What is cancer?
Cancer is not one disease but a large group of related conditions. In all of them, some of the body's cells begin to grow out of control. This is a general explanation; for anything about your own health, please see a doctor.
How it starts, in simple terms
The body is made of trillions of cells that normally grow, divide and die in an orderly way. Cancer begins when changes in a cell's instructions let it keep dividing when it should stop. Over time these cells can form a growth, and some can spread to other parts of the body.
Key terms you may hear
- Tumour: a lump or mass formed by extra cells. Not all tumours are cancer.
- Benign: a growth that does not spread to other parts of the body.
- Malignant: a growth that can invade nearby tissue and spread; this is what "cancerous" means.
- Metastasis: when cancer cells spread from where they started to other areas.
- Stage and grade: ways doctors describe how far a cancer has progressed and how the cells look.
Learn about screening, reducing risk, and signs to discuss with a doctor.
Common questions
Is every tumour cancer?
No. Many tumours are benign, meaning they do not spread. Only a healthcare professional can determine what a growth is, using appropriate tests.
Can cancer be cured?
Outcomes vary enormously by type, stage and individual circumstances. Many cancers are treatable, and some are curable, especially when found early. Your medical team is the right source for your situation.