Esophageal cancer is a type of malignant disease in which the uncontrollable growth of cells occurs in the tissues present in the esophagus. Esophageal cancer is a disease in transition to epidemiology. The cells in nearly any region of the body can take the form of cancer and can proliferate to other regions of the body. Esophageal cancer results when abnormal cells grow out of control in esophageal tissue. Eventually, the cells grow into a mass called a tumor.
The esophageal wall has various layers:
- Mucosa: Mucosa is a layer that lines the esophageal region’s inside. It has the following three portions:
The epithelium is said to be the innermost esophageal lining and normally comprises flat, thin cells known as the squamous cells. This is the portion where most cancers related to the esophagus start.
The lamina propria is a layer of connective tissue that is thin and it is right under the epithelium.
The muscularis mucosa is a layer of muscle that is also very thin and is present under the lamina propria.
- Submucosa: This layer of connective tissue just below the mucosa contains blood vessels and nerves. In some parts of the esophagus, this layer also includes glands that secrete mucus.
- Muscularis propria: This is the layer of muscle that is thick and is present under the submucosa. Its contraction occurs in a coordinated manner in order to push food downwards to the esophagus from the throat towards the stomach region.
- Adventitia: This layer of the esophagus is the outermost layer, and is made by connective tissue.
Esophageal cancer can grow anywhere along the whole length of the esophagus. It first grows in the inner layer of the esophagus wall and grows through the other layers in the outward direction. The structure of the esophagus can be described as the hollow, muscular passageway that moves food as well as liquid starting from the throat to the stomach. The wall of the esophagus is made up of several coverings of tissue, which include the mucous membrane, connective tissue, and muscle.
At the upper esophageal opening, there is a particular ring of muscle (which is known as the upper esophageal sphincter) that functions in relaxation in order to extend the esophagus when it feels the food or liquid coming toward it. When you swallow, food and liquids travel through the inside of the esophagus (called the lumen) to reach the stomach. The lower esophageal region which makes contact with the stomach region is called the Gastroesophageal (GE) junction. A particular ring of muscle near the gastroesophageal junction, known as the lower esophageal sphincter, is used to control the motion of food from the esophageal region into the stomach region.
The cancers which begin in the oesophageal area are much more common in the population of males than in females. The estimates of the American Cancer Society for esophageal cancer in the United States for the year 2022 are as follows:
- About 20,640 new cases of esophageal cancer were diagnosed (16,510 in males and 4,130 in females)
- About 16,410 deaths from esophageal cancer (13,250 in males and 3,160 in females)
The sixth most common cause of cancer deaths in the whole world is Esophageal cancer. There is variance in the rates of incidence within different geographic locations.
1Esophageal cancer Common Types
To know which type of esophageal cancer is present, it is important to know the type of cell that it starts in. This information helps the doctor decide which treatment is needed. (1)
The types of esophageal cancer are mainly divided into two, which are as follows:
- Squamous cell carcinoma:
The layer of the esophagus which is innermost (the mucosa) normally has a lining of squamous cells. Cancer that starts in these cells is known as squamous cell carcinoma. The squamous cell carcinoma begins in the cells that line the esophageal region. This type of cancer has some similarities with skin, lung, head, and neck cancer. In the United Kingdom, esophageal cancer is the second most common type. It has an association with smoking and alcohol intake. This type of cancer usually shows its effects in the upper and middle part of the esophagus, but can occur anywhere along the esophageal region.
This is also known as epidermoid carcinoma. However, the most common site of this type of cancer is the region of the neck (cervical esophagus) and in the upper two-thirds portion of the cavity of the chest (upper and middle esophagus of the thorax). Squamous cell carcinoma used to be the most common esophageal cancer type in the United States. However, this has changed over time, and now the percentage of this type of cancer is 30% in this country.
It can be developed in the tissue that is used to produce mucus that helps in the swallowing process. It is similar to the cancers of the stomach and the colorectal area. This type of cancer is the most common in the United Kingdom. It is estimated to be more common in males than in females and it is associated with being overweight and having a long history of past illness with acid reflux.
It is generally present in the lower region of the esophagus, near the stomach region. Glandular cells in the esophageal lining produce and release fluids such as mucus. Cancers that start in glandular cells are known as adenocarcinomas. Adenocarcinomas are often present in the lower one-third of the esophageal region (lower thoracic esophagus). In some conditions, such as Barrett’s esophagus, glandular cells start replacing the squamous cells in the lower portion of the esophagus, and this may lead to adenocarcinoma.
- Gastroesophageal (GE) junction tumors:
Adenocarcinomas which form at the region where the esophagus connects to the stomach (the GE junction, which includes about 5 cm of the stomach), behave like cancers in the esophagus, and are also treated like them.
The squamous cell carcinoma rates in the US have been decreasing, while adenocarcinoma rates have been increasing.
- Rare types of oesophageal cancer:
Treatment for rare types of oesophageal cancer differs and is dependent upon the type of cell cancer starts in.
Melanoma is said to be a type of skin cancer. It can rarely start in the esophagus.
Lymphoma is the cancer of the lymphatic system. Its treatment differs from other cancers of the esophagus.
Soft tissue sarcoma is the cancer of the supporting cells of the body, such as muscle or bone. Rarely, a sarcoma known as a gastrointestinal stromal tumor (GIST) may develop in the esophagus.