Cancer Basics
Hate the disease, but not the diseased
Cancer starts in our cells — the tiny building blocks that make up the organs and tissues of our body. Usually, these cells divide to make new cells in a controlled way. This is how our bodies grow, heal and repair.
Sometimes this process goes wrong and a cell becomes abnormal. The abnormal cell keeps dividing and making more abnormal cells. These cells can form a lump, which is called a tumour.
Benign vs malignant
Benign (not cancer)
A lump that is not cancerous cannot spread to anywhere else in the body.
Malignant (cancer)
A cancerous lump can grow into surrounding tissue and may spread to other organs.
How cancer spreads
Cancer cells sometimes break away from the primary cancer and travel through the blood or lymphatic system to other parts of the body. Cancer that develops somewhere else is called a secondary cancer (metastasis).
Cancer and cell types
The type of cancer is generally based on the part of the body and the type of cell where the cancer first developed. Common sites include the oral cavity, lungs, breasts, prostate, cervix, colon and oesophagus.
- Carcinomas — start in epithelial cells (about 80–90% of cancers)
- Leukaemias & lymphomas — blood and lymphatic system (about 7%)
- Sarcomas — connective tissue cells (about 1%)
Why the type matters
Different cancers behave differently and respond to different treatments. Doctors classify cancer by site (where it first started) and cell type (what kind of cell it came from).