Cancer — Benign and Malignant Tumours

Cancer is a non-communicable disease caused by uncontrolled cell division. In this lesson you will learn how normal cell division is regulated, what happens when it goes wrong, the difference between benign and malignant tumours, and the risk factors for cancer, as required by the AQA GCSE Combined Science Trilogy specification (8464).

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Normal Cell Division

Cells in the body divide by mitosis to produce new cells for:

• Growth — increasing the number of cells in a developing organism
• Repair — replacing damaged or worn-out cells
• Replacement — maintaining tissues (e.g. skin cells are constantly replaced)

Under normal circumstances, cell division is tightly controlled. Cells only divide when they receive the correct signals, and damaged or old cells are programmed to die (a process called apoptosis).

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What Is Cancer?

Cancer occurs when the normal control of cell division breaks down. Cells begin to divide uncontrollably, forming a mass of abnormal cells called a tumour.