Esophagus is an important part of the digestive system, forming a bridge between the mouth and the stomach. It is about 25 cm long tube with flexible diameter; it continuously adapts to the passing food. The esophagus starts at the end of the pharynx in the neck and continues through the chest to the diaphragm and into the abdomen. In the abdomen, it is connected to the stomach. The main task of this tube is to transport swallowed food from the mouth to the stomach; the food is pushed through the tube by specific peristaltic movements. Esophageal cancer can affect this important organ without any preceding warning signals.
A tumour is a pathologic formation that results from changes in genetic material of cells. Natural behaviour of the cells is changed by this process, making the cells immortal and the formation constantly growing. By their nature, the tumours are divided into benign or malignant. Benign tumours grow slowly, do not affect the surroundings and metastases never appear. Metastases are secondary tumours that appear after time in different locations. Benign tumours may cause problems by exerting pressure on the surrounding organs and thus disrupting their function. Malignant tumours, on the contrary, grow very quickly, penetrate into the surrounding organs and destroy surrounding tissue. One of the very unpleasant attributes of malignant tumours is also metastasizing. A cancer is a disease caused by a malignant tumour; it is characterized by uncontrolled growth and proliferation of cells.
Types of Esophageal Cancer
Tumours of the esophagus can be divided into benign and malignant; the later mentioned represent the esophageal cancer.
Benign tumours are not aggressive; they do not affect the nearby structures and do not metastasize. In the esophagus, benign tumours usually arise from the cells of the inner layers of the esophageal wall. It can be tumours of connective tissue cells, called fibromas, tumours of fat tissue, called lipomas, and especially tumours of smooth muscle cells, called gastrointestinal stromal tumours (previously called leiomyomas). Benign tumours that protrude into the lumen of the esophagus are adenomas, papillomas, or myxomas. Most benign tumours remain without any symptoms until significant growth. The detection of these tumours happens usually incidentally, by X-ray or endoscopic examination of the upper digestive tract. At times, bleeding into the digestive system or swallowing problems may appear prior to diagnosis.
Malignant tumours of the esophagus, or esophageal cancer, are formed mostly from epithelial esophageal lining, these are called carcinomas. Less frequently, malignant tumours arising from other types of cells may appear, such as lymphomas growing from the lymph nodes or sarcomas growing from the muscle.
Histological Types of Esophageal Cancer
As mentioned above, esophageal cancer is a malignant tumour of the esophagus. The most frequent type, carcinoma, can be divided into squamous cell carcinoma and adenocarcinoma according to histological structure.
Squamous cell carcinomas are the most common type of esophageal cancer in the world. Among the risk factors for developing squamous cell carcinoma are smoking, alcohol consumption, and consuming hot and spicy food.
Adenocarcinomas, on the other hand, are the most rapidly growing group of esophageal cancer. Their development is closely connected to the gastroesophageal reflux disease. Usually, it develops from a disease called Barrett's esophagus, in which changes in the inner lining of the lower esophagus appear due to inflammation caused by repeated irritation of the the esophagus by leaking gastric juices.
Symptoms of Esophageal Cancer
No symptoms of esophageal cancer are present at the beginning of the disease; most cases are therefore diagnosed at an advanced stage. Esophageal cancer usually causes problems first when about 2/3 of the lumen of the esophagus is filled with tumour masses. The symptoms include dysphagia, painful swallowing, weight loss, and regurgitation. In addition, there usually are burning pain behind the breastbone, nausea, weakness and difficult breathing. Unfortunately, all these symptoms are non-specific; they can also occur in other diseases, such as heart attack or inflammation of the esophagus.
Diagnosis of Esophageal Cancer
To diagnose esophageal cancer, mainly endoscopic examination is used. The examination is performed by a flexible tube device with a camera and light source on the end that is inserted through the mouth into the esophagus. Any changes in the lining of the esophagus can be observed; small samples of tissue from the affected area can be collected for histological examination if necessary. Due to the fact that malignant tumours tend to penetrate into the surrounding structures, it is necessary to use also ultrasound or CT scan to determine the extent of the tumour and the degree of impairment of the surroundings. CT scan is used also to detect any metastases within the body. Unfortunately, early metastasizing through the lymph circulation is typical for esophageal cancer.
Treatment of Esophageal Cancer
Smaller benign tumours of the esophageal mucosa can be easily removed endoscopically. If the tumour is bigger, surgery is required. Surgical treatment is also the only way how to treat esophageal cancer. However, it is only successful in individuals without metastases and in good overall condition. During the surgery, the affected part of the esophagus with surrounding lymph nodes is removed. In adenocarcinomas, so-called adjuvant chemotherapy is used prior to the surgery. It causes reduction of the tumour mass and therefore makes the removal of the affected area easier. Its effect is similar to the effect of radiotherapy in squamous cell carcinoma. Radiotherapy is a procedure during which primarily the affected cells are exposed to ionizing radiation. Unfortunately, the surgery is possible in less than 50% of diagnosed cases of esophageal cancer; the rest is diagnosed too late. The most important part of esophageal cancer treatment is, therefore, its early detection.