Determining disease stage

Stage indicates the extent of spread of malignant disease, and its determination helps in understanding the disease progression, predicting patient survival, planning optimal treatment, and finding potential clinical trials in which the patient could be included. To determine the stage of the disease, it is necessary to perform diagnostic work-up (you can read about diagnostics in a separate article). There are several systems for determining the stage of the disease, and the most widely used is the TNM system. Most systems provide information about the location of the tumor, the type of cells (you can read about types of cancer in a separate article), the size of the tumor, the spread to lymph nodes and distant parts of the body, and the grade of the tumor (indicates the extent to which the tumor cells differ from normal ones, which indicates the degree of aggressiveness of the disease).

TNM system. Most oncologists use the TNM system, and it is regularly written in the pathology reports after surgery for a tumor mass. T indicates the size and spread of the primary tumor into the surrounding tissue. N indicates the status (number) of lymph nodes around the primary tumor that are affected by tumor cells. The M status determines whether the tumor has spread to distant parts of the body (including lymph nodes not near the primary tumor). When the disease is classified according to TNM, each of these three categories is given a number that describes the disease in more detail - for example, T3N2M0. The meaning of these numbers is as follows.​

Figure 1. T classification for bladder cancer. While in T1 the tumor is present on the inner lining of the bladder, in T4 the tumor has completely penetrated the wall and is spreading into the surrounding tissue.

Primary tumor (T)

TX: The primary tumor cannot be adequately determined.

T0: The primary tumor cannot be found.

T1, T2, T3, T4: Indicates the size and extent of the primary tumor into surrounding tissue. The larger the number next to T, the larger the tumor or the greater the infiltration of surrounding tissue. Sometimes there are additional divisions of the T stage to show more detail, such as T2a and T2b.

Regional lymph nodes (N)

NX: Cancer in regional lymph nodes cannot be adequately determined.

N0: No involvement of regional lymph nodes by the tumor.

N1, N2, N3: Indicates the number and location of regional lymph nodes that are affected by the tumor. The higher the number next to N, the more lymph nodes are affected by the disease.

​Distant metastases (M)

MX: The presence of metastases cannot be adequately assessed.

M0: No distant metastases.

M1: Metastases are present (spread to distant parts of the body).

​Stage of the disease. Based on the TNM classification, the disease can be simply classified into one of five stages of the disease.

• Stage 0: Abnormal cells are present but without spreading to surrounding tissue, so-called carcinoma in situ (CIS). It should be noted that CIS does not indicate cancer, but it can progress to cancer.

• Stage I, II and III: Cancer is present, and the higher the stage, the more advanced the disease (larger tumor and more significant spread to surrounding tissue). For many tumors, stage III indicates when the disease has spread to regional lymph nodes (N1-3).

• Stage IV: Indicates the spread of the disease to distant parts of the body (metastases).

Additional interesting facts

What is the FIGO classification? Although most malignant tumors today are divided into stages using the TNM classification, in gynecological tumors such as ovarian and uterine cancer, the so-called FIGO classification (abbreviation of the world gynecological society Federation Internationale de Gynecologie et d'Obstetrique), although these diseases can also be classified by the TNM classification. The FIGO classification also divides these tumors into 4 stages.​​

Continue reading:

Prognosis - can cancer be cured?

Need more information about this topic? Contact us.