The prevalence of the process

Depending on the prevalence of the tumor, we can talk about different stages (stages of development) of bowel cancer.

The division follows certain standards, for which the scale is 3 main points:

• Depth of tumor infiltration (T)
• Node involvement (N)
• Presence of metastases (M)

Therefore, they use the name TNM - classification.

The numbers after the letters indicate the exact data on the extent of the tumor (T1-4), the number and location of the affected lymph nodes (N0-2) and the presence or absence of distant metastases (M0 and M1). T1 N0 M0 in this case means that we are talking about a small tumor of the innermost layer of the intestinal wall without damage to the lymph nodes and without metastases.

The following points are taken into account when dividing tumors into groups:

• the structure of the tumor tissue (degree of tumor differentiation). Here we are talking about the aggressiveness of the tumor. G1, G2, G3, G4 = good, moderate, poor, or undifferentiated malignant tissue
• operation radicality (R)

R0-resection = complete removal of the tumor within healthy tissue;
R1- resection = removal of the tumor along its edge, which means that the tumor grows to the borders of the tissue;
R2-resection = the tumor is not completely removed, visible remnants of the tumor remain in the patient's body.

An accurate assessment of the tumor by this criterion is possible only after surgery. It helps the doctor in planning further treatment.

For T (tumor) there are the following designations:

• TX = primary tumor that cannot yet be assessed
• T0 = no data for primary tumor
• Tis = Carcinoma in situ (tumor at a very early stage)
• T1 = primary tumor that has spread only to the innermost layer of the intestinal wall (Submucosa)
• T2 = primary tumor that has extended further into the muscular layer of the intestinal wall (Muscularis propria)
• T3 = primary tumor that extends through all layers of the intestinal wall including the subserosa layer (Subserosa) or even extends into the surrounding adipose tissue
• T4 = The tumor has spread to structures, organs in the immediate vicinity, or to the peritoneum
• T4a = The tumor passes through the visceral peritoneum (viscerales Peritonrum)
• T4b = Tumor directly affects other structures or organs

Notation for N (Nodi = nodes):

• NX = status of regional lymph nodes cannot be assessed
• N0 = no involvement of regional lymph nodes
• N1 = involvement of 1 to 3 nearby lymph nodes
• N1a = 1 lymph node affected
• N1b = 2 – 3 lymph nodes affected
• N1s = Tumor nodules or satellites in the subserosa (Subserosa) without involvement of regional lymph nodes
• N2 = affected by 4 or more nearby lymph nodes
• N2a = 4 - 6 lymph nodes affected
• N2b = 7 or more lymph nodes affected

For M (metastases) use the following division into groups:

• М0 = no data for distant metastases
• M1 = have distant metastases
• M1a = distant metastases in one organ
• M1b = distant metastases in multiple organs or in the peritoneum