One of the first things you’ll have to know when you are diagnosed with cancer is its stage. In literature and movies, you might have seen characters deal with stage 4 cancer. The “stage” is a label doctors use to describe the size of solid tumors, like lung, bowel, and breast cancers. It also reveals how far the illness has spread at the time of diagnosis. Blood cancers, such as myelodysplasia or leukemia, behave differently and are categorized in different ways.
What is cancer staging?
This is the process of measuring the extent of cancer and identifying which organs it has affected. Doctors use cancer staging to easily describe the spread and size of cancer. More importantly, it helps to:
- plan treatment
- predict how well the therapy will work
- predict a patient’s outlook, the chance of recovery or the course of the disease (called a prognosis)
- choose an appropriate clinical trial, if the patient wants to join one
- create groups of people to compare and study in clinical trials
How are cancers categorized in these stages?
Oncologists use tests to determine the stage of cancer. These show the location of cancer and approximately how much is in the body. To know the stage, a physical exam, biopsy, blood test, an imaging test, or a combination of these may be required. They may also check the affected tissue during surgery or after the tissue is extracted during the procedure.
What systems do doctors use to stage cancer?
There are various staging systems for different cancers, but they generally follow either the:
- TNM system
- Numbered cancer stage system
What is the TNM system?
The TNM stands for tumor, node, and metastasis. Each of these categories is given a score, and together these numbers show how far the disease has grown. The TNM system stages most solid tumor cancers that form lumps, like prostate or breast cancer.
T – This part describes the size of the primary tumor. It also reveals if the tumor has grown into other tissues or parts of the affected organ. T is usually given as a number from 1 to 4. A lower number means that the tumor is smaller. It may also indicate that the disease has developed deeper into the organ or has spread to nearby tissues.
N – This specifies whether the disease has reached the lymph nodes around the site. Doctors use N0 to label cancer that hasn’t multiplied to any distant lymph nodes. N1, N2, or N3 means the disease has metastasized. These three categories can also note how many lymph nodes contain cancer as well as their location and size.
M – Metastasis indicates when the disease has infected other parts of the body through the lymphatic system or the blood. M0 means that cancer remains at its primary site and has not targeted a distant organ. Meanwhile, M1 means that you’re positive of cancer metastasis.
What is the numbered system?
This system uses stage numbers to know how far cancer has spread. Stages 1 to 4 are usually shown as the Roman numerals I, II, III, and IV. Generally, the higher the number, the graver the situation. Sometimes these categories are subdivided using letters A, B, and C. For most types of cancer, the stages mean the following:
Stage 0 – Cancer at stage 0 is often called “in-situ,” meaning the cancer cells remain at its original site. They also haven’t spread at all.
Stage 1 – This refers to cancer that is small and is only starting to get to nearby tissues. It has not spread to any lymph nodes or other organs.
Stage 2 and 3 – This indicates that the tumor is larger or has spread outside of its main site. This is where the malignant cells have taken over nearby tissues or lymph nodes.
Stage 4 – Immediate expert care is crucial for patients diagnosed with stage 4 cancer. Also known as metastatic or advanced cancer, stage 4 cancer means that the disease has traveled through the lymphatic system or blood to a distant site in the body.
What are the factors considered when staging?
The TNM description specify information about what tissues in an organ have cancer and how big the size of the tumor. It also reveals whether malignant cells have taken over other body parts. Other factors that are used to identify the stage for certain types of diseases include:
- tumor marker levels (such as PSA in men with prostate cancer)
- cancer cell type (such as squamous cells carcinoma or adenocarcinoma)
- genetic information of the disease (such as which genes are mutated)
Do the stages change?
Once the doctor diagnoses a person’s cancer stage (either the pathological or clinical stage), the category doesn’t change. If a stage 2 disease comes back after it is treated, it remains stage 2 cancer that has recurred. If the tumor cells spread to a distant part of the body after it is treated, it becomes metastatic stage 2. Learning about this is important because the stage at diagnosis is used to research treatments and survival statistics for specific stages of cancer.
What is restaging?
This process helps physicians plan further therapy when the disease comes back or gets worse after the initial treatment. Restating doesn’t mean that a stage 1 cancer becomes a stage 2. The stage of cancer remains the same. However, a tumor initially labeled as a T2 may be described as a T3 or T4 if cancer has reached nearby tissues or grown larger. Patients may test for this after treatment. When doing a restaging, it is shown with a lowercase “R” before the letters TNM on a medical report.
It’s important to get involved and be informed when making decisions about your care. Since various types of cancers develop differently, categorizing them according to size and metastasis helps your healthcare team look for appropriate treatment options. Ultimately, it will help you understand how serious your cancer is so you can develop the right course of action to get rid of it completely.