Prostate Cancer

Prostate Cancer Stages Explained

Prostate cancer begins in the male prostate gland located in the lower abdomen.

The prostate is active during male ejaculation and orgasm and produces the fluid that lubricates and nourishes the ejaculated sperm.

Other than skin cancer, it is the most common cancer found in men and men can often live for years without ever knowing they have it.

Studies have shown that many men die of other causes and are found to have prostate cancer during an autopsy.

Such indolent prostate cancer was likely present for many years and caused little to no symptoms. 1

Prostate cancer is very treatable, especially for those whose cancer has not spread beyond the prostate.

Being Diagnosed with Prostate Cancer

According to the American Cancer Society, the 5-year survival rate for prostate cancer is close to 100 percent. Ten and fifteen years, survival rates are also well over 90 percent.

In many cases, prostate cancer is discovered via a suspicious finding during prostate cancer screening, such as a digital rectum examination (DRE), MRI (Magnetic Resonance Imaging) or a PSA blood test during a routine annual physical.

Most men, on being diagnosed with prostate cancer, enter into an involuntary shock mode. Both the man and his partner may be psychologically looking for someone to tell them what to do or make decisions for them.

This roller-coaster of additional tests, decisions, and emotions often results in patients being scared into treatment just to feel as if they are doing something.

This can result in over-treatment. Bearing in mind that all treatment for prostate cancer carries serious side effects, a newly diagnosed man and his partner would be well-advised to seek out all information they can find and make their own decisions rather than leaving them in the hands of their time-constrained doctor.

Like many other cancers, prostate cancer is medically described by stages that define how and where the cancer is located as well as it’s level of aggressiveness.

Knowing the stage can help define the approach to treatment as well as whether or not aggressive treatment is needed. Staging is important to help medical practitioners recommend the best method of treatment.

It is particularly important for higher stages of the disease where a treatment option like surgery may be ruled out.

Surgery is unlikely to affect a cure when cancer has already spread beyond the prostate. Knowing the stage is also useful, helping to select the most minimally invasive treatment consistent with the most tolerable side effects.

Prostate Cancer Screening

Initial staging of prostate cancer generally uses three measurable result parameters: A digital rectal examination (DRE); a prostate-specific antigen (PSE) blood test; and a Gleason score from the pathology report on a biopsy.

From this initial data, other tests such as; x-rays, bone scans, CT or MRI scans, may be justified depending on the extent of the disease.

If a biopsy or radical prostatectomy has been performed, pathological data of tissue from biopsy cores or the surgically excised gland can be used to refine the staging of the disease further.

From this combined data, an overall stage, typically numbered from one to four using roman notations (I – IV), is assigned and used by medical personnel during treatment and evaluation.

This overall disease stage is determined by combining several other measured or computed components. A measurement system called TNM defines one component.

This system defines the tumor size and location (T), lymph node involvement (N), and metastasis beyond the prostate gland (M).

Doctors sometimes use a grade of zero for any of the parameters to indicate negative findings. An “X” after any of the letters indicates that the parameter could not be evaluated. These determinations are typically assigned using the TNM system on tissue removed during surgery or a biopsy.


For more information on prostate cancer screening click here.


Tumor stages

The “T” part of the TNM system defines the tumor and is split into four sub-parts, T1, T2, T3, and T4. These subparts are divided further, as shown below:

T1: The tumor was found due to ancillary surgery, but not felt during a DRE or seen during imaging. This is subdivided into categories of a, b, and c, depending on the size of the tumor.


T2: A tumor is large enough to be felt during a DRE. This is further divided into categories of a, b, and c, depending on the size of the tumor and its location in the prostate.

T3: The cancer has grown through the capsule surrounding the prostate. Subcategories of a and b are used to define the amount of extension into nearby structures such as the seminal vesicles.

T4: The tumor has spread outside the prostate into other nearby structures.

cancer tumor

Lymph node stages

The “N” part of the TNM system indicates whether or not the cancer is found in surrounding lymph nodes.

This section has two sub-parts, N0 or N1, indicative of whether or not cancer has spread to the nearby lymph nodes.

 lymph node
 Lymph node stages.

Metastasis Stages

The “M” part of the TNM system indicates whether or not cancer has spread (metastasized) to other areas of the body.

It is further divided into categories of a, b, and c, depending on where cancer has been discovered outside of the prostate.

M1a indicates cancer has spread to distant lymph nodes.

M1b indicates metastasis to the bones.

M1c indicates it has spread to other distant areas.

metastasis stages
Metastasis Stages.

What is the Gleason Score?

The Gleason score is a pathological cell analysis obtained after either a biopsy of the prostate or its surgical removal.

The excised tissue is analyzed by the examining pathologist who looks specifically at the shape of the removed prostate cells. It is named for a pathologist, Donald Gleason who categorized prostate cells for cancer in the 1960s.

Dr. Gleason noted five distinct patterns of prostate cells as they morphed from normal into tumor cells and assigned a grade from 1 to 5 to each of these distinct shapes.

Normal prostate cells are round and clearly defined (well-differentiated) and are not assigned any grade or assigned a grade of zero. Cancerous cells typically have ragged edges and are not well-differentiated.

Cancer cells that most resemble normal prostate tissue are given grade 1, Cells that are most ragged and have mutated way beyond the shape of normal cells are given a grade of 5.

Thus, the Gleason score represents the actual cells of the tumor, numerically rated by how much they differ from normal.

A tissue sample scored as 1 or 2 is considered low-risk, and a score of 5 is a high-grade, potentially aggressive cancer. In practice, scores of 1 to 2 are rarely used by pathologists.

The lowest practical grade is usually 3 for any sample. The overall Gleason score results from adding the numeric score of the two tissue samples containing the most poorly differentiated cells.


For more information on the Gleason Score click here.


Significance of the Gleason Score

The two numeric scores assigned to the tissue samples represent the first and second most predominant cell patterns.

They are then added together to form the final score which is given as a total followed by two numbers in parenthesis.

For example, a Gleason score of 7 (3+4), means the first and second predominant tissue patterns were 3 and 4. Thus, a score of 7, formed by a most predominant sample of 3 added to a second-most predominant sample of 4 is slightly less aggressive than if a score of 7 is formed by adding 4 +3.

While the final Gleason score can theoretically range from 2 to 10, where 2 would represent two tissue samples graded at 1, pathologists rarely assign scores below 3 to any sample. Thus, in practice, the minimum Gleason score is 6, representing two samples of 3.

This appears to be due to multiple factors, including pathologists’ reluctance to use lower scores fearing they will miss significant cancer. The reality today is that men with a Gleason score of 6 have low-risk disease, but are often treated with a one-size-fits-all approach.

This leads to over-treatment when diagnosed with prostate cancer, and its accompanying side effects to be rendered when not really necessary.

Patients and some doctors often tend to view a definition of prostate cancer of any grade or Gleason score as a potentially lethal diagnosis to be treated in all cases. However, the evidence is conclusive that this results in significant over-treatment. 2

There has been much speculation about whether Gleason scores tend to increase with time, but the many variables involved in periodic testing make an accurate determination impossible.

The latest consensus is that it is substantially constant giving men that choose to use active surveillance a little positive reinforcement. 3

Final Stage Assignment

In addition to the grade determined by the TNM system, prostate cancer is also grouped into four final stages that combine all assessment findings.

This includes pre-biopsy or surgery screening data as well as any PSA blood tests and digital rectal examinations performed.

Thus, the final stage of the cancer is determined by multiple factors brought together by the attending doctor as well as the opinions of other participating doctors.

Below is a brief synopsis of the four prostate cancer stages.

  • Stage I: This early-stage cancer is typically localized and slow-growing (low-grade cancer), and for older men, maybe the kind of cancer that a man dies with, rather than from.

    While it is cancer, it causes few problems and symptoms. Apart from the diagnosis by incidental testing, a man may never know he has it.

    PSA levels are generally low, and the Gleason score is most commonly 6. This type of cancer is most amenable to a watchful waiting/active surveillance approach.

  • Stage II: These tumors are also localized in the prostate. The cancer cells are moderate to well differentiate on laboratory examination, and PSA levels are typically less than 20.

    Gleason score is typically 6 or 7. This stage is often divided into three sub-stages defined as IIa, IIb, and IIc, depending on the size and location of the tumor.

  • Stage III: The tumor has spread beyond the outer layer of the prostate into nearby tissues or the seminal vesicles.

    PSA level is 20 or greater. While the tumor is still confined to the pelvic area, this stage is indicative of cancer that is likely to exhibit growth.

    Gleason score is typically greater than 7. The cancer cells across the tumor are moderate to poorly differentiated, indicating cancer may eventually metastasize.

  • Stage IV: This stage indicates that the tumor has metastasized or spread beyond the prostate. This is known as metastatic prostate cancer.

    PSA level is usually greater than 20, and Gleason scores are correspondingly high and may go all the way to 10.

    This stage is usually divided in half to IVa and IVb. The first indicates cancer has spread to lymph nodes in the general region, and the second indicates metastasis to distant lymph nodes or other parts of the body or bones.

    This is the most severe grade of prostate cancer and is generally treated by traditional cancer treatments such as chemotherapy or radiation.

    Since the tumor is no longer confined to the prostate, surgical removal of the prostate is usually not an option.

For more information on prostate cancer surgery click here.


Overall Risk Factors

The risk factor of prostate cancer is a variable that is usually defined in three categories: low, moderate, and high risk.

The risk determination is established based on results of the PSA test, digital rectal exam, scans (if any), and tissue analysis from a prostate needle biopsy or surgery.

The primary provider typically determines a risk assessment, but this determination often requires subjective, rather than quantitative evaluation. Knowing the risk factor is important when making a treatment choice.

  • Low risk – This is cancer that typically stages I or a small tumor that falls into the stage II category. In either case, the cancer is not likely to grow swiftly or cause symptoms.

    For older men, with a life expectancy of fewer than 10 years, the low-risk disease may never cause any symptoms. Men in this category typically do well using active surveillance.

  • Medium risk – Describes a cancer that is more likely to grow. It is typically a stage II cancer, and if it is in one of the higher subcategories of stage 2, most men might want to treat it with radiation or surgery.

    Older men with lower PSA readings, low Gleason scores, and relatively small tumors confined to the prostate gland may also opt for the active surveillance approach.

  • High risk – Usually describes cancers that fall into the stage III or stage IV category. This is advanced prostate cancer, which has a higher probability of progressing in size or spreading to other areas. Aggressive treatment is almost always recommended.

Discussion

There are many factors that go into determination of the final stage of prostate cancer. Unfortunately, the word “cancer” brings with it an inordinate fear of dying in the eyes of many patients.

The diagnosis alone raises significant fear regardless of the stage. Thus, many patients fall into a mental state where they believe that they must get the cancer out of their body or die.

In addition, some doctors take an approach whereby they believe that all cancer, no matter how minimal must be treated.

This inherent bias and fear often causes men to accept treatments due to overreaction rather than medical necessity.

Often, patients insist on being treated even if their doctor recommends a wait-and-see approach.

Many different types of doctors can be involved in cancer treatment. Most commonly, urologists are the first (and sometimes the only) practitioner that a patient sees, often the first time a PSA result is out of range.

What many patients do not know is that almost all urologists are surgeons; thus, their typical recommendation is surgery.

In some cases, especially stage IV, where the cancer has spread beyond the prostate, surgery may have little effect on the overall progression of the disease. In such cases, an oncologist that does not specialize in surgery should be selected.

Many medical professionals, including medical and radiation oncologists, can serve as the principle professional treating prostate cancer.

A urologist may be part of the team, but doctors of different disciplines often work together and combine different type of treatments.


For more information on active surveillance click here.


Some Considerations…

Local treatments for localized prostate cancer such as surgery and radiation therapy, are nearly 100 percent effective.

For men diagnosed with low-risk early-stage prostate cancer, such treatments may completely rid the body of cancer.

For higher risk disease, systemic treatments like chemotherapy or hormonal therapy may be in order.

Systemic treatment is typically used in an attempt to destroy prostate cancer cells located in other parts of the body.

All treatments for prostate cancer (with the exception of watchful waiting/active surveillance) have significant life-altering side effects.

Many prostate cancer patients leave all staging and treatment decisions to the principle doctor treating them. However, while the staging of the cancer is best left to the medical professional, treatment decisions should always be the primary concern of the patient.

For example, both radiation therapy and surgery are routinely used to treat prostate cancer. Both work well on localized disease, and the risk of the cancer spreading is low. However, both treatments can cause incontinence, erectile dysfunction, bowel or bladder problems, and other issues.

However, the likelihood of a particular side effect often varies with the treatment. Surgery is more likely to cause incontinence and erectile dysfunction, while radiation therapy is more likely to cause bowel issues.

Patient psychological issues may play significant decisions in selecting a treatment option.

For some men, the idea of living with cancer in their body is inconceivable. They would rather be sure the cancer is removed via a prostatectomy, even though that may suffer the side effects of the treatment for the rest of their lives.

For such men, surgery is typically the chosen option. Based on the latest studies, treatment of a low-risk disease may not prolong a man′s life, but will definitely subject him to serious side effects and a lower quality of life.

For some men, the thought of losing sexual function is more important than total removal of the cancer. In this case, radiation may be a more palatable option.

If a man can tolerate the thought of living with his cancer and has low-risk, localized disease, active surveillance might be the best choice.

A man with a higher-risk disease may also choose active surveillance if his sexual functioning is of paramount importance to him.

Conclusion

A treatment decision should take into account an evaluation of the patient′s tolerance of various side effects as well as the patient′s age and life expectancy.

An older man, with low-risk disease and a life expectancy of fewer than ten years, would be well-advised to choose active surveillance.

Finally, no matter which treatment is chosen, a wise man will place the choice in his own hands. He should also remember that, with any procedure, success is based on the skill of the performing doctor.

Choosing doctors that have extensive experience and success with any chosen procedure increases the chances of a successful outcome enormously.

Sources

  1. Jaquelyn L. Jahn, et al, The High Prevalence of Undiagnosed Prostate Cancer at Autopsy: Implications for Epidemiology and Treatment of Prostate Cancer in the Prostate-Specific Antigen-Era, Int J Cancer. 2015 Dec 15; 137(12): 2795–2802.
  2.  H. Ballentine Carter, et al, Gleason Score 6 Adenocarcinoma: Should It Be Labeled As Cancer?, J Clin Oncol. 2012 Dec 10; 30(35): 4294–4296.
  3. Kathryn L. Penney, et al, Gleason Grade Progression Is Uncommon, Cancer Res. 2013 Aug 15; 73(16)

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