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Esophageal Cancer: Squamous Cell Carcinoma

Esophageal adenocarcinoma and squamous cell carcinoma are the two forms of cancer of the esophagus. Of the two, squamous cell carcinoma seems to be the more avoidable form, with major risk factors arising from tobacco and alcohol use and caustic injury to the esophagus.

Until recently, squamous cell carcinoma had been the predominant form of esophageal cancer. In the past two decades, however, the prevalence of adenocarcinomas has begun to increase.

What is Squamous Cell Carcinoma?

Squamous cell carcinoma is a form of cancer that begins in the epithelial, or outer, layer of various tissues in the body. This type of cancer is particularly significant, due to its ability to metastasize, or spread to other areas of the body.

Causes and Risk Factors

Unlike esophageal adenocarcinomas, the major risk factors associated with squamous cell carcinomas are well understood and include the following:

Alcohol abuse, especially when combined with smoking, increases the risk for squamous cell carcinomas. Both alcohol and tobacco cause constant irritation of the esophagus, which can lead to cancer.
An increased risk for squamous cell carcinoma of the esophagus is also seen in people with achalasia. Achalasia is a disorder in which the barrier between the esophagus and stomach fails to relax so that the esophagus cannot properly move food down to the stomach.
Patients who have a history of breast cancer or lymphomas are at an increased risk for squamous cell carcinomas, with the recurrent cancer developing 10 or more years following radiotherapy.
Since any substance or activity that causes irritation to the esophagus can increase the risk for developing squamous cell carcinomas, people who have ingested lye or any other caustic (burning) fluids should be wary of its development.
The only known genetic contributor to esophageal squamous cell carcinoma is tylosis (nonedpidermolytic palmoplantar keratoderma), a rare dominant disorder.
Tobacco use is associated with a higher risk of developing the cancer, with risk rising with the quantity of tobacco used per day. Among former tobacco users who quit, the risk of developing squamous cell carcinomas is greatly diminished.

Changes in diet can help reduce the risk of developing esophageal cancer by as much as half, especially by replacing preserved, high-salt foods with fresh fruits and vegetables.

Symptoms of Squamous Cell Carcinoma

Early stages of squamous cell carcinoma often have no symptoms. Symptoms of more advanced stages include:

bloody coughchronic cough
difficult or painful swallowing (dysphagia)
hoarseness
pain in the bottom of the throat, behind the top of the sternum (breastbone) or in the upper back
vomiting
weight loss.

Diagnosis of Squamous Cell Carcinoma

An initial diagnosis of squamous cell carcinoma is usually conducted with an esophagogram, a procedure that requires the patient to drink liquid barium. The esophagogram reveals any ulceration or narrowing of the esophagus. A biopsy is taken if cancer is suspected.

An upper endoscopy may be performed to view the esophagus and look for ulcers. It involves the use of an endoscope, which is a fiber-optic cable attached to a video camera.

In cases where the cancer may be confined to the esophagus, endoscopic ultrasonography (ultrasound) may be used to determine how deep the tumor has gone and whether it has spread to the surrounding tissues.

A computed tomographic (CT) scan of the chest, abdomen and pelvis can help determine whether the cancer has metastasized. Additionally, positron-emission tomography (PET) scans can be used to examine the lymph nodes and other sites for metastases that might not be detected in the CT scan or ultrasonography.

Treatment of Squamous Cell Carcinoma

Once squamous cell carcinoma has developed, it can be treated but not cured. Prognosis is usually poor. Treatment involves either surgery or a combination of chemotherapy with radiation treatment. Clinical trials of combined surgical and chemotherapy are under way, though results thus far have not shown significant advantages for combination treatments:

Surgery: Surgical resection of the esophagus is used when the cancer is localized to a small area with no metastases. The five-year survival rate for patients who have undergone surgical treatment for esophageal cancer ranges from 5 percent to 30 percent, although patients with very early diagnoses have better prognoses.

In cases where patients have a history of head and neck cancer or a history of ingesting caustic substances, careful following of the progress of the disease can lead to early detection of squamous cell carcinomas, allowing surgical removal before the cancer progresses. Once symptoms are present, however, the cancer has usually invaded more tissues and may have already metastasized to new sites in the body, making surgery less feasible.
Chemotherapy and Radiation Therapy: Radiation therapy alone is insufficient to control squamous cell carcinoma. Chemotherapy combined with radiation therapy allows a much better five-year survival rate As a result, the outcomes for combined chemotherapy and radiotherapy are similar to those for surgical intervention.

Resources

Enzinger, P. C., Mayer, R. J. (2003). Esophageal Cancer. The New England Journal of Medicine, 349 (23), 2241-2252.

National Cancer Institute. (n.d.). Esophageal Cancer. Retrieved June 20, 2007 from http://www.cancer.gov/cancertopics/types/esophageal/.

University of Utah Health Care. (October 2001). Digestive Disorders – Esophageal Cancer. Retrieved June 20, 2007 from http://healthcare.utah.edu/healthinfo/adult/digest/esophcan.htm.

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