What is Cancer? Understanding the disease
- Jane Butcher
- 5 days ago
- 3 min read
What Is Cancer? Understanding the Disease
Cancer is where some of the body’s cells begin to grow uncontrollably. Normally, cells grow, divide, and die in an organised way. This process allows the body to repair itself, replace old cells, and keep tissues healthy. Cancer develops when this normal system breaks down.
How Healthy Cells Normally Work
The human body is made up of trillions of cells. Each cell contains genes, which act like instructions telling the cell how to function. These instructions control when a cell should grow, divide, or stop growing.
Usually:
New cells are made when the body needs them
Damaged or old cells die and are replaced
Cells stay where they belong
This balance keeps the body working properly.
How Cancer Starts
Cancer begins when changes occur in a cell’s DNA. DNA is the genetic material inside cells that controls their behaviour. These changes are sometimes called mutations.
Mutations can happen because of:
Ageing
Smoking
Exposure to harmful chemicals
Radiation (including UV rays from the sun)
Infections caused by certain viruses
Inherited genetic changes
Random errors when cells divide
When enough changes build up, the cell may ignore the body’s normal controls and continue multiplying.
What Makes Cancer Dangerous?
Unlike normal cells, cancer cells can:
Grow when they shouldn’t
Ignore signals to stop dividing
Avoid dying when damaged
Invade nearby tissues
Spread to other parts of the body
When cancer spreads from its original site to another part of the body, this is called metastasis.
Tumours: Benign vs Malignant
Not all abnormal growths are cancer.
Benign tumours are non-cancerous. They usually grow slowly and do not spread.
Malignant tumours are cancerous. They can invade surrounding tissue and spread elsewhere.
Different Types of Cancer
There are over 100 different types of cancer. They are usually named after where they start in the body.
Common types include:
Breast cancer
Lung cancer
Prostate cancer
Bowel (colon) cancer
Skin cancer
Blood cancers such as leukaemia
Ovarian cancer
Each type behaves differently and may need different treatment.
Common Symptoms
Symptoms depend on where the cancer is and how advanced it is. Some common warning signs include:
Unexplained weight loss
Persistent tiredness
A lump or swelling
Changes in bowel or bladder habits
Ongoing pain
Unusual bleeding
Persistent cough
Changes in moles or skin
Many of these symptoms can be caused by conditions other than cancer, but persistent changes should be checked by a doctor.
How Cancer Is Treated
Treatment depends on the type, stage, and location of the cancer, plus the person’s overall health.
Common treatments include:
Surgery – removing the cancer
Chemotherapy – drugs that kill cancer cells
Radiotherapy – targeted radiation to destroy cancer cells
Immunotherapy – helping the immune system fight cancer
Targeted therapy – drugs aimed at specific cancer cell changes
Hormone therapy – used for some cancers such as breast or prostate cancer
Many people receive a combination of treatments.
Can Cancer Be Prevented?
Not all cancers can be prevented, but risk can be reduced by:
Not smoking
Maintaining a healthy weight
Exercising regularly
Eating a balanced diet
Limiting alcohol
Protecting skin from sun damage
Attending screening appointments
Getting recommended vaccines (such as HPV)
Final Thoughts
Cancer is caused by abnormal cell growth. While the word can feel frightening, advances in screening, early detection, and treatment mean many cancers are now highly treatable, and survival rates continue to improve. Understanding what cancer is helps people recognise symptoms, reduce risk, and seek help early.
I have personal experience of Cancer as well as being a Qualified Cancer and exercise Professional. I offer Personal Training to People with cancer as well as teaching a chair yoga class at Keech Living well. Find out more about my services here
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