Stages of Cancer

Stages of Cancer

The stage of the cancer refers to how large the tumour is and how much the cancer has spread. Usually, the doctor will provide you with this information at the time of diagnosis. Knowing which stage the cancer is at helps doctors decide what course of treatment needs to be followed. It also helps them predict how successful the treatment is likely to be. 

Cancer staging may also include grading the cancer. This refers to checking how similar the affected cells are to normal cells. This information will also influence the course of treatment. 

Doctors use diagnostic tests or a histopathology report to identify the stage of cancer.

Why staging?

When a doctor assesses your case, it is imperative for them to know the tumour’s size and the extent to which it has spread to local and distant organs. This can help them choose the appropriate treatment option for your case. Treatment options may differ in different stages, for instance, treatment option for early stage cancer is usually surgery or radiation and when at advanced stages, chemotherapy may be recommended. Staging also helps the doctor to determine the course or the duration of the treatment. 

Staging, on a larger scale also help the researchers and scientists group their study with a particular stage. Making the assessments easier, outcomes more measurable and efficient, especially in this field of Oncology where faster, safer and reliable treatment options are the need of the hour.

How does cancer spread?

The size of the tumour and the extent to which it has spread determines the stage of the cancer. The routes of metastasis is analysed to understand how the cancer spreads. Those are –

Local – Cancers can spread locally by moving to the nearby healthy tissue. 

Hematogenous – Spread of cancer through the body’s circulatory system, where the cancer spreads through the blood vessels. Favoured by sarcomas 

Lymphatic – Spread of cancer through the body’s lymphatic system, whose primary function is to transport lymph (a fluid containing infection-fighting White Blood Cells) throughout the body. This is favoured by most Carcinomas. 

Transcoelomic – This is the spread of cancer via the body cavities. The cancer cells enter peritoneal (spaces of the digestive tract and abdominal organs), pleural (spaces of the lungs), pericardial (the heart) or subarachnoid (the brain) spaces.

How is staging done?

There are a number of exams and tests used by doctors to confirm the stage that the cancer is in. Physical examination may detect cancer to an extent, for instance, head and neck cancers. Imaging tests like PET scans, CT scans and x-rays are also used to see the site and complexity of tumor, whether local or metastasised. And based on the reports of these imaging tests, a biopsy would confirm the diagnosis.

Staging is done when a person is first diagnosed, before the treatment begins. There can be two types of staging, which are

Clinical staging – Depending on the results from the physical exams, imaging tests, the doctor estimates the extent to which the cancer has spread. 

Pathologic staging – The doctor determines the pathologic stage of a patient after looking into the histopathology report after surgery.

Types of staging systems

There are two different types of staging systems followed by doctors. One is the TNM (primary tumour, regional node, metastasis) system, and the other is the numerical system. 

The TNM system uses a combination of letters and numbers to show the stage of cancer. It measures three aspects of the cancer:

  1. T: This refers to the size of the tumour at the original site of cancer. It can be 0, 1, 2, 3 or 4. Here 1 refers to small and 4 refers to large.
  2. N: This refers to the spread of cancer to the lymph nodes. It can be between 0 to 3, with 0 referring to no presence of cancer in the lymph nodes and 3 referring to a lot of lymph nodes showing the presence of cancer.
  3. M: This refers to metastasis or the spread of the cancer from the original site to other parts of the body. This is measured in 0 or 1. 0 indicates that the cancer has not been found in any other part of the body. 1 indicates that the cancer has spread to other parts of the body.

For example, if the diagnosis shows a TNM stage of T4N1M0, then it means that the original tumour is large in size, cancer has been found in a few of the surrounding lymph nodes, but it has not spread to other parts of the body.

The number system of stages, uses roman numerals from 0 to IV.

Stage 0: In this stage, there is no tumour.

Stage I: In this stage the cancer is relatively small and is contained within the organ that it originated in. This is also called the early stage of cancer.

Stage II: In this stage, the growth of the tumour is more than stage 1. In some types of cancer, the cancer at this stage has not spread to the surrounding lymph nodes. In some other types of cancer, this stage suggests that the cancer has spread to a few of the surrounding lymph nodes.

Stage III: This stage usually suggests that the cancer has grown and has also spread to the surrounding lymph nodes.

Stage IV: At this stage, the cancer has spread to other parts of the body. This is also called secondary or metastatic cancer.