Cancer begins with an alteration to the coding information in cells that tells them when to grow and replicate. The code is read from the deoxyribonucleic acid (DNA) that is found in all human cells. A change in the code is called a mutation and can alter the instructions that control cell growth.
If a mutation occurs, the cells carry on growing instead of stopping when they should. The cells reproduce in an uncontrollable manner, producing a lump of tissue that is known as a tumour.
How cancer spreads
Left untreated, cancer can quickly grow and spread to other parts of your body. There are two ways that breast cancer can spread:
- directly – where the cancer spreads outs of the breast tissue into surrounding muscle and skin
- indirectly – where cancer cells spread via the blood or lymphatic system (see below) to more distant parts of the body, such as the lungs and liver
The lymphatic system is a series of glands (or nodes) that are distributed throughout your body in a system that is similar to the blood circulation system. The glands produce many of the specialised cells that are needed by your immune system.
Risk factors for breast cancer in men
It is not clear exactly what causes the DNA inside the cells of the male breast to behave in this manner. However, a number of risk factors that can increase your risk of breast cancer developing have been identified (see below).
Due to the rarity of breast cancer in men, even if you had most of the risk factors outlined below (with the exception of having Klinefelter’s syndrome), your risk of developing the condition would still be very small.
Genetics and family history
A genetic mutation is where the instructions that are carried in all living cells become scrambled in some way which means that one or more of the body’s processes do not work in the way they should.
There are a number of genetic mutations known to increase your risk of developing breast cancer. The most significant mutation identified to date is known as the BRAC2 mutation. One study that was carried out in the UK found that 1 in 20 men with breast cancer have the BRAC2 mutation.
There is also evidence that breast cancer can run in families, as 1 in 5 men who develop breast cancer, have a first-degree relative, such as a mother or sister, who also has a history of breast cancer.
Oestrogen exposure
There is evidence that prolonged exposure to the hormone oestrogen can increase the risks of breast cancer in men.
Compared to women, men tend to have low levels of oestrogen, but there are a number of circumstances that can increase the levels of oestrogen in men.
These include:
- hormone treatments – man-made (synthetic) versions of oestrogen are often used to treat prostate cancer and are also given to transsexuals who are undergoing a male to female sex change
- obesity – obese men have higher levels of oestrogen than normal
There is also rare genetic condition called Klinefelter’s syndrome where baby boys are born with much higher levels of oestrogen than normal. It is estimated that 1 in every 1,000 people are affected by Klinefelter’s syndrome.
Klinefelter’s syndrome is a major risk factor for breast cancer in men. Men who have the condition are 20 times more likely to develop breast cancer than the male population at large.
Occupational risks
There is evidence that men who work in hot environments are twice as likely to develop breast cancer compared with men who work in cooler environments. Environments that have been linked to an increase risk of breast cancer in men include:
- blast furnaces
- steel works
- rolling mills – a factory where metal (usually steel) is shaped using rollers
- car manufacturing plants
One theory to help explain the link between working environment and the increased risk of developing breast cancer is that excessive heat may damage the testicles, which could lead to an increase in oestrogen levels.
Another theory is that working in hot environments usually involves exposure to certain chemicals which may increase a the risk of developing breast cancer in men.
Rates of breast cancer are also unusually high in men who manufacture perfumes and soaps.
They are seven times more likely to develop breast cancer than the male population at large. The reason for this increased risk is still unclear, although exposure to certain chemicals seems to be an obvious, although as yet unproven, factor.
Radiation
Exposure to radiation has been linked to an increased risk of developing breast cancer in men.
Research has found that men who received a course of radiotherapy (where high energy X-rays are used to kill cancerous cells) directed at the upper chest were seven times more likely to develop male breast cancer compared to the population at large.
However, it is important to put the increase risk in context. Even a seven-fold increase means that the chances of developing breast cancer is still very low at around 1 in 14,285.
Glossary
Chromosome:Chromosomes are the parts of a body cell that carry genes. A human cell usually has 23 pairs of chromosomes.
Testicles:Testicles are the two oval-shaped reproductive organs that make up part of the male genitals. They produce sperm and sex hormones.
Liver:The liver is the largest organ in the body. Its main jobs are to secrete bile (to help digestion), detoxify the blood and change food into energy.
Genetic:Genetic is a term that refers to genes- the characteristics inherited from a family member.
Lung:Lungs are a pair of organs in the chest that control breathing. They remove carbon dioxide from the blood and replace it with oxygen.
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Causes of breast cancer in men
