What is the stage of cancer?
When your doctor mentions the stage of cancer, it basically means the state of development, condition, or severity of the disease. It also indicates to what extent cancer has progressed or how much the cancer cells have spread. There are different stages of cancer and each stage of cancer has a story to tell about the condition of this disease.
Doctors often carry out diagnostic tests and it is only after all test reports arrive, can they determine cancer’s stage. The stages are labeled I to IV, with IV being the most severe and advanced. The particular stage tells the doctor about the prognosis and survival rate of the case.
Importance of cancer staging – Why is it done?
Staging of cancer is very important for your oncologist or cancer specialist because it helps to:
- Determine the type of treatment for the particular case
- Evaluate the prognosis with treatment
- Predict the possibility of a recurrence
- Predict the survival and death rate
- Bring about global benefit in collecting information on cancer statistics for better research.
The correct staging is, therefore, important because incorrect staging will lead to incorrect treatment. There are different types of staging systems used for different cancers.
How stage of cancer is determined?
The cancer stages are arrived at after careful examination of the cancer patient. Just signs and symptoms are not enough to confirm the stage. A thorough investigation is necessary which includes:
- Clinical examination methods, wherein after a thorough physical examination of the patient, the doctor determines the location and size of the malignant tumor and feels for any enlarged lymph nodes in the body.
- Pathological investigation of blood, stools, urine, and body fluids to look for any increased or decreased levels that may indicate malignancy.
- Radiological studies such as X-rays, CT scans, MRIs, and PET scans will show the location and size of the malignant tumor and also the presence of metastasis if any.
- The surgical investigation includes a surgical biopsy. The biopsy sample is examined in pathology for any malignant signs. A surgical report prepared during surgery mentions, confirms or reports any changes in the size of the tumor and on its spread.
Systems of staging cancer
There are different ways to stage the different types of cancers. According to the National Cancer Institute (NCI), the common fundamentals considered in staging cancer are:
- Where is the site of the primary tumor?
- What is its size and how many tumors are there?
- Has cancer spread to the lymph nodes?
- What are the cell type and tumor grade (how different are they from the normal cells)
- Is there any metastasis?
The two most commonly used staging systems are:
- The TNM staging system is used to stage most solid tumors
- The Roman Numeral System or overall staging system is used by some on most types of cancers.
1. TNM system of staging cancer
TNM staging of cancer is usually used to stage solid malignant tumors. Most tumors are classified by this system but some like brain tumors are not.
The TNM system is the most widely used and globally recognized standard for classifying cancer. Most hospitals and medical centers use this system for staging cancer case.
TNM staging of cancer was developed by a nongovernmental body called UICC or International Union Against Cancer with the purpose to bring about a global consensus to stage cancers and access their spread.
This purpose has been achieved and the TNM system is globally used. This also helped to bring about a coordinated global effort in cancer research. The UICC cancer staging has the same definitions as the AJCC (American Joint Committee on Cancer) cancer staging.
- The letter “T” stands for Tumor. “T” with a number (0 to 4) indicates the size and position of the tumor. It tells you how much the tumor has invaded into neighboring tissues. The size of the tumor is measured in centimeters (cm). A larger tumor or a tumor that has spread into the surrounding tissue receives a higher number.
- “N” stands for the Node of the lymphatic system. The letter “N” stands for lymph nodes. It accompanies a number, which tells you the spread of cancer to the lymph nodes, whether nearby or distant. Lymph nodes near the cancer site are called regional lymph nodes. Lymph nodes in further parts of the body are called distant lymph nodes. The more there are lymph nodes involved, the larger the number assigned.
- The letter “M” stands for metastasis (spread of cancer) and indicates whether cancer has spread or not. If it has not spread, it is labeled as M0. If it has spread, it is considered M1.
- The letter “X” indicates that the state of particular cancer cannot be determined. This may be because the diagnostic tests have not been done or that the results are not clear. For example, NX means that it is not possible to determine the stage of cancer and whether the tumor is localized or has spread to the lymph nodes or elsewhere.
Numbers are suffixed after the letters T, N, and M to indicate the progress of cancer. An ‘X’ suffixed after T or N or M simply means cancer has yet to be assessed or evaluated and therefore no staging has been done yet.
T – Tumor: 1 to 4 are suffixed after ‘T’ to indicate the size of the tumor.
- A “T1” will mean a smaller-sized tumor while
- A T4 will indicate a larger-sized tumor
N – Node: Similarly, 0 to 3 are suffixed after ‘N’ to indicate extent of spread of malignancy to the lymph nodes.
- N0 will indicate that there has been no spread or metastasis of malignancy to the lymph node.
- N1 will mean spread to the local regional lymph node.
- N3 will mean more involvement to the distal and more numerous lymph nodes.
- N2 gives the metastasis involvement between N1 and N3.
M – Metastasis: The numbers 0 and 1 are used after M to indicate metastasis to other distant organs.
- M0 means no metastasis and
- M1 will indicate that the malignancy has spread from the primary site to distant organs. This is the final stage of cancer.
2. The 5 Cancer Stages by Roman Numeral Staging System
A more simplified system stages cancer using roman numbers 0 to IV – the higher the number the more progressive the cancer is. This system of cancer staging uses 5 cancer stages and can give an idea to the doctor of the survival chances of the cancer patient. For example:
- Cancer of stage 0 will mean a localized early stage of cancer, wherein cancer cells have begun to form, they are localized to one tissue or part, have not invaded to the neighboring tissues and possibly the tumor is yet to form. This is called cancer in situ.
- Stage I cancer will indicate that the cancer is still small and contained in the organ of origin. Generally, stage 1 cancer patients have a 5-year survival of over 90%.
- Stage II cancer is bigger than stage I but has not invaded the neighboring tissues. However, there may or may not be some involvement of the local lymph nodes.
- Stage III cancer is larger than stage II cancer and has spread to the local and distal lymph nodes.
- Stage IV cancer indicates that cancer has spread or metastasized to the distal organs. This is the last stage of cancer. As a thumb rule cancers of stage 4 that have spread cannot be treated and are unlikely to survive for long. However, treatment can help to shrink or control them.
NCBI describes the the relation between this system of staging and the TNM classification.
- Cancer staging has been evolved to give the doctor an idea of the cancer he is dealing with.
- There are various stages of cancer.
- The stage is determined through complex tests.
- Most cancers have 4 Stages, which tell the doctor the severity and spread of malignancy to help him determine the line of treatment. Some cancers also have stage 0, which describes cancer in situ.