The most frequent question about cancer asked by a patient or his relative to the doctor is “At what stage is the cancer?”

The answer to this question is not always simple and it depends on which cancer you are talking about and which staging system the doctor is using. Some types of cancer have more than one type of staging system.

Most types of cancer have 4 stages, numbered 1 – 4. Often doctors write the stage down in roman numerals. So you may see stage 4 written down as stage IV.

Here is a brief summary of what the stages mean for most types of cancer.

  • Stage 1 usually means a cancer is relatively small and contained within the organ it started in.
  • Stage 2 usually means the cancer has not started to spread into surrounding tissue, but the tumour is larger than in stage 1. Sometimes stage 2 means that cancer cells have spread into lymph nodes close to the tumour. This depends on the particular type of cancer.
  • Stage 3 usually means the cancer is larger and may have started to spread into surrounding tissues and there are cancer cells in the lymph nodes in the area.
  • Stage 4 means the cancer has spread from where it started to another body organ. This is also called secondary or metastatic cancer.

What is staging?

Staging is a way of describing the size of a tumour and how far it has grown. When doctors first diagnose a cancer, they carry out tests to investigate the extent of the cancer locally and to see whether it has spread to another part of the body from where it started.

Why is staging important?

Staging is important because it usually tells the specialist which treatments you need. If a cancer is just in one place, then a local treatment such as surgery could be enough to get rid of it completely. A local treatment treats only one area of the body.

If a cancer has spread, then local treatment alone will not be enough. A ‘systemic’ treatment will be needed as well. Systemic means treating the whole body. Chemotherapy, hormone therapy and other drug treatments are systemic treatments because they circulate throughout the body in the bloodstream.

Sometimes doctors aren’t sure if a cancer has spread to another part of the body or not. They look at the lymph nodes near to the cancer. If there are cancer cells in these nodes, it is a sign that the cancer has begun to spread. Cancer doctors call this ‘positive lymph nodes’. The cells have broken away from the original tumour and got trapped in the lymph nodes. But we can’t always tell if they’ve got any further. In this situation, doctors usually suggest ‘adjuvant’ treatment. This means treatment alongside the treatment for the main primary tumour. The aim is to kill any cancer cells that have broken away from the primary tumour.

Staging systems

Staging systems are worked out for most types of cancer. The systems are there so that

  • Doctors have a common language to describe tumours
  • Treatment results can be accurately compared between research studies
  • Guidelines for treatment can be standardised between different treatment centres

Two main types of staging systems are used by doctors. The TNM system and number systems.

The ‘TNM’ staging system

‘TNM’ stands for Tumour, Node, Metastasis. This system can describe the size of a primary tumour, whether there are lymph nodes with cancer cells in them and whether the cancer has spread to a different part of the body. The system uses numbers to describe the cancer.

  • ‘T’ can be 1 to 4, with ‘1’ being a small tumour and ‘4’ a large one
  • ‘N’ can be 0 to 3, with ‘0’ meaning no positive lymph nodes and ‘3’ many positive nodes
  • ‘M’ is either 0 or 1, with ‘0’ meaning the cancer has not spread and ‘1’ meaning that it has spread

Sometimes the letters AB or C are used to further divide the number categories – for example, stage 3C cervical cancer.

P can be used before the letters TNM to mean a tumour that has been removed by surgery.

Number systems

These usually have a scale of 1 to 4 (or sometimes A to D). ‘1’ typically means a small tumour that has not spread and no positive lymph nodes. ‘4’ would mean that the cancer had spread to other major organs in the body.