Cancer is abnormal cell growth. It is the most common cause of death in Victoria, accounting for more than 10,500 deaths every year. There are about 200 different types of cancer and most areas of the body can be affected.
Some cancers can be prevented by avoiding risk factors. For others, early detection and treatment is the best way to improve your chance of cure.
Cancer is abnormal cell growth
Generally, cancer happens when the normal cells in our body grow in an uncontrolled way. Our bodies are made up of billions of different types of cells. We are always making new cells. This enables us to grow, replace worn out cells and heal damaged cells after an injury. Special genes make sure the new cells develop and behave the way they should.
If these genes are damaged, our cells can multiply fast and grow abnormally. This abnormal cell growth may turn into a cancer. If cancer cells replace too many healthy cells, the affected organ can no longer work properly.
Where cancers start
Cancers can start in any part of the body. They have different names depending on where they start. For example:
- Carcinomas – start in the cells that line the skin and body cavities.
- Sarcomas – grow within supportive tissues of the body such as muscle, bone and fatty tissue.
- Leukaemia – is one type of cancer that develops in the tissue where white blood cells are formed, called the bone marrow, and affects the cells in the blood.
- Myeloma – develops in the plasma cells.
- Lymphoma – begins in the cells of the lymphatic system.
Tumours explained
A tumour is a lump or growth of abnormal cells. It can be benign (not cancerous) or malignant (cancerous). A benign tumour is made up of cells that are similar to normal cells. They do not cause problems unless they grow very large and begin to press on other organs in the body. Malignant tumours are made up of cancer cells and they usually grow much faster than a benign tumour. If left untreated, they may spread into surrounding tissue and to other parts of the body.
How cancers spread
A cancer begins to spread when part of the original tumour (primary tumour) breaks away from where it started and travels to nearby tissue or another part of the body. The cancer cells then start to grow there. A malignant tumour that spreads its cells into nearby tissues is known as an invasive cancer. When a cancer spreads from one part of the body to another, it is known as a secondary cancer or ‘metastasis’.
For a cancer to grow bigger than a pinhead and spread, it has to grow its own blood supply. This is called angiogenesis. Without this, the cells at the edge of the tumour will die from lack of oxygen.
Cancer cells produce substances that allow them to move through the body much more easily than normal cells. Also, cancer cells do not stick together as well as normal cells. A cancer can spread in three main ways:
- Locally, in and near the tissue around the primary cancer
- Through the lymphatic system
- Through the blood circulation.
Cancers are ‘staged’
Staging means working out the size of the cancer and how far the cancer has spread. Knowing the stage of a cancer helps medical professionals decide on the best treatment. There are various ways to stage cancer, but most systems look for a number of key factors including:
- The size of the cancer
- If the cancer has invaded nearby tissues and by how much
- If the cancer has spread to nearby lymph vessels and by how much
- If the cancer has spread to other parts of the body.
Risk factors
The exact cause of most cancers is unknown and there is no one cause for any type of cancer. Some risk factors are likely to cause cancer, whereas others will only slightly increase the likelihood of developing cancer. This may be a combination of genetic and environmental factors.
Some risk factors include:
- Age – most types of cancer become more common as we get older.
- Genetic make-up – some people are born with a genetic mutation that already puts them at risk of developing a cancer.
- Family history – a changed gene is passed on from parent to child.
- Lifestyle choices – such as diet, smoking, high alcohol intake and lack of physical activity.
- Environmental causes – such as exposure to too much natural radiation from the sun or radon gas.
- Exposure to harmful chemicals in the workplace – such as some dyes, rubber, gas and asbestos (now banned in Australia).
- Man-made radiation.
- Viruses – specific viruses can help to cause some cancers but you cannot catch them like an infection.
- Your immune system – people who have problems with their immune system are more likely to get some forms of cancer.
Screening can help detect some cancers early
A person with cancer may not show any symptoms until the disease is advanced. Screening a section of the population for a cancer is done if:
- The disease can be recognised at an early stage
- There is an effective low-risk and low-cost screening test
- Early treatment is likely to give a better outcome.
Three national population-screening programs operate in Victoria:
- BreastScreen Victoria
- National Cervical Screening Program
- National Bowel Cancer Screening Program.
See the Where to get help section of this fact sheet for more information about these services.
Treatment
There are three main types of standard treatment used in cancer care. Each one can be used to try and cure cancer, to relieve symptoms, to help other treatments work better or to improve survival.
- Surgery – the cancer is surgically removed. This is often the first line of treatment if the cancer has not spread. It may be used to remove lymph nodes if these are also affected by the cancer. Cancers of the blood system (such as leukaemia) cannot be treated with surgery.
- Chemotherapy – the use of cancer-killing drugs. There are many different types of chemotherapy drugs. Some are given as tablets or capsules but most are given by drip (infusion) into a vein. The drugs go into the bloodstream and travel throughout the body to treat cancer cells wherever they are.
- Radiation therapy (or radiotherapy) – small, precise doses of radiation target and destroy cancer cells. Cancers that have not spread can often be treated effectively with radiation therapy.
You may be given one of these treatments alone or a combination of all three. There are other treatments, such as hormone therapy and immunotherapy (biological) therapy, which may be given for certain types of cancer.
Sometimes a cancer is diagnosed when it is very advanced. This may mean that standard treatment is not going to cure the cancer. When a cure is unlikely, chemotherapy, radiotherapy or other treatments can relieve symptoms and help the person feel as comfortable as possible. They may also prolong life. This is called ‘palliative treatment’.
Some people may look at using complementary and alternative cancer treatments. When used alongside your conventional cancer treatment, some of these therapies can make you feel better and improve quality of life. Others may not be so helpful and in some cases may be harmful. You may like to read the Cancer Council Victoria’s booklet Complementary and alternative cancer therapies.
Remission means the cancer is controlled
Cancer that responds to treatment either stops growing or starts to shrink. This means that the signs and symptoms of cancer disappear. Doctors call this ‘remission’. A remission can last anywhere from months to years.
About cancer statistics
It is important to remember that statistics are very general and they are only used as a general guide. The three most common groups of statistics used to talk about cancer are:
- Incidence – the number of people who develop a certain type of cancer each year.
- Survival – refers to how long you may survive a cancer depending on the type of cancer, your age, the stage of the cancer and the treatment you had. They are usually written as ‘5’ and ‘10’ year survival rates. ‘Five-year survival’ and ‘10-year survival’ refers to the percentage of people who are living 5 or 10 years after their diagnosis with a certain type of cancer. Some patients may be cured but for others the cancer will come back (recur) in this 5-year period. Others may go on for many more years before the cancer comes back.
- Mortality – this is the number of people who have died from a particular type of cancer in a year.
Incidence and mortality rates can vary between different groups of people. Some of these variations include:
- Socioeconomic differences – lung cancer and stomach cancer are more common in lower socioeconomic groups, while breast and prostate cancer and melanoma are more common in higher socioeconomic groups.
- Geographic differences – the male death rate from lung cancer is 25 per cent higher in rural compared with metropolitan areas of Victoria.
- Birthplace differences – people born overseas have lower death rates from some cancers and higher death rates from others depending on the country of origin. This is probably due to differences in lifestyle factors such as smoking, sun exposure and diet.
Where to get help
- Your doctor
- Cancer Council Helpline, Tel. 13 11 20
- Multilingual Cancer Information Line, Victoria Tel. (03) 9209 0169
- BreastScreen Victoria
- National Cervical Screening Program
- National Bowel Cancer Screening Program
- Cancer Council Victoria’s booklet Complementary and alternative cancer therapies
Things to remember
- Cancer is a disease of the body’s cells and is caused by changes to some genes that control how cells behave.
- There are around 200 different types of cancer and most areas of the body can be affected.
- Cancers differ in their cause, early symptoms and signs, treatment and outcome.
- The earlier a cancer is found the easier it is to treat.
