Stomach cancer(gastric cancer) starts in the stomach. It is characterized by a growth of cancerous cells within the lining of the stomach. Gastric carcinoma tends to spread through the wall of the stomach and from there into the adjoining organs (pancreas and spleen) and lymph nodes. It can metastasize through the bloodstream and lymph system to distant organs such as the liver, bones, and lungs. However, It is difficult to detect this cancer because most people usually do not show any symptoms at the early stage. So for better understanding stomach cancer, it is useful to learn about the types and stages of this cancer.
Types of Stomach Cancer:
Adenocarcinoma
Most of the stomach cancers are adenocarcinomas. It is estimated that around 90% to 95% of gastric cancers are of this type. The cancer develops from the cells that form the mucosa, the innermost lining of the stomach.
Lymphoma
Around 4% of stomach cancers are of this type. These are cancers of the immune system tissue that are sometimes found in the wall of the stomach. Lymphatic tissue drains away fluid and helps fight infection. The treatment and outlook depend on the type of lymphoma.
Gastrointestinal stromal tumor (GIST)
These rare tumors start in very early forms of cells in the wall of the stomach called interstitial cells of Canal. Some of these tumors may be benign, others are cancerous. Although GISTs can be found in other parts of the digestive tract, most are found in the stomach.
Carcinoid tumor
These tumors start in the hormone-making cells of the stomach, usually in the digestive tract. This type of stomach cancer is rare. Most of these tumors do not spread to other organs. The tumors are discussed in more detail in Gastrointestinal Carcinoid Tumors.
Other types of very rare cancer of the stomach are including squamous cell carcinoma, leiomyosarcoma and small cell carcinoma.
Stages of Stomach Cancer:
The stages of gastric cancer tells you how big it is and how far it’s spread. It helps your doctor decide which treatment you need. There are normally 2 staging system: numbers system and TMN system.
In numbers system, the clinical stages of stomach cancer can be classified into Stage 0 to Stage IV. They are as follow:
Stage 0. It is the very early stage of stomach cancer, only limited to the inner lining of the stomach. It is difficult to diagnose at this stage. It can be treated by endoscopic mucosal resection(in routine screenings), or by gastrectomy and lymphadenectomy without need for chemotherapy or radiation.
Stage I. In this stage, the carcinoma has grown further than the lining of the stomach. It may have grown into the muscle wall and there may be cancer cells in the lymph nodes. It has not spread to other organs. In Stage 1A, it penetrates to the second or third layers of the stomach. In Stage 1B, it penetrates to the second layer and nearby lymph nodes. Stage 1A is treated by surgery, including removal of the omentum while Stage 1B may be treated with chemotherapy or radiation therapy.
Stage II. The carcinoma is still within the lining of the stomach. But it penetrates to the second layer and more distant lymph nodes, or the third layer and only nearby lymph nodes, or all four layers but not the lymph nodes. Treated as for Stage I, sometimes with additional neoadjuvant chemotherapy.
Stage III. It has penetrated to the third layer and more distant lymph nodes, or penetrates to the fourth layer and either nearby tissues or nearby or more distant lymph nodes. It can be treated as for Stage II and a cure is still possible in some cases.
Stage IV. In this stage, the carcinoma is advanced and has spread to body organs further away from the stomach such as the lungs, brain or bones. A cure is very rarely possible at this stage. Some other techniques to prolong life or improve symptoms are used including laser treatment, surgery, stents and medications.
The TNM staging system is also used. T describes the size of the original tumor. N tells whether the cancer has spread to your lymph nodes. M tells whether the cancer has metastasized to other parts of your body.