Cancer
Cancer begins with an alteration to the structure of the DNA that is found in all human cells. This is known as a genetic mutation. The DNA provides the cells with a basic set of instructions, such as when to grow and reproduce.
The mutation in the DNA changes these instructions so that the cells carry on growing. This causes the cells to reproduce uncontrollably, producing a lump of tissue known as a tumour.
How cancer spreads
Most cancers grow and spread to other parts of the body through the lymphatic system. The lymphatic system is a series of glands (or nodes) that are located throughout your body in a similar way to the blood circulation system. The lymph glands produce many of the specialised cells that are needed by your immune system (the body’s natural defence against disease and infection).
Left untreated, testicular cancer will first spread into nearby blood vessels and lymph nodes. Over time, the cancer can spread through the lymphatic system into other parts of the body, such as the lungs, liver, bones and brain.
Risk factors
It is not known what triggers the onset of testicular cancer. However, research has identified a number of factors which may increase your chances of developing the condition. Some of these risk factors are outlined below.
Undescended testicles
The medical name for undescended testicles is cryptorchidism. When male babies grow in the womb, their testicles develop inside their abdomen. The testicles then normally move down into the scrotum when the baby is born or during their first year of life.
However, for some children, the testicles fail to descend into the scrotum. Surgery is usually required to move the testicles down. If you have had surgery to move your testicles down into your scrotum, your risk of developing testicular cancer may be increased.
One study found that if surgery is performed before the child is 13 years of age, their risk of later developing testicular cancer is approximately double that of the rest of the population. However, if the operation is carried out after the boy is 13 years of age, the risk of developing testicular cancer is five times greater than that of the rest of the population.
Age and race
Unlike most other types of cancer, testicular cancer is more common in young and middle-aged men than in older or elderly men. It most commonly affects men between 20 and 44 years of age, with 90% of testicular cancer cases affecting men under the age of age 55.
Testicular cancer is more common in white men than other ethnic groups. It is also more common in northern and western Europe compared with other parts of the world.
Family history
Having a close relative with a history of testicular cancer increases your risk of developing it.
If your father had testicular cancer, you are four to six times more likely to develop it than a person with no family history of the condition. If your brother had testicular cancer, you are eight to ten times more likely to develop it (having an identical twin with testicular cancer means that you are 75 times more likely to develop it).
The fact that testicular cancer appears to run in families has led researchers to speculate that there may be one or more genetic mutations (abnormal changes to the instructions that control cell activity) that make a person more likely to develop testicular cancer.
A promising piece of research that was carried out in 2009 identified mutations in two genes (known as the KITLG and SPRY4 genes) that appear to increase the risk of a person developing testicular cancer.
Testicular dysgenesis syndrome
Over the last 20 years, rates of testicular cancer have doubled, both in England and in other western countries. Rates of three other conditions that affect the male genitals have also been increasing. These are:
- low sperm count
- undescended testicles
- hypospadias, where the urethra (the tube in the penis through which urine passes) is not located in the correct position
Some researchers believe that these conditions, as well as testicular cancer, are interrelated and that, rather than being separate conditions, they are all different forms of a single underlying syndrome. This syndrome has been given the name testicular dysgenesis syndrome (TDS).
If TDS exists, it may be caused by exposure to chemicals during pregnancy that disrupt the normal balance of hormones. This may interfere with the normal development of the male genitals, increasing the chances of the cells of the testicles becoming more cancerous.
Chemicals that are known to disrupt hormonal balance are called endocrine disruptors.
Endocrine disruptors
Examples of endocrine disruptors include:
- some types of pesticide
- polychlorinated biphenyls (PCBs), chemical compounds used as a coolant
- dibutyl phthalate, a chemical used to manufacture cosmetics, such as nail polish
In most countries, including the UK, many endocrine disruptors, such as PCBs, have been withdrawn as a result of their link to health problems. However, there is a concern that exposure to endocrine disruptors may still occur due to contamination of the food chain.
The World Health Organization (WHO) has carried out extensive research to find out whether exposure to endocrine disruptors is responsible for the rise in conditions that affect the development of the male genitals and whether it causes infertility.
Researchers have concluded that direct exposure to high levels of endocrine disruptors can have an adverse affect on human health and male fertility.
However, as yet, there is not yet enough evidence to prove that there is a definite link between indirect exposure to low levels of endocrine disruptors and health problems. Indirect exposure is the type of exposure that would occur if the food chain was contaminated.
Infertility
Men who are infertile are three times more likely to develop testicular cancer than fertile men. It is uncertain whether this is due to testicular dysgenesis syndrome (as mentioned above) or another underlying cause.
Smoking
Research has found that long-term smokers (people who have been smoking a pack of 20 cigarettes a day for 12 years or 10 cigarettes a day for 24 years) are twice as likely to develop testicular cancer than non-smokers.
Height
A study that was carried out in 2008 found that a man’s height affects his chances of developing testicular cancer.
Men who are 190-194cm (6.1-6.3ft) tall are twice as likely to develop testicular cancer than men of average height. Very tall men, who are 195cm (6.4 ft) or above, are three times more likely to develop testicular cancer than men of average height.
Being shorter, less than 170cm (5.6ft) tall, decreases your risk of getting testicular cancer by around 20%.
The researchers who conducted the study have argued that the link between height and cancer risk may be caused by diet. Taller children often require a higher-calorie diet as they are growing up, and it may be the effects of such a diet that leads to the increase in cancer risk.
