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10-minute read

What is cancer?

Cancer is a disease of the cells. It happens when abnormal cells in a specific part of the body grow and reproduce in an uncontrolled way. These cancer cells can invade and destroy surrounding healthy tissue, including organs.

Cancer cells can grow in almost any type of cell. So cancer is actually a name for about 100 different diseases.

Sometimes cells that are growing abnormally do not spread. These cells are called ‘benign’, or not dangerous. If the cells spread or are capable of spreading to surrounding areas or to other parts of the body, they are called ‘malignant’ or cancer. The process of cancer spreading to other distant parts of the body is called ‘metastasis’.

Cancer has a significant impact on the Australian community in terms of death, illness and costs.

There are hundreds of different types of cancer, each with its own methods of diagnosis and treatment. The most common cancers in Australia are:

What are the symptoms of cancer?

Early signs of cancer are changes to your body's normal processes or symptoms that are out of the ordinary, like a lump that suddenly appears on your body, unexplained bleeding or changes to your bowel habits.

Usually these changes don’t mean you have cancer. But it’s important you see your doctor so they can investigate.

Potential signs and symptoms of cancer include:

  • lumpiness or a thickened area in your breasts, any changes in the shape or colour of your breasts, unusual nipple discharge, a nipple that turns inwards (if it hasn't always been that way) or any unusual pain
  • a lump in the neck, armpit or anywhere else in the body
  • sores or ulcers that don't heal
  • coughs or hoarseness that won't go away or coughing up blood
  • changes in toilet habits that last more than 2 weeks, blood in a bowel motion or urine
  • new moles or skin spots, or ones that have changed shape, size or colour, or that bleed
  • unusual vaginal discharge or bleeding
  • unexplained weight loss
  • diarrhoea or constipation for no obvious reason
  • a feeling of not having fully emptied your bowels after going to the toilet
  • pain in your abdomen (tummy) or your anus (back passage)
  • persistent bloating

CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.

What causes cancer?

Often we don’t know why cancer happens. But there are some things that significantly increase your risk.

Smoking is responsible for 1 in every 9 cases of cancer and 1 in every 5 deaths from cancer. Drinking alcohol, eating a poor diet, being overweight, not getting enough exercise and being exposed to radiation (such as from sunlight) can also cause cancer.

Sometimes cancer runs in families. You can inherit genes that make you more likely to get cancer.

In other cases, cancer is associated with an infection. For example, cervical cancer is associated with some types of human papillomavirus (HPV) infection. Being exposed to some chemicals and dust can also increase your risk.

When should I see my doctor?

There is a much greater chance of successfully treating cancer if it is detected early. If you notice any changes, see your doctor immediately. For more information, see Cancer Council Australia's early detection fact sheets, or call Cancer Council Helpline on 13 11 20.

How is cancer diagnosed?

Accurately diagnosing cancer can take time. Many cancers grow slowly, and it can be years before they are discovered or cause symptoms. Sometimes cancer is discovered during routine tests or when screening for cancer.

Different tests are used to diagnose cancer. These depend on the location of the problem and your symptoms. Tests may include blood tests, x-rays, CT scans, MRI scans or ultrasounds. Sometimes a doctor may look inside your body with a long tube with a light and camera attached to the end.

If cancer is suspected, your doctor will often take a biopsy, a small sample of tissue that is examined in the laboratory. This will provide information about the type of cancer and how aggressive it is.

How is cancer treated?

There are many different ways to treat cancer. Treatments are improving all the time. The best type of treatment for you depends on the type of cancer and how advanced it is.

Some treatment options include:

  • chemotherapy: powerful cancer-killing medication
  • radiotherapy: the controlled use of high energy x-rays
  • surgery: to remove cancerous tissue
  • immunotherapy: treatment that uses parts of your own immune system to fight the cancer
  • targeted therapy: medication that only targets the cancer, not the other cells in your body
  • hormone therapy: a treatment that uses hormones to stop or slow the cancer’s spread
  • stem cell transplant: also called a bone marrow transplant, to treat some blood cancers
  • palliative care: treatment to enhance your quality of life
  • complementary therapies: therapies like massage and relaxation, to help you cope with treatment

You will see a range of health professionals during treatment. These may include an oncologist, radiologist, surgeon, pathologist, nurses and your own doctor.

You might be invited to take part in a clinical trial. This is a way of testing new treatments and may give you access to treatments that aren’t usually available in Australia.

Can cancer be prevented?

Almost 1 in 3 cancers can be prevented. The best ways to prevent cancer are to:

You can also get checked regularly for some cancers. There are free screening programs available for breast cancer, cervical cancer and bowel cancer.

You can check your risk of cancer by using Cancer Australia’s online risk assessment tools.

Complications of cancer

Unfortunately, people who have had one cancer are more likely to get a second cancer, which may be the same or different to their first cancer. Chemotherapy and radiotherapy further increase this risk, but it will have been considered carefully when your initial treatment is planned. Following a healthy lifestyle will help to protect you from developing another cancer.

Some cancers raise certain proteins or other substances in your blood, called tumour markers. However, The Royal College of Pathologists of Australasia recommends that you ask your doctor or specialist about the benefits and downsides of testing for tumour markers and whether it is relevant to your situation. For further information, visit the Choosing Wisely Australia website.

Resources and support

If you’ve been diagnosed with cancer, it’s normal to feel shocked, sad, angry or worried. There is plenty of support for you (see below). It’s a good idea to look after yourself by keeping active, eating a nutritious diet, talking to your doctor for help to manage pain or sleep problems, and managing your finances and other affairs.

The Cancer Council can give you advice on how to tell other people, including children.

Rare Cancers Australia has a knowledge base that contains information about rare cancers, including specialised cancer services, support services and clinical trials.

Your doctor or specialist may be able to reassure you if you have questions, or you may find it helpful to talk to a trained counsellor, psychologist or call specialist helplines.

Patient organisations have local groups where you can meet other people who have been diagnosed with cancer and have had treatment.

If you have feelings of depression, talk to your doctor who will be able to provide advice and support.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: February 2020

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