What Is Stage 3 Cancer?

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Cancer involves the fast growth of abnormal cells, which divide and multiply into masses and spread into different areas of the body. When assessing the severity of cancer, doctors will ‘stage’ the cancer. Factors that determine the stage include the location of the mass or tumour, how big it is, and how far it has spread. Stage 3 cancers are advanced and therefore may require more intensive treatment, however, they are not as concerning as stage 4.

What Is Cancer Staging?

Staging is a grouping or categorising process that is done after a cancer diagnosis, before treatment begins. Staging describes the cancer in terms of its progression and location, information for which your doctor may need to do further assessments such as imaging and lab tests. Cancer is generally referred to by the stage allocated at diagnosis, regardless of changes over time (although new information could be added to the original stage).

There are many methods and systems for staging. One of the most common ways to stage cancer is using the TNM system, which uses a combination of numbers and letters in various ways depending on the type of cancer. The three basic categories assessed are:

Tumour (T) 

The size and extent of the primary tumour (where the cancer started). Usually described by a number between 1-4.

Nodes (N)

Lymph nodes near the primary tumour that have cancer. Usually described by a number between 0-3 (0 meaning none of the nodes are positive for cancer, 3 indicating that many are). Lymph nodes are small immune cell collections, often the first place that a nearby cancer will spread to before branching out to other parts of the body.

Metastasis (M)

Metastasis refers to how far the cancer has spread from the primary tumour to other parts of the body. It is usually described by the number 0 or 1 (0 indicating no spread). 

Number Staging For Cancer Explained

Number staging is the system referred to when we use the phrase ‘stage 3’. While the TNM system gives important details, the combinations can be grouped into broader categories as described below. 

  • Stage 1 (I) - Generally indicates that the cancer is small and contained within the organ where it started (no spread).
  • Stage 2 (II) - Generally indicates a larger tumour (compared to stage 1), but the cancer has not spread into the surrounding tissue. However, depending on the type of cancer, Stage 2 could also refer to cancerous cells that have spread to the nearby lymph nodes.
  • Stage 3 (III) - Generally indicates a larger cancer, possibly one which has spread into nearby lymph nodes as well as surrounding tissues.
  • Stage 4 (IV) - Also called secondary, advanced, or metastatic cancer. Generally indicates that the cancer has spread from where it began to at least one other organ.
  • Stage 0 - Some cancers have the option of a stage 0. This stage indicates that abnormal cells are present, but have not spread from the layer of cells where they started.

There is another staging system used to group all types of cancer into main categories, which is used more often by registries. This system refers to a cancer as in situ (abnormal cells present, however they haven’t spread to nearby tissue), localised (no sign of spread, cancer remains where it started), regional (cancer has spread to nearby lymph nodes, tissues, or organs), distant (cancer has spread to an outlying body part), or unknown (not enough information to allocate a stage).

The staging process can involve more or less categories than described here, or use systems in different ways depending on cancer details. Some cancers are graded instead of staged (e.g. brain cancer). The grade refers to the appearance of the cancer cell in comparison to normal tissue. If the cancer cells are very unusual, it could indicate quick growth. 

What Does Stage 3 Mean?

As mentioned above, stage 3 cancer usually indicates that the tumour is fairly large, and may have spread into nearby lymph nodes and surrounding tissues, but not to distant organs (locally advanced). However, each cancer type could be staged differently and a stage 3 categorisation for one cancer may not communicate the same information as stage 3 for another cancer. Below are some common cancer types, and examples of what a stage 3 allocation may mean for each:

Breast Cancer 

Cancer may have spread to lymph nodes or chest tissue near the breast. The tumour might be quite large at this point.

Lung Cancer

Cancer has spread to nearby lymph nodes, and could also have spread to nearby organs (heart, trachea, oesophagus). 

Prostate Cancer

Cancer has spread to nearby tissues, and may have reached the seminal vesicles. 

Colorectal Cancer

Cancer has spread into the wall of the intestine, possibly even into the muscle. It may also have grown into nearby lymph nodes and/or organs. 


Cancer has spread to nearby lymph nodes.

What Is The Prognosis For Stage 3 Cancer?

A prognosis is a prediction of how your cancer is likely to develop, the effects it will have, and how treatment may go for you. A prognosis speaks to the seriousness of the disease and chances of survival. Your doctor will use statistics and research in order to estimate a prognosis, along with your general medical information and details of your cancer (such as stage and grade). 

Statistics such as survival rates, which are established from research on groups of people with the same type of cancer, are useful in determining prognosis. Prognosis depends on the type of cancer, but broadly speaking stage 3 cancers have a shorter life expectancy and poorer survival rate than stage 2 cancers.

How Is Stage 3 Cancer Treated?

There are many different types of treatment for cancer, each with its own advantages and disadvantages. While no two people will respond exactly the same way to treatment, the information used to diagnose and stage the cancer helps your doctor to make predictions and plan the best course of treatment.  

Your stage 3 cancer could be addressed with common treatments such as surgery, chemotherapy, radiation, or a combination. If these are not appropriate for you, you might receive hormone therapy or immunotherapy instead. Treatment options for common cancers could include the following:

Breast Cancer 

The first step is usually chemotherapy or surgery. If the tumour can’t be shrunk enough to perform breast-conserving surgery, a mastectomy (full removal of the breast) may be needed. If the cancer is HER2 positive, targeted drug treatment before surgery may be required. After surgery, radiation, chemotherapy and/or targeted drugs may be administered. If your breast cancer is an inflammatory type, treatment could be slightly different. For women who are postmenopausal, bisphosphonates could be administered to reduce the risk of cancer spreading to your bones.

Lung Cancer

Treatment depends on the size of the tumour and affected lymph nodes. Usually, chemotherapy and/or radiation are used to start, followed by surgery if successful cancer removal is likely. More chemotherapy or radiation could be done after surgery.

Prostate Cancer

Treatment is usually hormone or radiation therapy, however, surgery beforehand may also be an option. Clinical trials might also be available.

Colorectal Cancer

Surgery is usually the treatment option for colon cancer in this stage, followed by chemotherapy. Stage 3 rectal cancer is usually the opposite, beginning with chemoradiation (combined chemotherapy and radiation), then surgery, and possibly another course of chemotherapy sometime later.


Surgery is usually the first treatment option, followed by radiation, targeted therapy, or immunotherapy. Sometimes surgery is not an option, in which case you would skip to the second step.


Navigating a cancer diagnosis and making treatment decisions can be overwhelming. Speak to a medical team about what your diagnosis, stage, and grade could mean, and what treatment options might be suitable for your unique goals, health status, and finances.

Staging helps your medical team decide on the initial best course of action, or which treatments are needed. The treatment that would be the best fit will depend on the size, location, spread, and more.

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