Prostate -

Adenocarcinoma

This article was last reviewed and updated on August 12, 2019

by Trevor A. Flood, MD FRCPC

Quick facts:

  • Adenocarcinoma is the most common type of prostate cancer.

  • Most men who develop adenocarcinoma are 50 years old or older.

  • Your pathology report for adenocarcinoma will include important information about the tumour such as the histologic type, the Gleason grade, and the Gleason score.

The normal prostate

The prostate is a small organ that is found only in men.  The prostate is normally the size and shape of a walnut.  It is located at the bottom of the bladder and sits between the pubic bone (i.e the front part of the hip) and the rectum.  The prostate also wraps around the urethra. The urethra is the tube that conducts urine from the bladder and semen from the ejaculatory ducts to the exterior of the body.  The prostate releases a fluid that helps feed and move sperm that come from the testicles.  This fluid is made in by a complex network of small structures called glands and is then transported out of the prostate through channels called ducts.  

What is adenocarcinoma?

Adenocarcinoma is a type of prostate cancer that develops from the glands normally found in the prostate. 

 

Adenocarcinoma of the prostate is a relatively common cancer among older men.  The risk of getting prostate cancer increases after a man turns 50 years old. Other risk factors include:

 

  • A family history of prostate cancer.

  • Coming from African or Caribbean ethnicity

  • Obesity.  

 
Prostatic adenocarcinoma can appear and progress very differently in each person. Many tumours grow slowly. Some men can live many years before the cancer is detected. Some tumours are aggressive. Aggressive cancer should be treated right away.

 

Most tumours in the prostate are found after a doctor examines manually examines your prostate. This procedure is called a digital rectal examination. If an unusual lump is found, the next step is a core needle biopsy. A biopsy can also be done after a blood test shows high levels of the prostate-specific antigen (PSA). Most biopsies usually involve 10 to 15 samples of tissue taken from different parts of the prostate.   

Your pathologist  will examine the tumour  under a microscope.  What they see (microscopic features) will help them predict how the disease will behave. These same features will help you and your doctors decide which treatment options are best for you.   If the biopsy confirms prostatic adenocarcinoma, your doctor will talk to you about treatment, which may include active surveillance (see below), radiation, or surgery to remove the tumour.

Histologic type

There are different histologic types of adenocarcinoma of the prostate based on the shape and size of the tumour cells and the way that they grow. Your pathologist can only decide the histologic type of adenocarcinoma after examining a sample of your tumour under the microscope.  

 

Most prostate adenocarcinomas are called acinar, not otherwise specified, which means they are growing as groups of cells that resemble small glands. This type is by far the most common histologic type of prostate cancer.

Other histologic types are rare but include:

  • Intraductal carcinoma of the prostate (IDC-P)

  • Ductal prostatic carcinoma

  • Adenosquamous carcinoma

  • Small cell neuroendocrine carcinoma.

Why is this important? The type of cancer is important because each type will behave differently and some are associated with worse prognosis. 

Gleason grade

Your pathology report for prostatic adenocarcinoma will likely contain a lot of information about the Gleason grade and the Gleason score (see Gleason score below).  Both are made up of numeric scales. The Gleason grade ranges from 1-5 and the Gleason score ranges from 2 and 10.

  

Your pathologist will decide the Gleason grade after examining the tissue under the microscope. The grade is based on how different the tumour cells they look compared to normal glands in the prostate.  

 

Your pathologist will then give the tumour a number between 1 and 5. Tumours that look similar to normal glands are given a lower number.  These tumours tend to be slow growing and less aggressive.  Tumours that do not look like normal glands are given a higher number and tend to be more aggressive.  These tumours can grow quickly and spread. 

Important note: Gleason grade 1 and 2 tumours are not typically diagnosed. These grades are noted as part of your health history only. As a result, Gleason grades actually range from 3-5 (instead of 1-5) and Gleason scores range from 6-10 (instead of 2-10).

 

Gleason score

The Gleason score is calculated by adding up the two most common Gleason grade numbers in your tumour. For example, if your tumour is made up of 70% Gleason grade 3 and 30% Gleason grade 4, then your Gleason score would be 3+4=7.  If only one Gleason grade is seen then the primary and secondary patterns are given the same grade.  For example, if your tumour is made up 100% of Gleason grade 3, then your Gleason score is 3+3=6.

Why is this important? The Gleason score is important because it can be used to predict the behavior of the tumour.

Gleason group

The prostate cancer Gleason Grade group is a new grading system that is based on information from the Gleason score. The Grade groups range from 1-5. See table below for more information.

 

Why is this important? All tumours within a Gleason Grade group are likely to behave in a similar manner and patients within the same group have similar prognosis.  

Active surveillance

Active surveillance is a treatment option for men who have low grade (Gleason score 3+3=6 or Grade group 1) prostate cancer detected by a biopsy. Since the cancer is growing slowly, there is no need to remove it right away because it likely poses no risk to the patient.

Active surveillance involves monitoring the patient with:

  • Regular prostate specific antigen (PSA) blood tests.

  • Regular manual examinations of the prostate (digital rectal examination).

  • Occasional core needle biopsies.

Patients will be offered treatment (surgery or radiation) at the first sign that the prostate cancer has progressed or if it has changed into a more aggressive type of tumour (pathologists call this ‘transformation’).

Why is this important? Active surveillance avoids invasive treatments for low-risk cancer that is growing slowly. 

Tumour quantification

The tumour quantification is the percentage of the prostate replaced by cancer cells. This gives an estimate of how big the tumour is. Your pathology report will describe how many tissue samples show cancer cells. Your report will also describe what percentage of each sample was replaced by cancer cells.

 

Why is this important? This information will help your doctor and you decide which treatment options are best for you.

Extraprostatic extension​

Extraprostatic extension describes cancer cells that have moved outside of the prostate and into the tissue surrounding the prostate. If cancer cells are seen in the tissue outside of the prostate, it will be described in your report. ​

 

Why is this important? Extraprostatic extension is associated with worse prognosis and is used to determine the tumour stage (see Pathologic stage below).

Seminal vesicle invasion

The seminal vesicles are organs that are located behind the bladder and above the prostate. Each person has two seminal vesicles and one is located on each side of the prostate. These organs produce and store the fluid that is sent to the prostate to feed and move sperm.  

 

The movement of cancer cells into the seminal vesicles is called invasion.

 

Why is this important? Seminal vesicle invasion is associated with worse prognosis and is used to determine the tumour stage (see Pathologic stage below).

Urinary bladder neck invasion
​The bladder rests above the prostate gland. Invasion means that cancer cells have traveled directly from the prostate into the lower part of the bladder known as the bladder neck.

Your pathologist will look for cancer cells in the bladder neck.   

 

Why is this important? Cancer cells in the bladder neck is associated with worse prognosis and is used to determine the tumour stage (see Pathologic stage below).

Perineural invasion

Nerves are composed of bundles of neurons, which are individual cells that transmit information between your brain and your body.  The presence of cancer cells wrapping around a nerve is called perineural invasion.  

 

Why is this important? Perineural invasion that is found in a prostate biopsy may be associated with worse prognosis. That is because perineural invasion found in a biopsy has been shown to be associated with extraprostatic extension (see Extraprostatic extension above).  In contrast, finding perineural invasion after the entire prostate has already been removed (a resection) has been shown to be of no importance.  

Lymphovascular invasion

Blood moves around the body through long thin tubes called blood vessels. Another type of fluid called lymph which contains waste and immune cells moves around the body through lymphatic channels.


Cancer cells can use blood vessels and lymphatics to travel away from the tumour to other parts of the body. The movement of cancer cells from the tumour to another part of the body is called metastasis.


Before cancer cells can metastasize, they need to enter a blood vessel or lymphatic. This is called lymphovascular invasion.


Why is this important? Lymphovascular invasion increases the risk that cancer cells will be found in a lymph node or a distant part of the body such as the lungs.

Margins

A margin is the rim of tissue that surrounds the surgical specimen that was cut by the surgeon in order to remove the tumour from your body. The margins will only be described in your report after the entire tumour has been removed.
 
In the case of prostatic adenocarcinoma, a margin is considered positive when there are cancer cells seen at the very edge of the cut tissue. This means that the surgery may not have removed all of the cancer cells from your body.   

 

A negative margin means that there are no cancer cells seen at the edge of the cut tissue. This means that it was more likely that all of the cancer cells were removed during the surgery.

Why is this important? A positive margin  may be associated with a higher risk that the tumour will come back (recur) in the same site after treatment.

Treatment effect
​If you received treatment (either androgen deprivation therapy or radiation therapy) for your cancer prior to the tumour being removed, your pathologist will examine all of the tissue submitted to see how much of the tumour is still alive (residual tumour).

Lymph nodes

Lymph nodes are small immune organs located throughout the body. Cancer cells can travel from the tumour to a lymph node through lymphatic channels located in and around the tumour (see Lymphovascular invasion above). The movement of cancer cells from the tumour to a lymph node is called a metastasis

Your pathologist will carefully examine all lymph nodes for cancer cells. Lymph nodes that contain cancer cells are often called positive while those that do not contain any cancer cells are called negative. Most reports include the total number of lymph nodes examined and the number, if any, that contain cancer cells.

Lymph nodes on the same side as the tumour are called ipsilateral while those on the opposite side of the tumour are called contralateral.

Why is this important? The number of lymph nodes found to contain cancer cells is used to determine the nodal stage (see Pathologic stage below). Finding cancer cells in a lymph node is associated with worse prognosis and may require additional treatment.

Pathologic stage
​​The pathologic stage for prostatic adenocarcinoma is based on the TNM staging system, an internationally recognized system originally created by the American Joint Committee on Cancer.

 

This system uses information about the primary tumour (T), lymph nodes (N), and distant metastatic disease (M)  to determine the complete pathologic stage (pTNM). Your pathologist will examine the tissue submitted and give each part a number. In general, a higher number means more advanced disease and worse prognosis.

 

The pathologic stage will only be described in your report after the entire tumour has been removed in a resection (radical prostatectomy) specimen.


Tumour stage (pT) for adenocarcinoma of the prostate

Your pathologist will give your tumour a tumour stage between 2 and 4 based on what they have observed after examining your prostate specimen under the microscope.  The tumour stage is based on how far the cancer cells have traveled outside of the prostate (invasion).

  • T2: The tumour is found inside the prostate only.

  • T3: The cancer cells have traveled outside of the prostate and into the fat, seminal vesicles, and/or into the bladder neck.

  • T4: The cancer cells have traveled into other nearby organs or tissues such as the rectum or pelvic wall.


Nodal stage (pN) for adenocarcinoma of the prostate

Prostatic adenocarcinoma is given a nodal stage of 0 or 1 based on the presence of cancer cells in a lymph node. If no lymph nodes contain cancer cells, the nodal stage is N0. If no lymph nodes are sent for pathological examination, the nodal stage cannot be determined and the nodal stage is listed as NX.

Metastatic stage (pM) for adenocarcinoma of the prostate 

Prostatic adenocarcinoma is given a metastatic stage (pM) of 0 or 1 based on the presence of cancer cells at other locations in the body (for example a bone). The metastatic stage (pM) can only be determined if a pathologist examines the tissue from another site of the body. Because this tissue is not typically sent to the lab, the metastatic stage (pM) can not be determined and is listed as pMX.

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