence of tobacco and alcohol use worldwide and the high association of these cancers with these substances makes them ideal targets for enhanced cancer prevention.

Prevention

  • Tobacco use, alcohol use, and human papillomavirus infection are important risk factors for head and neck cancers.
  • Avoidance of recognised risk factors (as described above) is the single most effective form of prevention. Regular dental examinations may identify pre-cancerous lesions in the oral cavity.
  • When diagnosed early, oral, head and neck cancers can be treated more easily and the chances of survival increase tremendously.
  • It is expected that HPV vaccines may reduce the risk of HPV induced head and neck cancer.

Diagnosis

A patient usually presents to the physician complaining of one or more of the above symptoms. The patient will typically undergo a needle biopsy of this lesion, and a histopathologic information is available, a multidisciplinary discussion of the optimal treatment strategy will be undertaken between the radiation oncologist, surgical oncologist, and medical oncologist.

Histopathology:

Throat cancers are classified according to their histology or cell structure, and are commonly referred to by their location in the oral cavity and neck. This is because where the cancer appears in the throat affects the prognosis - some throat cancers are more aggressive than others depending upon their location. The stage at which the cancer is diagnosed is also a critical factor in the prognosis of throat cancer.

Squamous cells are the epithelium that is the surface cells of much of the body. Skin and mucous membranes are squamous cells. This is the most common form of larynx cancer, accounting for over 90% of throat cancer. Squamous cell carcinoma is most likely to appear in males over 40 years of age with a history of heavy alcohol use coupled with smoking.

Prognosis

Head and neck squamous cell carcinoma (HNSCC) develops from the mucosal linings of the upper aerodigestive tract, comprising 1) the nasal cavity and paranasal sinuses, 2) the nasopharynx, 3) the hypopharynx, larynx, and trachea, and 4) the oral cavity and oropharynx. Squamous cell carcinoma (SCC) is the most frequent malignant tumor of the head and neck region. HNSCC is the sixth leading cancer by incidence worldwide. There are 500000 new cases a year worldwide. Two thirds occur in industrialized nations. HNSCC usually develops in males in the 6th and 7th decade. It is caused by tobacco and alcohol consumption and infection with high-risk types of human papillomavirus (HPV). SCC often develops from preexisting dysplastic lesions. The five-year survival rate of patients with HNSCC is about 40-50%.

Treatment

Improvements in diagnosis and local management, as well as targeted therapy, have led to improvements in quality of life and survival for head and neck cancer patients since 1992.

After a histologic diagnosis has been established and tumor extent determined, the selection of appropriate treatment for a specific cancer depends on a complex array of variables, including tumor site, relative morbidity of various treatment options, patient performance and nutritional status, concomitant health problems, social and logistic factors, previous primary tumors, and patient preference. Treatment planning generally requires a multidisciplinary approach involving specialist surgeons and medical and radiation oncologists.

Several generalizations are useful in therapeutic decision making, but variations on these themes are numerous. Surgical resection and radiation therapy are the mainstays of treatment for most head and neck cancers and remain the standard of care in most cases. For small primary cancers without regional metastases (stage I or II), wide surgical excision alone or curative radiation therapy alone is used. More extensive primary tumors, or those with regional metastases (stage III or IV), planned combinations of pre- or postoperative radiation and complete surgical excision are generally used. More recently, as historical survival and control rates are recognized as less than satisfactory, there has been an emphasis on the use of various induction or concomitant chemotherapy regimens.

Patients with head and neck cancer can be categorized into three clinical groups: those with localized disease, those with locally or regionally advanced disease, and those with recurrent and/or metastatic disease. Comorbidities (medical problems in addition to the diagnosed cancer) associated with tobacco and alcohol abuse can affect treatment outcome and the tolerability of aggressive treatment in a given patient.

Many different treatments and therapies are used in the treatment of throat cancer. The type of treatment and therapies used are largely determined by the location of the cancer in the throat area and also the extent to which the cancer has spread at time of diagnosis. Patients’ also have the right to decide whether or not they wish to consent to a particular treatment. For example, some may decide to not undergo radiation therapy which has serious side effects if it means they will be extending their lives by only a few months or so. Others may feel that the extra time is worth it and wish to pursue the treatments.

Surgery:

Surgery as a treatment is frequently used in most types of head and neck cancer. Usually the goal is to remove the cancerous cells entirely. This can be particularly tricky if the cancer is near the larynx and can result in the patient being unable to speak. Surgery is also commonly used to resect (remove) some or all of the cervical lymph nodes to prevent further spread of the disease.

CO2 laser surgery is also another form of treatment. Transoral laser microsurgery allows surgeons to remove tumors from the voice box with no external incisions. It also allows access to tumors that are not reachable with robotic surgery. A microscope helps the surgeon clearly view the margins of the tumor, minimizing the amount of normal tissue removed or damaged during surgery. This technique helps give the patient as much speech and swallowing function as possible after surgery.

Radiation therapy:

Radiation mask used in treatment of throat cancer

Radiation therapy is the most common form of treatment. There are different forms of radiation therapy, including 3D conformal radiation therapy, intensity-modulated radiation therapy, and brachytherapy, which are commonly used in the treatments of cancers of the head and neck. Most patients with head and neck cancer who are treated in the United States and Europe are treated with intensity-modulated radiation therapy using high energy photons.

Chemotherapy:

Chemotherapy in throat cancer is not generally used to cure the cancer as such. Instead, it is used to provide an inhospitable environment for metastases so that they will not establish in other parts of the body. Typical chemotherapy agents are a combination of paclitaxel and carboplatin. Cetuximab is also used in the treatment of throat cancer.

Docetaxel-based chemotherapy has shown a very good response in locally advanced head and neck cancer. Taxotere is the only taxane approved by US FDA for Head and neck cancer, in combination with cisplatin and fluorouracil for the induction treatment of patients with inoperable, locally advanced squamous cell carcinoma of the head and neck.

While not specifically a chemotherapy, amifostine is often administered intravenously by a chemotherapy clinic prior to a patient's IMRT radiotherapy sessions. Amifostine protects the patient's gums and salivary glands from the effects of radiation.[citation needed]

Photodynamic therapy:

Photodynamic therapy may have promise in treating mucosal dysplasia and small head and neck tumors.[3] Amphinex is giving good results in early clinical trials for treatment of advanced head and neck cancer.

Targeted therapy:

  • Cetuximab (Erbitux) - FDA-approved indication: For use in combination with radiation therapy, for the treatment of locally or regionally advanced squamous cell carcinoma of the head and neck (SCCHN) and for use as a single agent for the treatment of patients with recurrent or metastatic SCCHN for whom prior platinum-based therapy has failed.
  • Amifostine (Ethyol) - FDA-approved indication: Reduction of the incidence of moderate to severe xerostomia in patients undergoing post-operative radiation treatment for head and neck cancer, where the radiation port includes a substantial portion of the parotid glands.

Resources

Refer to Research Publications.