What is the cancer

What is cancer?
Your body is made up of billions of cells that can only be seen under a microscope. These cells are grouped together to make up the tissues and organs of our bodies. They are a bit like building blocks.



Genes and cancer
There are many different types of cells in the body which do different jobs, but they are basically similar. They all have a centre called a nucleus. Inside the nucleus are the genes. Genes are really bits of code. The information they carry can be switched on or off. The genes control the cell. They decide when it will reproduce, what it does and even when it will die.



Normally the genes make sure that cells grow and reproduce in an orderly and controlled way. If the system goes wrong for any reason, the usual result is that the cell dies. Rarely, the system goes wrong in a way that allows a cell to keep on dividing until a lump called a 'tumour' is formed.

Benign and malignant tumours
Tumours (lumps) can be benign or malignant. Benign means not cancer. Benign tumours
• Usually grow quite slowly
• Do not spread to other parts of the body
• Usually have a covering that is made up of normal cells
Benign tumours are made up of cells that are quite similar to normal cells. They will only cause a problem if they
• Grow very large
• Become uncomfortable or unsightly
• Press on other body organs
• Are taking up space inside the skull
• Release hormones that affect how the body functions
Malignant tumours are made up of cancer cells. They
• Usually grow faster than benign tumours
• Spread through and destroy surrounding tissues
• Spread to other parts of the body


Animated Version of Diagram

It is the ability to spread that makes a cancer dangerous. If a cancer is not treated, it can threaten the organs near to where it started growing. It can also damage other parts of the body by spreading.


Primary and secondary cancer

The place where a cancer begins is called the 'primary cancer'. But the cancer cells can spread. They can break away and are carried in the blood or lymphatic system to other parts of the body. There they can start to grow new tumours. Cancers can also spread to nearby body tissues. For example, lung cancer can spread to the lining of the chest, the pleura. Ovarian cancer can spread to the lining of the abdomen (the peritoneum). Tumours from cancers that have spread are called 'secondary cancers'. Doctors sometimes call these metastases and say a cancer that has spread has 'metastasised'.

The various organs of the body are made up of different types of cells. Any of these cell types can grow into a primary cancer. Cancers from different cell types behave differently.

They can
• Grow at different speeds
• Have various effects on the body by releasing chemicals into the blood
• Be more or less likely to spread in the blood
• Respond differently to drugs
• Respond differently to radiation
Cancers can cause different symptoms in different people because of where they are. A cancer may press on a nerve, or another body organ that is nearby. The place where the cancer starts also affects what treatment can be used because doctors have to take into account the risk of damaging neighbouring organs.


How cells and tissues grow

Body tissues grow by increasing the number of cells that make them up. The cells reproduce themselves exactly. One cell doubles by dividing into two. Two cells become four and so on.

This happens very fast between conception and adulthood. But once we are grown up, cells normally only reproduce in order to replace others that have died, for example through injury or illness.
Can all cells reproduce?

Not all cells carry on being able to reproduce. Most cells mature and become specialised for their particular job in the body. Mature cells may lose the ability to reproduce as they develop. But there will always be enough immature cells around (called stem cells) to replace cells that are damaged or killed.
How cells reproduce

When more cells are needed by the body, some cells double up to increase their numbers. They do this very precisely so that the new cells are exactly the same as the old ones. Each cell makes copies of all its genes. Then it splits into two with one set of genes in each new cell.
If even more cells are needed, these new cells will rest for a while and then reproduce again. The cells will carry on doing this until enough cells have been made.
How do the cells know when to stop growing?

Normal growth and healing is very orderly and precise. The cells somehow know when there are enough new cells to mend a cut or stop a finger growing for ever.

Scientists are still finding out how the cells do this. It seems that the cells send chemical messages to each other. The messages come from the genes inside the cells. Just to make sure, there are some genes that become activated and tell cells to reproduce and other genes that tell them not to.


How do new cells end up in the right place?

Why does a growing finger end up finger shaped? It seems the cells have a natural ability to stick together in the right place. Scientists call this cell adhesion.
There are molecules on the surface of the cell which match its neighbours'. It is a bit like having a postal code. The code makes it very difficult for the cell to move to the wrong place. But if it does find itself in a place where its postal code is different from its neighbours' code it will die.
Can cells carry on doubling for ever?

No they can't. It seems human cells are pre-programmed to reproduce up to 50 or 60 times maximum. Then they will eventually die. Stem cells provide a pool of dividing cells that the body uses to restock. Other things can cause the cell to self destruct before it gets as far as doubling 60 times. If the genes of a cell are very badly damaged, or if it becomes detached from its proper place as explained above, it will commit suicide. This self destruction is called 'apoptosis'. Scientists are doing a lot of work on apoptosis at the moment. If the scientists can understand what makes a cell self destruct, they might be able to use this to develop cancer treatments further.
Are cancer cells like normal cells?
• No, they are different in a very important number of ways

The cancer cell

Normal cells have a number of important characteristics. They can
• Reproduce themselves exactly
• Stop reproducing at the right time
• Stick together in the right place
• Self destruct if they are damaged
• Become specialised or 'mature'
Cancer cells are different to normal cells in several ways. These are some features of cancer cells
• They carry on reproducing
• They don't obey signals from other neighbouring cells
• They don't stick together
• They don't become specialised, but stay immature
• They don't die if they move to another part of the body

Cancer cells don't stop reproducing

Unlike normal cells, cancer cells do not stop reproducing after they have doubled 50 or 60 times. This means that a cancer cell will go on and on and on doubling. So one cell becomes two, then four, then eight, then sixteen....

The cancer cells may be more resistent to self destruction than normal cells, or they may self destruct more slowly than they reproduce. Eventually a tumour is formed that is made up of billions of copies of the original cancerous cell. Scientists describe cancer cells as being 'immortal'.
Cancer cells do not obey signals

Something in the cancer cells overrides the normal signalling system. This may be because the genes that tell the cell to reproduce keep on and on firing. Or because the genes that normally tell the cell to stop reproducing have been damaged or lost. So the cancer cell keeps on doubling up regardless of the damage it causes to the part of the body where it is growing.
Cancer cells do not stick together

Cancer cells can lose the molecules on their surface that keep normal cells in the right place. So they can become detached from their neighbours.

This partly explains how cancer cells spread to other parts of the body.
Cancer cells do not become specialised

Unlike normal cells, cancer cells do not carry on maturing once they have been made. In fact, the cells in a cancer can become even less mature over time. With all the reproducing, it is not surprising that more of the genetic information in the cell can become lost. So the cells become more and more primitive and tend to reproduce more quickly and even more haphazardly.
Grade

You may hear your doctor talk about the 'grade' of your cancer. This means how well developed or mature the cell looks like under the microscope. The more the cancer cell looks like a normal cell, the more it will behave like one
• The more normal a cancer cell looks, the lower its grade.
• The more abnormal or less well developed a cancer cell is, the higher its grade.
Your doctor may call this 'differentiation'. Cells can be well differentiated, moderately differentiated, or poorly differentiated. This is the same as low, medium or high grade. Other doctors may talk about grades 1, 2, or 3, where grade 1 is low grade.

Although there are many different ways of talking about this, it all comes down to the same thing. A low grade cancer is likely to be less aggressive in its behaviour than a high grade one. Doctors cannot be certain how the cells will behave. But grade is a useful indicator. Grade is one of the factors doctors use to decide on treatment with some types of cancer

Genes and mutation

Genes are coded messages inside a cell that tell it how to behave. The genes are codes that tell the cell how to make many different proteins


What causes cancer?

This is not as simple a question as it sounds because
• There are many different types of cancer
• More than one 'cause' is often involved
There are about 200 different types of cancer affecting the different body tissues. What affects one body tissue may not affect another. For example, tobacco smoke that you breathe in may help to cause lung cancer. Over exposing your skin to the sun could give you a melanoma on your leg. But the sun won't give you lung cancer and smoking won't give you melanoma.

Apart from infectious diseases, most illnesses are 'multi-factorial'. And cancer is no exception. Multi-factorial means that there are many factors involved. In other words, there is no single cause for any one cancer. These are some of the factors involved in getting a cancer
• Age
• Your genetic make up
• Your immune system
• Your diet
• Your day-to-day environment
• Viruses
A 'carcinogen' is something that can help to cause cancer. Tobacco smoke is a powerful carcinogen. But not everyone who smokes gets lung cancer. So there must be other factors at work.

About diet

It is thought that these foods are protective against cancer
• Fibre
• Vitamins A, C, E and D
• Certain types of oils found in fish
and these foods are risk factors for cancer
• Fats (especially animal fats)
• Meat
• Alcohol
But it is a complicated picture. It does not seem to be enough to take vitamin supplements for example. There is something about eating fresh vitamin rich foods that is protective.

An international research study is going on at the moment across Europe to try to answer more questions about diet and cancer. The study, called EPIC, involves 500,000 people in 10 countries. EPIC stands for European Prospective Investigation into Cancer and Nutrition. The researchers are looking into the food intake of those taking part over many years. They are also monitoring these people's health records and recording who gets cancer and who doesn't. Then they may be able to link certain factors in the diet with the risk of getting particular cancers. It is the largest study into diet and cancer ever conducted.

The results of EPIC could have huge implications for the prevention of cancer. To start with, the researchers are looking into common cancers such as breast, lung, colorectal, prostate and stomach cancer. But the size of this study means that researchers will also be able to look into the possible role of diet in rarer cancers. The results of the study will have implications for cancer prevention everywhere. The results will be presented at international conferences and published in journals available to researchers and health officials throughout the world.

Food additives and cancer
There are many different substances added to commercially prepared foods. But these are not all bad. Some additives stop food from going off and so can help to keep us healthy. A good example of this is a toxin called aflatoxin that comes from a mould. It grows on stored food in hot and humid countries, especially on peanuts. This is known to help cause liver cancer so anything that stops the mould from getting into the nuts is helping to prevent cancer.

Most additives are not thought to affect cancer risk. Colours, flavours and sweeteners are constantly investigated by researchers and if any are thought to be a real risk, they may be withdrawn. Sometimes there is a scare about a particular additive. Some years ago saccharin was claimed to be a carcinogen.

Researchers had found that when it was fed to rats in huge quantities, the rates of cancer in the rats increased. We are very unlikely to eat so much saccharin and so it is unlikely to cause cancer in people, but far fewer foods contain it now than did a few years ago.

Other additives can be a cancer risk. Pickled foods may increase risk of cancer of the stomach and oesophagus (gullet), particularly if they are very salty. This may explain why there are such high rates of stomach and oesophageal cancer in Japan, where salty pickled foods are popular.

Smoking and barbecueing foods increases the amount of polycyclic hydrocarbons in foods. There has been some research suggesting that these chemicals could increase the risk of developing stomach and oesophageal (gullet) cancer. So while barbecued food is very tasty, you may think it is best not to eat it too often.
Contaminants
This means chemicals in foods or drinks that are not meant to be there. They could form as a by-product of the manufacturing process, for example.

Nitrosamines are chemicals found in cured meats (bacon and ham, for example) and beer. Nitrosamines have been shown to be carcinogenic so the amount in foods has been cut as much as possible. In brewing, one cause of nitrosamines is a reaction between pollution in the atmosphere and the malted barley that is one of the main ingredients of the beer. The brewing industry has tried to cut the levels of nitrosamines in beer as much as possible. Levels are now much lower than they used to be, but it hasn't been possible to get rid of them completely.
Obesity and cancer

'Obese' means more than about 25% overweight. It is measured by comparing your weight with your height. Click on the link to find out how to work this out accurately. Obesity can increase your risk of
• Breast or uterine (womb) cancer if you are a woman
• Prostate cancer if you are a man
• Colon (bowel) or rectal cancer
Researchers do not know much about how much the risks increase, or exactly why. Prostate and breast cancer are hormone linked. Their development is affected by amounts of the sex hormones oestrogen and testosterone. Fatty tissue produces an enzyme called 'aromatase'. Aromatase affects the balance between these hormones and this may explain why being obese affects your risk of prostate or breast cancer. Obese people may have increased risk of bowel cancer because they eat too much animal fat in their diets.
A healthy diet

The diet thought to help reduce cancer risk is much the same as that recommended for a healthy heart. So you really can make a difference to your health if you
• Eat less meat and animal fats (butter, cream, cheese)
• Eat five portions of raw or lightly cooked fruit and vegetables every day (5 portions is about 400g or 1lb in weight)
• Eat more fibre
• Eat more oily fish (eg salmon, trout, mackerel)
• Eat less salt, salty foods, sugar and sugary foods
• Eat more cereals, bread, pasta and rice
• Don't fry foods and if you use fats in cooking, choose vegetable oils or olive oil not lard or butter
• Drink less alcohol

About Cancer Treatment
The tratment of cancer related to type of cancer and this type of some treatmen:
Surgery
Chemotherapy
Radiotherapy
Bone marrow and stem cell transplants
Immunotherapy
Hormone therapy
Gene therapy
Cancers sometimes come back

Chemotherapy
Chemotherapy is treatment with anti-cancer drugs. Chemotherapy can be used
• To shrink a cancer before surgery
• To reduce the risk of a cancer coming back after surgery
• Along with radiotherapy
• By itself to cure a cancer
• To control symptoms and improve quality of life when a cancer is too advanced to cure
The effect of chemothererapy on person:

• Not being able to have a baby or father a child (infertility)
• Fatigue
• Lowered resistance to infection
• Damage to body organs
• Increased risk of getting another type of cancer
• Depression
• Changes in your concentration and memory
• Cataracts

About your environment

We don't always know what causes a particular cancer. Most often there is more than one cause. But research is going on all the time into possible causes so that in the future as many cancers as possible can be prevented.

• Tobacco
• The sun

• Place of work

• The radiation: