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Understanding Adenocarcinoma

Adenocarcinoma is a form of cancer that begins in the tissues of glands or secretory cells. Secretory cells are cells that release a product, such as saliva, hormones or proteins.

Esophageal adenocarcinomas are believed to be formed when the acidic contents of the stomach enter the esophagus. Over a long period of time, stomach acids may damage the epithelial cells that line the esophagus. This damage can lead to the formation of cancerous cells.

Causes and Risk Factors for Adenocarcinoma

Current research is seeking to find specific risk factors for esophageal adenocarcinomas. However, since adenocarcinomas are associated with persistent reflux of gastric contents into the esophagus, researchers consider diseases that feature such acid reflux disease to be significant risk factors.

Gastroesophageal reflux disease (GERD) is one such disease. This condition results when the anti-reflux barrier between the esophagus and the stomach fails to work properly. These failures can be either temporary or permanent. When they are permanent, the risk of developing adenocarcinomas is eight times greater than normal.

When GERD is a chronic condition, Barrett's esophagus develops in roughly 5 percent to 8 percent of cases. Barrett's esophagus occurs when the epithelial cells of the esophagus are damaged to the point that they are abnormal and come to resemble the cells in the intestine (colonic columnar cells). Adenocarcinoma is seen at a rate of 30 to 125 times higher in patients who have Barrett's syndrome than in patients who don't have the condition.

In addition to reflux diseases, tobacco use and obesity have been implicated as risk factors in the development of adenocarcinoma. Among former tobacco users who quit, the risk of developing adenocarcinoma does not diminish, although quitting does lower the risk for squamous cell carcinoma.

Also, patients who have a history of breast cancer or lymphomas are at an increased risk for adenocarcinoma, with the recurrent cancer typically developing 10 or more years following radiotherapy.

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 Adenocarcinoma

Early stages of adenocarcinoma often have no symptoms. Symptoms of more advanced stages include:

bloody cough
chronic cough
difficult or painful swallowing (dysphagia)
GERD
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 Adenocarcinoma

An esophagogram, in which the patient drinks liquid barium, is typically used to diagnose adenocarcinoma. An esophagogram reveals whether an ulceration or a narrowing of the esophagus exists. Biopsies can be taken to determine what form of cancer is present.

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

In cases where the cancer is restricted to the esophagus, endoscopic ultrasonography (ultrasound) may be used to determine how deep the tumor has gone and whether it has metastasized or 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 Adenocarcinoma

Once adenocarcinoma has developed, it can be treated but not cured. The prognosis is usually poor. Treatment involves either surgery or a combination of chemotherapy and radiation treatment. Clinical trials of surgical and chemotherapy combinations are under way, though results thus far have not shown a significant advantage:

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 of esophageal cancer ranges from 5 percent to 30 percent, although patients with very early diagnoses have better prognoses.

In cases where patients present with Barrett's esophagus, careful following of the progress of the disease can lead to early detection of adenocarcinomas, 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 beneficial.
Chemotherapy & Radiation Therapy: Radiation therapy alone is insufficient to control adenocarcinoma. Chemotherapy combined with radiation therapy allows a much better five-year survival rate. According to one study, the combination of chemotherapy and radiation resulted in a 26 percent five-year survival rate, compared with zero percent for radiation alone. The results of combined chemotherapy and radiotherapy are statistically similar to the results of 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/.

National Cancer Institute. (2007). Esophageal Cancer: General Information. Retrieved June 20, 2007, from http://www.cancer.gov/cancertopics/pdq/treatment/
esophageal/HealthProfessional/page1.

National Cancer Institute. (2007). Esophageal Cancer: Prevention. Retrieved June 20, 2007, from http://www.cancer.gov/cancertopics/pdq/prevention/
esophageal/HealthProfessional#Reference1.8.

National Cancer Institute. (2007). Esophageal Cancer: Treatment. Retrieved June 20, 2007, from http://www.cancer.gov/cancertopics/pdq/treatment/
esophageal/HealthProfessional/page4.

National Digestive Diseases Information Clearinghouse. (2004). Barrett's Esophagus. Retrieved June 20, 2007, from http://digestive.niddk.nih.gov/ddiseases/pubs/barretts/index.htm.

National Digestive Diseases Information Clearinghouse. (2007). Heartburn, Gastroesophageal Reflux (GER), and Gastroesophageal Reflux Disease (GERD). Retrieved June 20, 2007, from http://digestive.niddk.nih.gov/ddiseases/pubs/gerd/.

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

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