by Trevor A. Flood, MD FRCPC
September 30, 2022
Adenocarcinoma is a type of prostate cancer. It develops from the glands normally found in an organ called the prostate gland. 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. 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 manually examines your prostate gland. This procedure is called a digital rectal examination. If an unusual lump is found, the next step is to take several small tissue samples from the prostate in a procedure called a core needle biopsy. Most biopsies usually involve 10 to 15 samples of tissue taken from different parts of the prostate. A biopsy can also be done after a blood test shows high levels of the prostate-specific antigen (PSA).
Your pathologist will then examine the tissue samples under a microscope. What they see (the 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. These options may include active surveillance (see below), radiation, or surgery to remove the tumour.
There are different 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 type of adenocarcinoma after examining a sample of your tumour under the microscope. The type of adenocarcinoma is important because each type will behave differently and some are associated with a worse prognosis.
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:
Your pathology report for prostatic adenocarcinoma will likely contain a lot of information about the Gleason grade and the Gleason score. Both are made up of numeric scales. The Gleason grade ranges from 1-5 and the Gleason score ranges from 2 and 10. Both the Gleason grade and Gleason score are important because they help predict how the tumour will behave over time.
Your pathologist will decide the Gleason grade after examining the tissue under the microscope. The grade is based on how different the tumour cells 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).
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. The Gleason score is important because it can be used to predict the behaviour of the tumour.
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 the table below for more information. All tumours within a Gleason Grade group are likely to behave in a similar manner and patients within the same group have a similar prognosis.
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 avoids invasive treatments for low-risk cancer that is growing slowly.
Active surveillance involves monitoring the patient with:
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’).
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. This information will help your doctor and you decide which treatment options are best for you.
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. Extraprostatic extension is associated with a worse prognosis and is used to determine the tumour stage (see Pathologic stage below).
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. Seminal vesicle invasion is associated with a worse prognosis and is used to determine the tumour stage (see Pathologic stage below).
The bladder rests above the prostate gland. Invasion means that cancer cells have spread 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. Cancer cells in the bladder neck are associated with a worse prognosis and are used to determine the tumour stage (see Pathologic stage below).
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.
Perineural invasion that is found in a prostate biopsy may be associated with a 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 has been shown to be of no importance.
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. Lymphovascular invasion is important because it increases the risk that cancer cells will be found in a lymph node or a distant part of the body such as the lungs.
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 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. 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 positive margin may be associated with a higher risk that the tumour will come back (recur) in the same site after treatment.
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 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 lymph node 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. 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 a worse prognosis and may require additional treatment.
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 a worse prognosis.
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 spread outside 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.
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.