Prostate Cancer Stages – Simplified

After getting a diagnosis of prostate cancer, you must undergo some extra tests to find out whether the tumor has spread or not. We express this as “stage 1”, “stage 2″… and so on. Let’s see what those stages mean.

Why are stages important?

In oncology, stages are a way to describe whether cancer has spread or is limited to the prostate gland. We use it for all tumors in the body, not only for prostate cancer.

The lower the stage, the more localized it is. For example, stage 1 cancer means the tumor hasn’t grown outside the prostate.

The higher the stage, the more the tumor has spread. Stage 4 cancer means there are distant metastases: the tumor has traveled to other organs such as the liver or bone.

Stages are important because they allow us to know the prognosis (can we cure the patient? and if not, what is the expected survival time?). Thus, knowing the prognosis we can choose the right treatment for each patient. For example, we will remove the tumor for a stage 1 cancer through surgery and we’ll give chemotherapy for a stage 4. It wouldn’t make sense to remove the tumor in a stage 4 cancer because the tumor has spread into distant organs.

Depending on how reliable the staging is, we have clinical staging (before surgery) and pathological staging (after surgery).

Clinical staging

We can consider it the “preliminary staging”. We can detect prostate in several ways:

• • Your doctor may touch it through a digital rectal exam, DRE.
  • It can also be found through an MRI.
  • Or through a needle biopsy of the prostate.

In any of these cases we can estimate the prostate cancer stages, but not with 100% certainty.

For example, the doctor can touch a small nodule limited to the prostate through DRE. But he can’t be sure that there are no lymph nodes in the pelvis.

If you get imaging tests like a full body C.T. or a pelvic MRI, your staging will be more accurate. These tests are good at finding local lymph nodes and distant metastases.

Let’s see the different stages:

• • T1. We cannot detect the tumor through digital exam or MRI. Instead, it is found accidentally through a biopsy or a transurethral resection (TUR).
  • T2. In this case, we can detect the tumor through digital exam or MRI and it’s limited inside the prostate capsule. That means, it doesn’t invade the surrounding organs.
  • T3. The tumor extends outside the prostate capsule. It can even invade the seminal glands (that would be a T3b).
  • T4. The tumor extends outside the prostate capsule affecting some pelvic organs other than the seminal glands.

Apart from this, the doctor will also determine your PSA through a blood test. PSA is the prostate-specific-antigen and its levels rise with prostate cancer (but it also rises with non-cancer conditions such as prostatitis and BPH).

Pathological staging

Once you undergo surgery we can get a more accurate staging.

The pathologist will study the prostate once we remove it and find out if the tumor is inside the prostate, invading the capsule, etc.

Also, the surgeon will check if there are affected lymph nodes during the surgery. By this time our staging is much more accurate and we call it pathological staging.

At this point, the prostate cancer stages depend on 5 factors:

• • The tumor (T)
    • how large is the tumor?
    • does it spread outside the prostate?
  • Lymph nodes affected (N)
    • are there pelvic lymph nodes affected?
    • abdominal lymph nodes?
  • Has cancer spread to other organs (M)?: 
    • hepatic metastases?
    • lung metastases?
    • bone metastases?
  • PSA levels at the time of diagnosis
  • Gleason score: it’s a number from 2 to 10, determined by the pathologist. It shows how undifferentiated the cells are. The higher the Gleason the more aggressive it is.
    • Gleason 2: very well differentiated. Probably slow growth, not so aggressive.
    • Gleason 10: undifferentiated. Probably fast growth and highly aggressive.

With all this information, there are again 4 stages:

• • Stage 1. The tumor is small and limited to the prostate gland. PSA is low. Gleason is low.
  • Stage 2. It includes 2A, 2B, and 2C. The tumor is limited to the prostate but there is an increased risk for spreading. Either the PSA is medium or the Gleason is higher than in stage 1 (the cells are less differentiated).
  • Stage 3. There is regional invasion: the tumor has grown outside of the prostate. It can invade the seminal glands, rectum, bladder… Or it hasn’t invaded them yet but it is undifferentiated (high Gleason) so chances are it will invade them. The PSA is usually high.
  • Stage 4. Cancer has spread either to pelvic lymph nodes, or distant lymph nodes or distant organs. It includes metastasis to the bone, liver, and other organs.

Each stage conveys a different prognosis and requires a different treatment. The higher the stage the more aggressive we have to be when treating it.

Check this other post about prostate cancer signs or this one about prostate cancer (in-depth post).