An Introduction To Prostate Cancer

Key Facts:

In New Zealand prostate cancer is the most common cancer diagnosed in men. About 1 in 4 cancers diagnosed in men are prostate cancer. It is however only the third most  common cancer cause of death (13% of cancer deaths), with lung cancer still the most common cause of cancer deaths in men. Roughly this means that about 3000 men are  diagnosed and 600 men die of prostate cancer each year in NZ.  

It is important however to remember that this means most men with prostate cancer do not die of the disease but live with the consequences of treatment, whether that treatment is curative, observation or drugs. The average age at diagnosis is 66. It is very rare before age 40. For more information on the statistics of prostate cancer see

http://seer.cancer.gov/statfacts/html/prost.html

What is the prostate?

The prostate is a small organ or structure found at the base of the bladder. It surrounds the tube (urethra) that urine passes through and gets bigger as men age. It is made of both muscle fibres and glands. The main function of the glands and therefore the prostate is to produce fluids that are mixed with sperm. One of these fluids is PSA.  Behind the prostate are the seminal vesicles. These also make a lot of fluid, together the fluid from the seminal vesicle, prostate and the sperm make up the seminal fluid or ejaculate or male cum. These fluids keep the sperm alive as it tries to get to the ovary or egg.


What is prostate cancer?

A cancer is an uncontrolled growth of cells. Sometimes these cells grow quickly but more often they are slow growing. Cancers can occur anywhere in the body. For a more in-depth discussion of cancer please see www.patient.co.uk/health/cancer-staging-and-grading-cancer.htm.

Prostate cancer is almost always an abnormal growth of the glands within the prostate . The prostate itself is composed of or made up of glands, muscle fibres and supporting cells. The cells of the gland secrete fluids which make up the ejaculate and part of this is  PSA. A cancer which begins in the cells of any gland in the body is called an adenocarcinoma. When we talk about "prostate cancer" we are really mean adenocarcinoma of the prostate as all other forms are so rare.

Prostate cancer usually begins in the outer portion of the prostate gland in an area called the peripheral zone. This means that when the tumour gets large enough it can be felt by a rectal examination.


Prostate cancers differ in their aggressiveness and size. We grade prostate cancers 1-5 and also stage prostate cancers. This is discussed in more detail below.


A small tumour in the peripheral zone of the prostate, this should be able to be felt on a rectal exam.


Why does prostate cancer develop?

This is not yet known. It appears to be as a result of inflammation or irritation in the gland over many years. More frequent ejaculation for example does appear to reduce the risk. Diet seems to play a role in developing clinically important prostate cancer and there is some evidence of a genetic or inherited risk as well.

As previously mentioned many men will develop small low-grade cancers as they age and the rate of these undetected small cancers is much the same in all societies.

The risk of detectable cancers differs between societies. The best example of this is the increase in the risk of prostate cancer in Japanese men as they migrate to the USA. The risk of clinically important prostate cancer increases as a Japanese male moves from Japan to Haiwai and then to mainland USA. The children of Japanese immigrants in the USA have the same risk as white Americains, indicating that diet seems to be important in taking small cancers and allowing them to grow or change.

Men who have first-degree relatives with prostate cancer or first degree females with breast cancer are at increased risk of developing prostate cancer. The BRACA 1 and 2 genes increase the risk of more aggressive prostate cancer. The importance of other genes has yet to be fully understood.

Do I need a prostate?

No. If the prostate is removed you will however be infertile. The problem in treating the prostate is that these treatments often affect the structures which surround the prostate. These are the nerves which control erections, the muscle which stops urine leaking and the rectum.

How is prostate cancer diagnosed?

Prostate cancer is usually diagnosed by a biopsy, see prostate biopsy. Before a biopsy the doctor will look at your PSA test, and do a rectal examination of the prostate. An x-ray called an MRI may also be done prior to the biopsy. At the biopsy small amounts of tissue are taken from the prostate and sent to a doctor called a pathologist to look at.

Are all prostate cancers the same?

No, different prostate cancers can behave very differently. The most important things are the grade and stage of the cancer. Low-grade early stage cancers will take many years to become dangerous and may never do so. High-grade cancers will take very little time to spread. The treatment options are therefore very different for different grade and stages of prostate at cancer.

What does grade of cancer mean?

Grade is a crude measure of how aggressive a cancer is. After a biopsy the pathologist looks down a microscope at the samples taken and tries to work out whether the prostate glands look normal or not.

If the glands are abnormal, and a  cancer is seen then the pathologist uses a grading system to try and rank the aggressiveness of the cancer cells seen. In general low-grade cancers look more like  normal  glands with well-formed glands present. As the cancer becomes more aggressive the structure of these glands break up, the cells look more bizarre and eventually the glands disappear altogether.

The standard system for grading prostate cancer is called the Gleason grade, named after an Americain pathologist. Although originally described on a scale of  1 to 5, grades 1 and 2 probably do not exist and now we only talk about grades 3, 4 and 5. ( One day we might see this changed so the scale starts at 1 but for now remember that grade 3 is the lowest grade of cancer seen).

Grade 3 is therefore the lowest grade you can be diagnosed with.  Prostate cancer is a bit odd in that it is often mixed up with different areas having different grades, rather than it being all the same. Because of this the pathologist gives grades for both the commonest and the next most common pattern seen. These two grades are then added together to make a Gleason score. So Gleason score is the sum of the two most common grades present and therefore ranges from 6 (3 + 3) to 10 (5+ 5). Gleason score 6 cancer is low grade and Gleason score 10 is very high grade.


As the glands become more abnormal the grade increases


This picture shows almost normal glands on the right (Gleason grade 3) and much more abnormal cells and glands on the left (Gleason grade 4). It would therefore be  given a Gleason score 7(3+4, or 4+3).

What does T stage mean?

The T stage of a cancer means how far has the cancer spread. In prostate cancer we talk about stage T1,2,3 and 4. T1 cancer is cancer that cannot be felt. This can be because the cancer is small or at the front of the prostate (anterior).  T2 is a cancer that can be felt on rectal examination but is thought to be still within the prostate, T3 is a cancer which appears to be outside the prostate and T4 is a cancer that has spread to adjacent or nearby tissues or structures. T1, 2 prostate cancers should be able to be cured. T3 can sometimes be cured and T4 can be controlled but not cured.

The different T stages of prostate cancer are illustrated below.


Stage usually refers to how far has the cancer spread locally and at distant places. So stage is a combination of local and distant spread.

Early prostate cancer (stage 1) is cancer confined to the prostate. Stage 2 is cancer that is in or close to the prostate but has not spread to other sites. Stage 3 is cancer that has spread to local sites and stage 4 is a prostate cancer that has spread to other parts of the body.

We can think of prostate cancer therefore as being locally confined (that is still in the prostate), just outside the prostate but without spread (locally advanced) or with spread to the lymph nodes of the pelvis or spread to distant places such as the bones.

How is prostate cancer treated?

The treatment of prostate cancer depends on four factors. These are the age of the person affected, the various illnesses the person has, the grade of the cancer and the stage of the cancer. The question really is how long are we likely to live and how bad is the cancer?

Broadly speaking for early to intermediate prostate cancer we can treat prostate cancer by observing the prostate cancer (watchful waiting), watching the cancer but planning to treat the cancer if it seems to be growing (active surveillance), removing the prostate with surgery (radical prostatectomy) or treating the cancer with radiotherapy.

For more advanced cancer surgery is not suitable but radiotherapy may still be effective. For cancer that has spread the treatment options are between medicine (androgen deprivation therapy) and radiotherapy or both together.

The question is always

  • Do I need to treat the cancer now or can it safely wait?
  • If I do treat the cancer how should it be treated?

The treatment options are discussed in more detail in the treatment sections. Further information is available through the following websites.

Web Resources:

There are an enormous number of websites on the net. Here is a selection of some sites that may be of help.

NZ sites:

Prostate cancer foundation of NZ.

Cancer society of nz.

http://www.getthetools.org.nz/uploaded/Prostate%20Information%20Sheet%202013.pdf

Department of Health.

UK Information site (very good)

http://prostatecanceruk.org

http://prostatecanceruk.org/media/41578/2407-newly-diagnosed-booklet-ifm.pdf

USA information.

http://www.cancer.gov/cancertopics/pdq/treatment/prostate/

http://www.cancer.gov/cancertopics/pdq/treatment/prostate/Patient

http://www.cancer.org/cancer/prostatecancer/detailedguide/

European Guidelines (maybe too much information).

http://www.uroweb.org/gls/pdf/08%20Prostate%20Cancer_LR%20March%2013th%202012.pdf

Australian site

http://www.yananow.net

Drug company based information.

http://www.prostate.com/patient/

For wives/partners.

http://www.phoenix5.org

http://www.hisprostatecancer.com

Treatment options

http://www.ccjm.org/content/78/5/321.full.pdf