Cancer: the basics
Cancer can be life-threatening depending on its type and stage, but survival rates for many cancers are improving because of better screening and treatment. Cancer is the uncontrolled growth of abnormal cells. These cells can grow into a mass called a tumour, and may infiltrate and destroy normal body tissue.
This process can occur in almost any tissue of the body. Usually, cancer will require uncomfortable treatment, but the positive aspect of this is that there are more successful treatments available now than ever before.
In 2013, about 125,000 Australians will be diagnosed with cancer. The disease accounts for three out of every 10 deaths in the country, and is a growing cause of death worldwide. However, survival rates for many cancers are improving because of better screening and treatment. Having regular screening tests and diagnosing cancers as early as possible is crucial in the ongoing fight against this disease.
“Benign” and “malignant”
Tumours are either benign or malignant:
- Benign tumours are not cancerous and do not spread to other parts of the body. They can cause problems by pressing on nearby organs, and some may become cancerous if untreated.
- A malignant tumouris made up of cancer cells and may invade surrounding tissues. If cancerous cells move away from the original (primary) cancer and spread to other organs, this is called a secondary cancer or metastasis.
What causes cancer?
The causes of many cancers are not yet known. Several elements may work together to trigger the disease.
To allow us to grow, and to replace old and damaged cells, our bodies constantly make new cells. Cancer is caused by mutations in the genes controlling this process. Various gene mutations may cause cells to divide too rapidly or in an uncontrolled way, or create mistakes in DNA repair.
Many cancers have been linked to unhealthy lifestyle habits, such as smoking, bad diet, sun exposure, excessive drinking and unsafe sex. Other factors that are known to increase cancer risk include:
- Exposure to environmental carcinogens (cancer-causing substances), eg. second-hand smoke, asbestos, benzene.
- Age. Cancer can take a long time to develop. While it can occur at any age, most people diagnosed are over 65.
- Family history. In rare instances, people are genetically predisposed to certain cancers. Genetic testing can reveal inherited mutations.
- Health and bodily condition.Mutations can be caused by hormones, viruses or chronic inflammation. Particular medical conditions, such as ulcerative colitis, also increase the risk of certain cancers.
Symptoms to look out for
Symptoms depend on the type and location of the tumour, but may include:
- Fevers, night sweats
- Unintentional weight loss or gain
- Changes in bladder or bowel movements
- Indigestion or discomfort after eating
- Diarrhoea, constipation and bloody stools
- A lump or thickening under the skin
- Yellowing, darkening or redness of the skin
- Sores that don't heal
- Moles that change appearance
- Persistent cough, difficulty swallowing or hoarseness
- Shortness of breath and chest pain
- Muscle or joint pain
Diagnosis of cancer
See a doctor if you notice any of the above symptoms. Your doctor may examine you for lumps, changes in skin colour or organ enlargement, and may also suggest:
- Laboratory tests: urine or blood tests may identify abnormalities.
- Imaging tests: these may include CT or MRI scans, bone scans, ultrasound or X-ray.
- Biopsy: your doctor will collect a tissue sample for laboratory testing.
If your doctor suspects cancer, you may be referred to specialists, such as:
- An oncologist, who specialises in cancer
- A radiation oncologist, who treats cancer with radiation
- A haematologist, who treats blood diseases
- A surgeon
Once cancer is diagnosed, it is important to determine its extent or stage (whether the cancer has spread to other parts of the body) before deciding on treatment options.
Treatments and drugs
These days there are several cancer treatments are available. Treatment will depend on the type and stage of the cancer, and the patient’s health and preferences.
Cancer treatments may aim to:
- Kill cancer cells (primary treatment). The goal is to remove the cancer.
- Kill remaining cancer cells (adjuvant therapy). The goal is to kill cancer cells that remain after primary treatment.
- Manage side effects (palliative care). The goal is to decrease pain or other symptoms, helping to maintain quality of life.
Possible treatments include:
- Surgery to remove the cancer, or as much as possible.
- Chemotherapy – using drugs to kill cancer cells.
- Radiation therapy – using high-powered energy beams, such as X-rays, to kill cancer cells.
- Stem cell transplant, also known as bone-marrow transplant.
- Biological therapy – using your body's immune system to fight cancer.
- Hormone therapy. Some types of cancer (e.g. breast cancer, prostate cancer) are fuelled by hormones. Removing or blocking hormones may stop or slow the cancer.
- Targeted drug therapy, which focuses on specific cell abnormalities.
- Clinical trials to investigate new ways of treating cancer.
- Alternative medicine. No alternative treatments have been proved to cure cancer, but some – such as acupuncture, hypnosis, massage, meditation, relaxation techniques and yoga – may help to relieve the side effects and stress of cancer and its treatment.
Can cancer be prevented?
There's no sure way to prevent cancer. But you can considerably reduce reduce your risk:
- Stop smoking. Smoking is linked to several types of cancer, not just lung cancer.
- Eat a healthy diet, including fruits, vegetables, whole grains and lean proteins.
- Exercise regularly.
- Maintain a healthy weight. Being overweight or obese increases your risk.
- Drink alcohol in moderation. Limit yourself to one (for women) or two (for men) drinks a day.
- Avoid sun exposure. Harmful ultraviolet rays can increase your risk of skin cancer. Stay in the shade, wear protective clothing and use sunscreen.
- Take screening tests. For some cancers, early diagnosis is crucial. For others, screening is recommended only for high-risk patients. Discuss your risk profile with your doctor.
- Immunise. Certain viruses increase your risk for cancer – for example, hepatitis B (liver cancer) and human papillomavirus or HPV (cervical cancer). Immunisation can prevent those viral infections.
Reference: Australian Institute of Health and Welfare & Australasian Association of Cancer Registries, ‘Cancer in Australia: an overview, 2012’.
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