Cancer
Laura Armstrong & Joe Wolfensohn
Teachers
Recall Questions
This topic requires prior knowledge of cell division by mitosis.
What is mitosis used for in the body?
Mitosis is used for growth and repair by producing genetically identical cells.
How many daughter cells are produced in mitosis?
2 genetically identical cells.
What controls the function of a cell?
The nucleus, as it contains the DNA which controls cell activity.
Topic Explainer Video
Check out this @JoeDoesBiology video that explains cancer, then read the study notes. Once you’ve gone through them, don’t forget to try the practice questions!
What Is Cancer?
Cancer is caused by uncontrolled cell division, due to changes (mutations) in the DNA of a cell.
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A tumour is a mass of abnormal cells dividing uncontrollably
Types of Tumours
|
Type |
Description |
|
Benign |
A growth of abnormal cells that is contained within one area (e.g. in a membrane). They do not spread to other parts of the body. |
|
Malignant |
These are cancerous tumours. They invade neighbouring tissues and spread to other parts of the body via the blood. They can form secondary tumours. When cells of a tumour spread via the bloodstream to other tissues, this is called metastasis. We say that malignant tumours can metastasise. |
Malignant tumours are more dangerous and difficult to treat than benign tumours because of the secondary tumours that have formed.
Causes of Cancer
Carcinogens are substances that are known to cause cancer e.g. tar or alcohol
Risk factors for developing cancer include:
Lifestyle (Environmental) Risk Factors:
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Smoking – strongly linked to lung cancer.
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Obesity – increases risk of many cancers, e.g. bowel cancer.
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UV exposure – increases risk of skin cancer.
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Alcohol – linked to mouth and liver cancers.
Genetic Risk Factors:
- Some cancers (e.g. breast and ovarian) can be inherited through faulty genes passed from parents to offspring.
How Is Cancer Treated?
The aim of cancer treatment is to remove or destroy cancerous cells while limiting damage to healthy tissue. Treatment type depends on:
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The type of cancer,
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The location and size of the tumour,
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Whether the cancer has spread.
1. Surgery
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Purpose: Physically removes the tumour from the body.
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When used: Often effective for benign tumours or when malignant tumours are localised.
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Limitations: Not useful if cancer has already spread to other parts of the body.
2. Radiotherapy
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Purpose: Uses targeted radiation to kill cancer cells.
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How it works: Damages the DNA of cancer cells so they can’t divide.
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Targeting: Usually focused on one area (e.g. a tumour site).
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Side effects: Can also damage healthy cells nearby, causing fatigue, skin irritation, or hair loss (depending on the site treated).
3. Chemotherapy
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Purpose: Uses anti-cancer drugs to kill rapidly dividing cells.
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How it works: The drugs circulate in the blood, so can target cancer cells throughout the body.
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Used for: Cancers that have spread or are not suitable for surgery.
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Side effects: Affects other fast-dividing cells (e.g. hair follicles, digestive lining), leading to hair loss, nausea, and immune suppression.
Key Terms
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Tumour – A mass of abnormal cells, dividing uncontrollably.
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Benign – Non-cancerous tumour that does not spread.
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Malignant – Cancerous tumour that spreads and forms secondary tumours.
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Exam Tip
Remember the key differences between benign and malignant tumours. Malignant tumours have cells that can spread to other parts of the body. Malignant tumours may form secondary tumours
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Practice Question
Explain why malignant tumours are dangerous. (3 marks)
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Malignant tumours are cancerous and can spread to other parts of the body through the blood.
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Malignant tumours invade surrounding tissues.
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They form secondary tumours which can disrupt the function of organs.
More Practice
Try to answer these practice questions from the TikTok videos on your own, then watch the videos to see how well you did!