The prevalence of the process

Gastric cancer most often arises from the glandular cells of the gastric mucosa. This is the layer of cells that lines the inner wall of the stomach.

As long as the tumor is still small, it is limited to this area. When its size becomes larger, it penetrates into the deep layers of the stomach wall, which means that the tumor affects the muscles of the stomach and peritoneum. With continued growth in depth, the tumor spreads to the surrounding lymph nodes. In this case, individual cells can separate and penetrate into the bloodstream and lymphatic vessels. With the flow of blood and lymph, cancer cells enter other organs. There they can linger and continue to breed; daughter tumors (metastases) occur. In stomach cancer, metastases most often appear in the peritoneum, in the liver, in the lymph nodes and in the lungs. But other organs can also be affected. When tumor cells become fixed in the peritoneum, it can lead to ascites (accumulation of fluid in the abdominal cavity).

Stages of development of stomach cancer

The stage of tumor spread is an important criterion in choosing the best suitable treatment for patients. Therefore, in order to more accurately characterize the tumor, the process, depending on its prevalence, is divided into various stages.

The classification is carried out according to certain categories, giving indicators mainly according to three criteria:

• tumor size (T)
• involvement in the process of lymph nodes (N)
• presence of metastases (M)

Hence the name TNM-classification is also used. The numbers behind the letters give an idea of the more precise size and extent of the tumor (T1-4), the number and position of affected lymph nodes (N0-3), and the presence or absence of distant metastases (M0 or M1). Accurate TNM staging is sometimes only possible after surgical removal of the tumor.

The next point that plays a role in the characterization of the tumor is the structure of the tumor tissue. It is determined by microscopic examination of the taken tissue and gives an idea of the degree of aggressiveness of the tumor. With the help of microscopic examination, it is possible to determine what type of stomach cancer is in question. There are fast-growing and less aggressive variants (diffuse type or intestinal).

Determining the spread of the tumor and the result of histological examination help the doctor in planning the stages of treatment.

In case of late detected tumor of the stomach, despite the first successful treatment of cancer, the resumption of the process may appear over the next years. This means that the swelling in the rest of the stomach, as well as in other areas of the body, may reappear (relapse).