How does cancer begin?
Cancer begins with an alteration to the structure of the deoxyribonucleic acid (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.
However, the mutation in the DNA changes these instructions, so that the cells carry on growing. This causes the cells to reproduce in an uncontrollable manner, producing a lump of tissue that is known as a tumour.
How does cancer spread?
Left untreated, cancer can grow and spread to other parts of the body, usually via the lymphatic system.
The lymphatic system is a series of glands (or nodes) that are spread throughout your body, much like your blood circulation system. The lymph glands produce many of the specialised cells that are needed by your immune system.
Once the cancer reaches the lymphatic system, it is capable of spreading to any other part of your body, including your bones, blood, and organs.
Risk factors
It is not known for certain what causes the cells in the breast to become cancerous. However, a number of risk factors for male breast cancer have been identified. These are discussed below.
Genetic mutations
A genetic mutation is when the normal instructions carried in certain genes become ‘scrambled’. Parents can pass on specific genetic mutations to their children.
A number of mutated genes have been linked to an increase risk of male breast cancer. For example, a mutation known as the BRAC2 mutation has been found in an estimated 5% of men with male breast cancer.
There is also evidence that male breast cancer can run in families, as 1 in 5 men who develop breast cancer, have a first-degree male relative, such as a father, or brother, who also has a history of breast cancer.
Oestrogen exposure
Oestrogen is a hormone that contains powerful chemicals, which can have a wide range of effects on different areas of the body. There is evidence that prolonged exposure to oestrogen can increase the risks of male breast cancer
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 - 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, and
- 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.
Klinefelter's syndrome is a major risk factor for male breast cancer because men with the condition are 20 times more likely to develop male 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 male breast cancer compared with men who work in cooler environments. Working environments that have been linked to an increase risk of male breast cancer include:
- blast furnaces,
- steel works,
- rolling mills - a factory where metal (usually steel) is shaped using rollers, and
- car manufacturing plants.
One theory to explain the link between working environment and the increased risk of developing male 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 the risk of male breast cancer.
Rates of male 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, but exposure to certain chemicals seems to be an obvious, although as yet unproven, factor.
