Esophageal cancer overview

# Overview
Esophageal cancer is malignancy of the esophagus. There are two sub-types, squamous cell carcinoma and adenocarcinoma. Esophageal tumors usually lead to dysphagia, odynophagia, weight loss, and hematemesis and are diagnosed by carrying out a biopsy. Esophageal cancer must be differentiated from gastroesophageal reflux disease (GERD), Barrett's esophagus, esophageal achalasia, gastritis, gastric ulcer, and stomach cancer. Common risk factors in the development of esophageal cancer are smoking, alcohol, gastroesophageal reflux disease, and Barrett's esophagus. Small and localized tumors are treated with surgery, and advanced tumors are treated with chemotherapy, radiotherapy or a combination of both. Prognosis is fairly poor but depends on the extent of the disease and other medical problems.

# Classification
Esophageal cancer may be classified into squamous cell carcinoma or adenocarcinoma based on histology.

# Pathophysiology
The pathophysiology of esophageal cancer depends on the histological sub-type, whether squamous cell carcinoma or adenocarcinoma.

# Differential diagnosis
Esophageal cancer must be differentiated from gastroesophageal reflux disease (GERD), Barrett's esophagus, esophageal achalasia, gastritis, gastric ulcer, and stomach cancer.

# Epidemiology and Demographics
Esophageal cancer is the 6th leading cause of death from cancer and the 8th most common cancer in the world. The prevalence of esophageal cancer worldwide is about 3.5 per 100,000. In the United States, about 17,000 new cases are diagnosed every year, and 4.2 per 100,000 Americans has esophageal cancer. Esophageal cancer is mostly present in the "Asian belt" region which include China, Japan, India and Iran.

# Risk Factors
Common risk factors in the development of esophageal cancer are tobacco smoking, alcohol, gastroesophageal reflux disease, and Barrett's esophagus.

# Screening
Screening for esophageal cancer has not yet been established. Screening may be effective in reducing the incidence of esophageal adenocarcinoma, especially in Barrett's esophagus, but it is left at the physician's discretion.

# Natural History, Screening and Prognosis
The incidence of esophageal dysplasia turning malignant is very low, especially outside the United States. Complications of esophageal cancer include dysphagia, anemia, and tracheoesophageal fistula. This finding has caused some uncertainty as to the usefulness of screening. Esophageal cancer is associated with a 5 year survival rate of 20%.

# Diagnosis

## Diagnostic Study of Choice
Esophageal cancer is best diagnosed using an endoscope to visualize the esophageal lesion, followed by a biopsy to confirm the diagnosis. Endoscopic biopsy is done in a single visit at the hospital.

## Staging
According to the American Joint Committee on Cancer, there are 4 stages of esophageal cancer based on the tumor spread.

## History and Symptoms
Patient history in esophageal cancer includes pain in the throat or chest, regurgitation of food and hoarseness of voice. Symptoms of esophageal cancer include dysphagia, odynophagia, weight loss, and hematemesis. It should be noted that superficial esophageal cancer may have an insidious onset, so screening for Barrett's esophagus is important in this case to diagnose cancer earlier.

## Physical examination
Physical examination of patients with esophageal cancer is usually unremarkable, unless the disease has metastasized, in which case cervical lymphadenopathy and jaundice may be seen.

## Laboratory Findings
There are no diagnostic lab findings since diagnosis is based mainly on biopsy and esophageal endoscopy. However, routine tests are done to rule out anemia and metastases to the liver.

## CT
CT scans may be used for staging of esophageal cancer. Findings on a CT scan suggestive of esophageal cancer include eccentric or circumferential wall thickening, or peri-esophageal soft tissue and fat stranding.

## MRI
MRIs can be useful when used with positron emission tomography (PET) for staging esophageal cancer since it has greater soft tissue contrast than CT scans.

## Other Imaging Findings
Other imaging studies for esophageal cancer include positive emission tomography scanning with 18-fluorodeoxyglucose (FDG-PET). FDG-PET is a noninvasive staging modality that is more sensitive than CT or EUS for the detection of distant metastases.

## Other Diagnostic Studies
Laparoscopy, thoracoscopy and bronchoscopy can be used in addition to EUS and CT in locally advanced esophageal cancer to accurately diagnose and stage lymph node metastasis.

# Treatment

## Medical Therapy
The predominant therapy for esophageal cancer is surgical. Chemotherapy is used to treat advanced esophageal cancer. Chemotherapy can be used alone as monotherapy or in combination with radiotherapy or surgery. Chemotherapy may be used  as adjuvant therapy to shrink a tumor before being surgically resected or as neoadjuvant therapy after surgery to kill any cancerous cells that may have been left, and finally, in advanced tumors to shrink them or to relieve symptoms.

## Surgery
The predominant therapy for esophageal cancer is surgical resection by esophagectomy. The disease must be localized in order for it to be operable. Adjunctive chemotherapy and radiation may be required in more advanced cases of esophageal cancer, and to shrink down a localized tumor so that it may become operable.

## Primary Prevention
Effective measures for the primary prevention of esophageal cancer include the treatment of gastroesophageal reflux disease and Barrett's esophagus, weight loss, avoidance of tobacco and alcohol, and a diet rich in fruits and vegetables.

## Secondary Prevention
Secondary prevention may be effective in reducing the incidence of esophageal cancer, if treated early at the dysplasia stage with monoclonal antibody therapy. Presently, there is no particular program in place to reduce the incidence of esophageal cancer.