Stages of Cancer

There are several different stages of cancer, which are ranked in order of severity. Slow-growing, non-aggressive or early-stage cancers are at the bottom of the scale, while fast-growing and metastatic cancers are at the top. All types of cancers can be ranked under a staging system.

Following a positive identification of cancer, doctors will try to establish the stage it is at. Staging cancer is important for several reasons. First of all, it provides a method of assessing the how advanced the cancer is, and provides a standard terminology for doctors and other health professionals to describe it. More importantly though, correct establishment of the stages of cancer is critical for developing a treatment program for the disease, with treatments being directly related to disease stage.

Therefore, incorrect staging can leads to the patient receiving an improper treatment, decreasing their chance of survival. Lastly, it has been shown that the stage at diagnosis can predict survival, which means it predicts very well what your prognosis will be. For some cancers such as ovarian cancer, it is a very powerful predictor of survival, so much so that most other prognostic factors are of little importance in comparison to stage.

One system used for assigning the stages of cancer is numbering the stages from zero to four. Stage zero is the least severe, while stage four is the most aggressive. Alternatively, the numbered staging system can be depicted in Roman numerals (I to IV). These can be divided further into substages such as stage IIIa or IIIb, where the characteristics of the cancer falls slightly in between the normal stages.

  • Stage 0 cancers are termed “in situ carcinoma,” which means there is no invasion of cancer cells into the normal surrounding tissue of the organ of origin
  • Stage I cancers are relatively small and contained within the organ they started in
  • Stage II cancers are larger than stage I cancers but have not spread into surrounding tissue
  • Stage III cancers are even larger still. It may have started spreading to the surrounding tissues and there are cancer cells in lymph nodes. Whether a cancer is designated as Stage II or Stage III can depend on the specific type of cancer.
  • Stage IV cancers have spread to other organs or throughout the body

Here is an example of what these stages look like for colon cancer:

In addition the the above system, there are others for classifying the stages of cancer. The TNM (Tumor, Node Metastasis) system ranks a cancer with three separate parameters: tumor size, lymph node involvement, and metastasis. Each of these criteria are separately listed and paired with a number to indicate its stage. For example, a T2N2M0 would be a cancer with a T2 tumor, N2 involvement of the lymph nodes and no metastasis (i.e. it hasn’t spread to other parts of the body).

  • T refers to the primary Tumor and can have a number of 0 to 4
  • N represents regional lymph node involvement and can also be ranked from 0 to 4
  • M is for metastasis, and is 0 if no metastasis has occurred, or 1 if metastases are present

This particular system is the one used to classify the stages of cancer for ovarian tumors. For cervical and ovarian cancers it is called the “FIGO” system, developed by the International Federation of Gynecology and Obstetrics, a non-governmental organization representing obstetricians and gynecologists. Each TNM stage has a corresponding FIGO stage. Read more detailed information on the stages of ovarian cancer here.

Here is a table showing how these TNM stages of cancer are correlated to the FIGO stages of ovarian cancer:

Seeking a second opinion when an individual is diagnosed with cancer can sometimes generate conflicting information. Doctors might sometimes disagree over the staging of a particular cancer. If the doctors you see do give different answers, it is a good idea to ask about why they disagree on their staging assessment, and how their treatment approaches might differ. Remember always to make sure you involve yourself with your treatment as much as possible.