Anatomy and Function of the prostate
Compiled July 2018
What is it?
The prostate is a small gland about the size and shape of a walnut. It is part of a man’s internal sex organs. All the sex organs play a role in reproduction. The prostate generally increases in size as men age.
Where is it?
It is situated under the bladder and surrounds the urethra which is the tube that transports urine from the bladder to the penis where the urine is released through the ureter. This why problems with the prostate often affect the ability to urinate, causing what doctors call (urinary symptoms). The rectum sits directly be
hind the prostate. This means that a part of the prostate can be felt if a finger is inserted up the rectum. (digital rectal examination) or the “finger” test. The tube that carries the semen from the testicles feeds into the ejaculatory ducts which then connect to the seminal vesicles which are just above the prostate. When prostate cancer spreads it often spreads first into these structures that surround the prostate. The prostate has gland tissue and smooth muscles fibres which help it to contract when a man ejaculates. The prostate is surrounded by a loose capsule which is connected to sheaths of pelvic muscles. Before 1981 surgeons were not aware of the nerve bundles towards the back and sides of the prostate that play an important role in erections. The identification of these nerves led to the first “nerve sparing” prostatectomy in 1982. Knowing where these nerves are situated has made a big difference to minimising erectile dysfunction in men who have had a prostatectomy.
Until a few years ago, doctors described the different parts or areas of the prostate as lobes (see illustration below). One method of staging prostate cancer was to determine which lobes had been affected by cancer cells.
A more up-to-date way of describing the different areas of the prostate is the Zonal System. (See illustration below). 80 to 85% of prostate cancers start in the peripheral zone.
What does it do?
The prostate gland produces prostatic fluid which makes up about 15 to 30% of the semen or ejaculate. The average amount of semen ejaculated is 3.4ml which is less than a teaspoon full. Sperm make-up only 1 to 5% of the total volume of the ejaculate. The secretions from the seminal vesicles make-up the majority of the ejaculate. The secretions from the various glands that help to produce semen all assist with nourishing and protecting the sperm so that they can survive and impregnate an egg in the process of reproduction.
(1) Nicholas J., Primer on Prostate Cancer-2014, Springer Healthcare 2014.
(2) William K, Hurwitz M, D’Amico AV, et al. Biology of Prostate Cancer. Holland-Frei Cancer Medicine. 6th edition. Hamilton (ON): BC Decker; 2003. Available from: https://www.ncbi.nlm.nih.gov/books/NBK13217/
(3) Owen DH., Katz DF. A Review of the Physical and Chemical Properties of Human Semen and the Formulation of a Semen Simulant. J Androl 2005;26:459–469.
How common is Prostate Cancer in South Africa?
According to Globcan, prostate cancer is the most frequently diagnosed cancer among men in over one‐half the countries of the world including the Americas, Northern and Western Europe, Australia/New Zealand, and much of Sub‐Saharan Africa. It is the leading cause of cancer death among men in 46 countries, particularly in Sub‐Saharan Africa and the Caribbean. (1a)
Although there are no reliable statistics on the incidence of prostate cancer amongst South African men, it is possible to get an idea of how common prostate cancer is in South African men by looking at the data from countries where men have reasonable access to screening for prostate cancer and where there is a significant population of black men with African ancestry. (Race is a proven risk factor for prostate cancer with black American and Jamaican men of African descent having the highest recorded rates of prostate cancer worldwide). (2a)
In the USA approximately 11.2 percent of all men will be diagnosed with prostate cancer at some point during their lifetime according to The SEER data from the National Cancer institute. (3) However if we compare the rates of prostate cancer in white vs black African American men there is a significant difference. It is estimated that 1 in 6 black African American men will be diagnosed with prostate cancer in their lifetime compared with 1 in 8 white American men. (2b) If we look at the data from 2008 to 2012 it showed that Black African American men had a 70% greater chance of being diagnosed with prostate cancer than white American men. (2c) They were also more than twice as likely to die from prostate cancer as their white counterparts, although this has improved in recent years.(2d)
One major advantage that black American men have over black South African men is that they are more likely to be diagnosed when the cancer is at a local or regional stage.(2e) (In other words, before it has spread to other parts of the body). This means that after 5 years most of these men will still be alive. In South Africa, the majority of black men will only be diagnosed when the cancer has spread, this is called metastatic prostate cancer and it is incurable.4 This means that after 5 years only about 30% of these men will still be alive. (5) Black African men from Southern Africa appear to have an additional disadvantage in that they present with significantly more aggressive prostate cancer than African Americans. (1b)
According to Prostate Cancer UK, 1 in 8 men will be diagnosed with prostate cancer at some point in their lives(6a) and for black British men of African descent 1 in 4 men can expect to be affected. (6b)
We recommend that black South African men consider screening from the age of 40 and that other ethnic groups start screening from 45.
Prostate cancer is more common in men with a family history of prostate cancer. If you have a family history of prostate cancer you are twice more likely to get prostate cancer. Having a brother with prostate cancer appears to put you at a higher risk than if you have a father with prostate cancer. The more family members affected by prostate cancer the more likely you are to get it. (7)
There is some evidence showing that prostate cancer is also more common in men who have a first degree relative who has been diagnosed with breast cancer, particularly when the breast cancer was diagnosed before the age of 50. (8) Men who have a daughter who has been diagnosed with breast cancer have a higher risk for aggressive prostate cancer.
We recommend that men with a family history of prostate or breast cancer in a first degree relative consider screening from the age of 40.
- Based on current USA and UK data and various clinical studies:
- About 1 in 8 to 1 in 9 white South African men are likely to be affected by prostate cancer.
- As life expectancy amongst black South African men increases, between 1 in 4 and 1 in 6 men are likely to be affected by prostate cancer. Black men are more likely to get prostate cancer at a younger age and a more aggressive type of prostate cancer.
- Prostate cancer is more common in men with a family history of breast and prostate cancer.
- Men who are at increased risk for prostate cancer because of their race or family history should consider screening for prostate cancer from the age of 40
- All other men should consider screening from the age of 45
Ref 1 Bray F et al. Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. Ca: A journal for Clinicians. Vol 68 no. 10 Nov/Dec 2018
Available at: https://onlinelibrary.wiley.com/doi/full/10.3322/caac.21492
Ref 2 Ref DeSantis CE, Siegel RL et al. Cancer Statistics for African Americans,2016: Progress and Opportunities in Reducing Racial Disparities. 2016: CA cancer J Clin 2016;66:290–308
Ref 3 National Cancer Institute. Surveillance, Epidemiology, and End Results Program. Available at: https://seer.cancer.gov/statfacts/html/prost.html
Ref 4 Le Roux HA et al. Prostate Cancer at a regional hospital in South Africa: we are only seeing the tip of the iceberg. S Afr J Surg Vol. 53 no. 3&4. Dec 2015
Ref 5 Kirby RS, Patel M. Fast Facts: Prostate Cancer. Eight Edition 2014. Health Press Limited
Ref 6 Prostate Cancer UK. Are you at risk? Available at: https://prostatecanceruk.org/prostate-information/are-you-at-risk
Ref 7 Kicin´ski1 M, Vangronsveld J. An Epidemiological Reappraisal of the Familial Aggregation of Prostate Cancer: Available at: www.plosone.org Plos One. October 2011 | Volume 6 | Issue 10 | e27130
Ref 8 Lamy P. Trétarre B et al. Family history of breast cancer increases the risk of prostate cancer: results from the EPICAP study. Oncotarget, 2018, Vol. 9, (No. 34), pp: 23661-23669
Risk Factors for Prostate Cancer
(Compiled July 2018)
(Revised January 2019)
The best known and proven risk factors for prostate cancer are advancing age, race and a positive family history of prostate cancer. There are other risk factors but there is less evidence for these.
Age – As men get older they are more likely to get prostate cancer. The risk for prostate cancer begins to rise sharply after age 55 years and peaks at age 70–74. Global statistics show that three quarters of prostate cancer occur in men over the age of 65 and that prostate cancer is rare in men below the age of 50. However it is important to note that black African men tend to get prostate cancer at a younger age. (See section on race and prostate cancer)
Race – In the USA the risk of prostate cancer is 60% higher in black American men compared to white males. The risk of dying of prostate cancer amongst Black African American men is also twice as high as that of white American men. The current statistics in South Africa are unreliable for a number of reasons but based on the studies from the USA and the UK we believe that black African men are at a much higher risk of getting prostate cancer than other race groups. The type of prostate cancer that they get is also is also likely to be more aggressive and to be passed on genetically.
There is strong evidence to show that a family history of prostate cancer increases a man’s risk of prostate cancer. Men who have a father or brother with prostate cancer are 2 to 3 times more likely to get prostate cancer themselves. The number of relatives with prostate cancer and their age at diagnosis is also important in terms of the likelihood of being affected at a younger age. Some studies show that having a mother or daughter who has had breast cancer also increases a man’s risk for prostate cancer.
Ref: Gann PH., Reviews in Urology. Vol 4, suppl. 5 2002
Other Modifiable Risk Factors for Prostate Cancer
There is strong evidence to suggest that men who have more frequent ejaculations (more than 21 a month), throughout their adult life are about 20% less likely to get prostate cancer. The ejaculations can be from sex, masturbation or nocturnal emissions.
Ref: Rider, Jennifer R. et al. Ejaculation Frequency and Risk of Prostate Cancer: Updated Results with an Additional Decade of Follow-up. European Urology , Volume 70 , Issue 6 , 974 – 982
It is unclear whether smoking increases the risk for prostate cancer. However, there is data that shows that smokers have a 17% greater risk of dying from prostate cancer than non-smokers. Smoking greatly increases the risk of many other cancers so it’s worthwhile for men who smoke to quit.
Ref: Huncharek, Michael et al. Smoking as a Risk Factor for Prostate Cancer: A Meta-Analysis of 24 Prospective Cohort Studies. American Journal of Public Health 100.4 (2010): 693–701. PMC. Web. 20 June 2018.
The relationship between obesity and prostate cancer is a complicated one. It is more difficult to detect prostate cancer in obese men for a number of reasons:
They tend to have lower PSA scores.
They have larger prostates which mean that more cancers are likely to be missed when doctors perform a biopsy.
It is more difficult to perform a digital rectal examination on an obese man
All this means that prostate cancer is less likely to be detected in the early stages in obese men. Obesity is also associated with an increased risk for aggressive prostate cancer and a poorer outcome in men who are treated for prostate cancer. There is strong evidence linking obesity to a number of other serious diseases and for this reason we recommend that obese men get medical assistance to help them get there weight under control.
Ref: Allott, Emma H. et al. Obesity and Prostate Cancer: Weighing the Evidence. European Urology, Volume 63 , Issue 5 , 800 – 809
Dietary factors and prostate cancer
It is important to note that the evidence linking certain foods and vitamins to prostate cancer is not conclusive. We recommend that men follow a diet that has been proven to be good for overall health. Men should also be cautioned about the use of supplements to prevent prostate cancer as there is a possibility that some supplements could increase the risk. The following are some findings that will require additional research before the results can be considered conclusive and recommendations can be made. Please note that the evidence is not currently strong enough for these so we cannot make recommendations.
There is some evidence to show that the regular intake of saturated fats can increase the risk of prostate cancer. Saturated fats are animal fats found mostly mainly in dairy products and red meat.
Meat cooked at high temperatures
There is some evidence to show that eating meat that is well-done or meat that is cooked at a high temperature (e.g. grilled, fried, and barbecued meats) increases the risk for advanced prostate cancer. The more of this type of meat that is eaten the greater the risk.
There is some evidence to show that a diet that is high in calcium increases the risk for prostate cancer.
A diet that includes plenty of fresh fruit and vegetables has strong health benefits and some of the components found in vegetables have antioxidant properties which may help to reduce the risk for cancer.
There is some evidence to show that lycopene can reduce the risk for prostate cancer through its antioxidant effect. Lycopene is a substance that is found in various foods. Foods containing high amounts of lycopene include cooked tomatoes and tomato based products like tomato sauce and tomato paste, guavas, watermelon, grapefruit, papaya, sweet red peppers, asparagus red cabbage and mangoes. However, to obtain significant levels of lycopene from tomatoes products like tomato paste are required as raw tomatoes have very low levels. To illustrate this, one slice of raw tomato contains 515 micrograms of lycopene whilst 2 tablespoons of tomato paste contains 13 800 micrograms. Cooking also alters the lycopene’s molecular structure so that it is more easily absorbed by the body.
Vitamin EThere is some evidence that taking a vitamin E supplement may increase the risk for prostate cancer.
References for Dietary Factors and Prostate Cancer
(1) Gathirua-Mwangi et al. Dietary factors and risk for advanced prostate cancer. European Journal of Cancer Prevention. 23(2):96–109, MAR 2014
(2) Ref: Ford N., Livestrong.com. Accessed on 30/06/2018. Available at: https://www.livestrong.com/article/344493-tomato-cooked-or-raw-lycopene/
(3) Ref: Gann PH. Risk factors for prostate cancer. Reviews in Urology. Vol 4, suppl. 5 2002.
(4) Klein EA et al. Vitamin E and the risk of prostate cancer: Updated results of the selenium and vitamin E cancer prevention trial (SELECT). JAMA. 2011 October 12; 306(14): 1549–1556. doi:10.1001/jama.2011.1437.
Alcohol and Prostate Cancer
There is strong evidence showing that alcohol increases the risk for mouth, throat, oesophageal, liver and colorectal cancer. (1) However the link between alcohol consumption and prostate cancer is less clear and studies have shown conflicting results.
We cannot therefore make recommendations based on the current research.
Some evidence shows that men who are heavy regular drinkers and binge drinkers are at increased risk for prostate cancer whilst non-drinkers may be at increased of dying from prostate cancer compared to those who are light users of alcohol. (2)
Other studies show that alcohol consumption is not associated with overall prostate cancer risk or risk for low-grade prostate cancer but that the risk for high-grade prostate cancer is increased in men who consumed a minimum of seven drinks per week when aged 15 to 19 years compared with men who did not drink during that period of their lives. The same study showed that men with a higher cumulative alcohol intake throughout their lives were more likely to be diagnosed with high-grade prostate cancer. (3)
References for Alcohol and Prostate Cancer:
Ref (1) Testino G, Maedica. A Journal of Clinical Medicine, Volume 6 No.4 2011.
Ref (2) Dickerman A et al. Alcohol intake, drinking patterns, and prostate cancer risk and mortality: A 30-year prospective cohort study of Finnish twins. Cancer Causes Control. 2016 September ; 27(9): 1049–1058. doi:10.1007/s10552-016-0778-6.
Ref (3) Michael J, et. Cancer Prev Res. 2018; Early-Life Alcohol Intake and High-Grade Prostate Cancer: Results from an Equal-Access, Racially Diverse Biopsy Cohort. Available at http://cancerpreventionresearch.aacrjournals.org/content/early/2018/08/16/1940-6207.CAPR-18-0057
Symptoms of prostate cancer
There are generally no symptoms of prostate cancer in the early stages of the disease which is why screening is so important. Some of the symptoms of prostate cancer are the same as the symptoms for an enlarged prostate (benign prostatic hyperplasia or BPH). This condition is also common in older men.
Symptoms in Early (localised) Prostate Cancer
Localised prostate cancer is when the cancer is contained within the prostate. There are generally no symptoms at this stage which is why screening is so important.
Symptoms for locally Advanced Prostate Cancer
At this stage the cancer tumour may have spread to areas surrounding the prostate such as the bladder, the pelvic nerves, the urethra and the seminal vesicles. The tubes carrying the urine (ureters) can be blocked. The following symptoms can occur:
- A need to urinate frequently, especially at night
- An urgent need to urinate
- Difficulty starting urination or holding it in
- Weak or interrupted flow of urine
Blood in the urine or semen
Very little or no urine
When the tumour enlarges it can push against the rectum which sits behind the prostate causing constipation, cramping and rectal bleeding.
Symptoms for Advanced Prostate Cancer (Metastatic Prostate Cancer)
When prostate cancer spreads to other body parts it may cause:
Bone pain particularly in the pelvis and lower spine due to bone metastases (cancer tumours that develop in the bones).
Spinal cord compression causing a loss of feeling in the limbs
Lymph node enlargements
Loin pain due to a blockage in the tubes carrying urine from the kidneys to the bladder
Other symptoms that occur when the cancer is spread widely throughout the body can include:
Lack of energy from iron loss (anaemia)
Weight loss with muscle wasting and loss of appetite
References 1 – Kirby RS, Patel M. Fast Facts: Prostate Cancer. Eight Edition 2014. Health Press Limited
A prostate cancer diagnosis – what now?
Being diagnosed with prostate cancer inevitably comes with a sense of shock and even fear. It can be an overwhelming and confusing time with the overriding question often being “What now?”. First off, take a deep breath or two to assist with keeping the panic at bay. Remember that most prostate cancers are slow growing, meaning that you likely don’t have to make all of your decisions immediately. Take time to consider the following suggestions:
If possible read up on prostate cancer or speak to other prostate cancer patients in order to improve your understanding of the disease as this can be helpful in separating fact from fiction. It is important that you deal with fact. Be aware of “Dr Google” as reading up on medical facts without the requisite medical knowledge can be alarming and confusing.
Prepare for your next doctor’s appointment
Your doctor will likely cover the specifics of the cancer that you have and will undoubtedly tell you about treatment options which could include active surveillance (‘watching and waiting’), surgery, radiation therapy, hormone therapy, chemotherapy or even a combination of these . This can be a lot of information to take in at once so, if possible, have a notepad and pen with you so that you can jot down notes that you can look over later.
If possible take a friend or family member along with you. Not only does this provide you with some support but having another listening ear can also be helpful when there is a lot of information to absorb.
Have a list of questions written down that you would like to ask your doctor. These could include:
- Is the cancer localised or has it spread to other parts of the body (metastatic prostate cancer)?
- Is the type of cancer that I have curable?
- Will further tests be needed? If so, which tests? And who will be available to explain to me what the results mean?
- What are all my treatment options?
- What factors should I consider when choosing a treatment?
- What is your experience with these treatments?
- When can the treatment begin and for how long will it last?
- What are the possible side effects of and/or risks associated with the various treatment options? Could these include incontinence, erectile dysfunction, loss of sex drive, pain? If so, how do I best manage these?
- How will the treatment affect my quality of life?
- If surgery is an option what all does the surgery involve and what would the hospital stay entail?
- Is active surveillance an option for me? If so what does it involve and how often will I need to be checked? What should I be looking out for?
- What if the cancer spreads?
- What other health professionals will be involved in my treatment and care – oncologists, nuclear medicine physicians, psychologists, physiotherapists, anesthaesiologists?
- What outcomes can I realistically expect from a specific treatment option?
Request a copy of all your lab results and any other tests that are done and keep these in a safe place. They are useful to have if you want another opinion and if you do any of your own research. However always speak to your specialist before you reach any conclusions on your own.
Find the right doctor
If you have a private medical aid you should try to find specialists that you are comfortable with and that you feel you can trust. You’re going to see him/her frequently over an extended period of time, you may as well like him and feel a ‘right fit’ with him.
Initially you will probably be referred to a urologist who will make the diagnosis. Depending on how the cancer is going to be treated you may also be referred to an oncologist, a radiation oncologist or even a nuclear medicine physician. Other healthcare professionals like physiotherapists and sexologists might also assist you at different stages of your treatment.
If you have a family doctor/GP they can help you find a specialist.
Seek a second opinion if necessary
Your health and your treatment are your responsibility. If you are not happy with the advice you are receiving from your doctor seek a second opinion. Do not be concerned about possibly offending your doctor, it is your right to seek out the help you feel you need.
Don’t try and do it alone
This can be a scary time and it is important to draw on all the resources and support structures available to you. Talk to someone – whether it be your partner, a friend, a family member or a professional such as a nurse or a counsellor or a psychologist. Share what you are thinking and feeling. You may well be feeling anxious about the future and about the impact of your illness on the relationships with the people close to you. Talking about these things is not a cure but it will definitely help you feel less burdened and will assist you in processing the confusing thoughts and feelings.
You may well find that your loved ones are as confused and anxious as you are. Their personal discomfort and fear might mean that they find it too difficult to even acknowledge your illness, let alone talk about it. They will not necessarily know how to support you. Be direct and honest about what you need from them and how they can help you. Don’t expect them to be able to read your mind.
Join a support group or talk to a prostate cancer survivor
Becoming part of a group of men who are going through a similar experience to you can be tremendously helpful. It provides you with an opportunity to ask questions and express concerns to people who understand exactly what you are going through. If you aren’t able to find a local support group consider joining an online community.
Take care of yourself
Do whatever you can to maintain your health. Explore stress management and relaxation techniques. Eat well, remain as active as possible, and get sufficient sleep. Set your own pace. Yes, you have cancer but try not to allow the diagnosis to define you. Pursue your hobbies and interests and maintain your friendships. Talk about things other than your disease. Set yourself achievable goals, schedule things that you can look forward to.
Seek emotional help if you need it
If you continue to feel overwhelmed and are simply not able to shake anxious and depressive thoughts and feelings, seek help from a professional. Getting help is a sign of strength. It is important to take control of the things that you can take control of.