Esophageal cancer

Esophageal cancer is malignancy of the esophagus. There are various subtypes. Esophageal tumors usually lead to dysphagia (difficulty swallowing), pain and other symptoms, and are diagnosed with biopsy. Small and localized tumors are treated with surgery, and advanced tumors are treated with chemotherapy, radiotherapy or combinations. Prognosis depends on the extent of the disease and other medical problems, but is fairly poor.

 Classification 

Esophageal cancers are typically carcinomas, which arise from the epithelium, or surface lining of the esophagus. Most esophageal cancer fall into one of two classes: squamous cell carcinomas, which are similar to head and neck cancer in their appearance and association with tobacco and alcohol consumption, and adenocarcinomas, which are often associated with a history of gastroesophageal reflux disease and Barrett's esophagus.

Signs and symptoms

 Dysphagia (difficulty swallowing) is the first symptom in most patients. Odynophagia (painful swallowing) may be present. Fluids and soft foods are usually tolerated, while hard or bulky substances (such as bread or meat) cause much more difficulty. Substantial weight loss is characteristic as a result of poor nutrition and the active cancer. Pain, often of a burning nature, may be severe and worsened by swallowing, and can be spasmodic in character. An early sign may be an unusually husky or raspy voice.

 The presence of the tumor may disrupt normal peristalsis (the organised swallowing reflex), leading to nausea and vomiting, regurgitation of food, coughing and an increased risk of aspiration pneumonia. The tumor surface may be fragile and bleed, causing hematemesis (vomiting up blood). Compression of local structures occurs in advanced disease, leading to such problems as superior vena cava syndrome. Fistulas may develop between the esophagus and the trachea, increasing the pneumonia risk; this symptom is usually heralded by cough, fever or aspiration.

 If the disease has spread elsewhere, this may lead to symptoms related to this: liver metastasis could cause jaundice and ascites, lung metastasis could cause shortness of breath, pleural effusions, etc.

Causes and risk factors

 Increased risk

There are a number of risk factors for esophageal cancer. Some subtypes of cancer are linked to particular risk factors:

     * Age. Most patients are over 60, and the median in US patients is 67.

    * Gender. It is more common in men.

    * Tobacco smoking and heavy alcohol use increase the risk, and together appear to increase the risk more than these two individually.

    * Swallowing lye or other caustic substances.

    * Particular dietary substances, such as nitrosamine.

    * A medical history of other head and neck cancers increases the chance of developing a second cancer in the head and neck area, including esophageal cancer.

    * Plummer-Vinson syndrome (anemia and esophageal webbing)

    * Tylosis and Howel-Evans syndrome (hereditary thickening of the skin of the palms and soles).

    * Radiation therapy for other conditions in the mediastinum.

    * Celiac disease and primary biliary cirrhosis predispose toward squamous cell carcinomas

    * Gastroesophageal reflux disease (GERD) and its resultant Barrett's esophagus increase esophageal cancer risk due to the chronic irritation of the mucosal lining (adenocarcinoma is more common in this condition, while all other risk factors predispose more for squamous cell carcinoma). Giving that obesity predisposes to reflux, there appears to be an increased risk of adenocarinoma in obesity.

    * According to one Italian study of "diet surveys completed by 5,500 Italians" — a study which has raised debates questioning its claims among cancer researchers cited in news reports about it — eating pizza more than once a week appears "to be a favorable indicator of risk for digestive tract neoplasms in this population."

    * Recent epidemiologic studies have found that obesity (measured as BMI) is another strong risk factor for esophageal adenocarcinoma.

Decreased risk

     * Risk appears to be less in patients using aspirin or related drugs (NSAIDs).

    * The role of Helicobacter pylori in progression to esophageal adenocarcinoma is still uncertain, but, on the basis of population data, it may carry a protective effect. It is postulated that H. pylori prevents chronic gastritis, which is a risk factor for reflux, which in turn is a risk factor for esophageal adenocarcinoma.

    * According to the National Cancer Institute, "diets high in cruciferous (cabbage, broccoli, cauliflower) and green and yellow vegetables and fruits are associated with a decreased risk of esophageal cancer.”

Clinical evaluation

 Although an occlusive tumor may be suspected on a barium swallow or barium meal, the diagnosis is best made with esophagogastroduodenoscopy (EGD, endoscopy); this involves the passing of a flexible tube down the esophagus and visualising the wall. Biopsies taken of suspicious lesions are then examined histologically for signs of malignancy.

 Additional testing is usually performed to estimate the tumor stage. Computed tomography (CT) of the chest, abdomen and pelvis, can evaluate whether the cancer has spread to adjacent tissues or distant organs (especially liver and lymph nodes). The sensitivity of CT scan is limited by its ability to detect masses (e.g. enlarged lymph nodes or involved organs) generally larger than 1cm. FDG-PET (positron emission tomography) scan is also being used to estimate whether enlarged masses are metabolically active, indicating faster-growing cells that might be expected in cancer. Esophageal endoscopic ultrasound (EUS) can provide staging information regarding the level of tumor invasion, and possible spread to regional lymph nodes.

 The location of the tumor is generally measured by the distance from the teeth. The esophagus (25 cm or 10 inches long) is commonly divided into three parts for purposes of determining the location. Adenocarcinomas tend to occur distally and squamous cell carcinomas proximally, but the converse may also be the case.

Histopathology

 Most tumors of the esophagus are malignant. A very small proportion (under 10%) is leiomyoma (smooth muscle tumor) or gastrointestinal stromal tumor (GIST). Malignant tumors are generally adenocarcinomas, squamous cell carcinomas, and occasionally small-cell carcinomas. The latter share many properties with small-cell lung cancer, and are