Understanding Stage 4 Colorectal Cancer

Staging Provides Us a Road Map, Not Hard-And-Fast Rules

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There are five stages of colorectal cancer, ranging from stage 0 to stage 4, which are meant to tell us whether and/or how far a malignancy has spread. Stage 4 is the most advanced stage, meaning that the cancer has spread (metastasized) beyond the colon or rectum to other organs such as the lungs or liver.

While stage 4 cancer certainly sounds scary, suggesting a disease that is terminal and out of control, is that what it actually means?

And, more importantly, how does the term apply to colorectal cancer specifically?

Categories of Stage 4 Colorectal Cancer

Stage 4 colorectal cancer is essentially a designation. While it tell us that the cancer has definitely advanced, it doesn't tell us how far or how big the tumors may or may not be.

For this, we use the so-called TNM system which assesses factor such as tumor growth (T), lymph node involvement (N), and metastasis (M). The system is pretty easy to decipher as it is governed by one simple rule: the higher the number or letter, the more advanced the disease.

In terms of metastasis (M), we classify it as one of two things:

  • M1a, meaning that the cancer has spread to one organ
  • M1b, meaning that the cancer has spread to more than one organ

While M1b would certainly seem the worst option, it's important to note that neither M1a nor M1b tells us two important things: whether the original tumor had grown through the walls of the colon or rectum, or whether lymph nodes have been affected or not.

Classifying Tumor and Lymph Node Involvement

Both tumor and lymph node involvement are important in helping us assess the likely outcome (prognosis) of the disease and what treatment options may be available to us.

Tumor classifications delineate to how far the original tumor extends, if at all, beyond the colon or rectum.

By contrast, lymph nodes (one of the filtration systems of our blood stream) tell us how extensively the cancer may or may not have spread.

In terms of the original tumor (T), we describe growth in a range of T1 to T4:

  • T1 means that the tumor has penetrated the mucosal layer of the colon or rectum but not the muscle.
  • T2 means that the tumor has penetrated the mucosal layer and extends to the outer muscle layer.
  • T3 means that it now extends beyond the muscle to the outermost layer but has not penetrated it.
  • T4a means that it has penetrated the colon or rectum but has not invaded nearby tissues or organs.
  • T4b means that it has penetrated the colon or rectum and has invaded nearby tissues or organs.

In terms of lymph node involvement (N), we classify this by a range of between N0 and N3:

  • N0 means no cancer in nearby lymph nodes.
  • N1 means cancer is either in one nearby lymph node (N1a), two to three nearby lymph nodes (N1b), or no nearby lymph nodes but rather in the surrounding fat cells (N1c).
  • N2 means that cancer in either in four to six nearby lymph nodes (N2a) or seven or more nearby lymph nodes (N2b).

Grading Stage 4 Colorectal Cancer

Once your oncologist is able to group all of these various classifications — the "T," the "N," and the "M" — he or she can the stage the disease.

In terms of stage 4 colorectal cancer, this leaves us with one of two options:

  • Stage 4a means that the cancer has spread from the colon or rectum to one other organ or a distant set of lymph nodes.
  • Stage 4b means that the cancer has spread to more than one other organ, a distant set of lymph nodes, or the lining of the abdominal cavity.

The Road Map After Staging

While staging provides us a lot of information, it still doesn't mean one thing and one thing alone. It doesn't, for example, tell us how large the original tumor was — if it was the size of an olive or the size of a grapefruit. It also shouldn't suggest that having seven affected lymph nodes is imminently worse than four.

Ultimately, each case is different, and staging only provides us a general road map by which sketch the way forward. Think of it as having a compass that points us in the right direction.

Depending on your individual factors, stage 4 colorectal cancer may involve a surgical resection (cutting out the area of cancerous colon and reattaching the healthy ends). Chemotherapy and/or radiation are also common depending on the extent of lymph node involvement.

Insofar as life expectancy is concerned, a lot of things can influence survival rates. Tumor location, tumor size, a person's age, general health, and even things like access to healthcare and individual attitude play a part in determining how long a person can survive.

Typically speaking, a person with stage 4 colorectal cancer has roughly a one in seven chance of surviving past five years, with some far exceeding this figure. What this tell us is that stage 4 cancer, however distressing, cannot be considered a death sentence. Ultimately, the one factor that differentiates your cancer from all others is you. You and you alone.

So the bottom line is this: do not allow the stage of disease to shut you down. Find support and take the steps to keep yourself healthy and strong whatever treatment options you face. Take it one step at a time.


American Cancer Society. "Colorectal Cancer Stages." Atlanta, Georgia; updated March 2, 2017.