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What is Cancer?

Cancer is a leading cause of death worldwide, accounting for nearly 10 million deaths in 2020, or nearly 1 in 6 deaths. In 2020 in England, 137,234 people died from cancer, and the number of deaths has increased by 8% since 2001. But after accounting for the fact that England’s population is both growing and ageing, the rate of cancer deaths has actually fallen.

On average, someone is diagnosed with cancer every 90 seconds in the UK, which is around 391,000 people each year. NHS statistics show that there were more cancers diagnosed in males (169,599) than in females (157,575) in 2019.

According to Macmillan Cancer Support there are almost 3 million people living with cancer in the UK. They predict this number will rise to nearly 3.5 million by 2025, and 4 million by 2030.

When coronavirus first emerged, the NHS saw cancer patient numbers drop dramatically as people stayed away because of fear of the virus, or because they didn’t want to burden the NHS, despite experiencing cancer symptoms. However, as COVID infections have fallen and continue to decrease across the UK, record numbers of people are coming forward for cancer tests, with almost a quarter of a million referrals in one month, according to the latest data from the NHS.

The figures show that 246,000 people were checked for cancer in November 2021, the highest month on record – three times as many compared to the beginning of the COVID pandemic in April 2020, when people were reluctant to come forward.

Suffering with cancer

What is cancer?

Cancer can start almost anywhere in the human body; it is a disease in which some of the body’s cells grow uncontrollably and spread to other parts of the body.

The human body is made up of trillions of cells. Normally, human cells grow and multiply through a process called cell division, to form new cells as the body needs them. When cells grow old or become damaged, they die, and new cells take their place.

Sometimes this orderly process breaks down, and abnormal or damaged cells grow and multiply when they shouldn’t. These cells may form tumours, which are lumps of tissue. Tumours can be cancerous or non-cancerous (benign).

Cancerous tumours spread into, or invade, nearby tissues and can travel to distant places in the body to form new tumours, a process called metastasis. Cancerous tumours may also be called malignant tumours. Many cancers form solid tumours, but cancers of the blood, such as leukaemia, generally do not.

Benign tumours do not spread into, or invade, nearby tissues. When removed, benign tumours usually don’t grow back, whereas cancerous tumours sometimes do. However, benign tumours can sometimes be quite large, and some can cause serious symptoms or be life-threatening, such as benign tumours in the brain.

Cancer is a genetic disease, that is, it is caused by changes to genes that control the way our cells function, especially how they grow and divide.

Genetic changes that can cause cancer happen because of:

  • Errors that occur as cells divide.
  • Damage to DNA caused by harmful substances in the environment, such as the chemicals in tobacco smoke and ultraviolet rays from the sun.
  • Genetic inheritance from our parents.

The body normally eliminates cells with damaged DNA before they turn cancerous. But the body’s ability to do so goes down as we age. This is part of the reason why there is a higher risk of cancer later in life.

The genetic changes that contribute to cancer tend to affect three main types of genes—proto-oncogenes, tumour suppressor genes, and DNA repair genes. These changes are sometimes called “drivers” of cancer.

A cancer that has spread from the place where it first formed to another place in the body is called metastatic cancer. The process by which cancer cells spread to other parts of the body is called metastasis. Metastatic cancer has the same name and the same type of cancer cells as the original, or primary, cancer. For example, breast cancer that forms a metastatic tumour in the lung is metastatic breast cancer, not lung cancer.

What are the types of cancer?

Macmillan Cancer Support lists 127 cancer types. However, in the UK over half of cancers fall into four main types: prostate, breast, lung, and bowel/colorectal.

Prostate cancer is the most common cancer in the UK. Around 52,300 men are diagnosed with prostate cancer in the UK each year, that is about 1 in 8 men who will get prostate cancer. It is not always life-threatening, but when it is, the earlier you catch it the more likely it is to be cured.

There are around 56,000 new cases of breast cancer every year in the UK, which is over 150 cases every day. In women, on average there were 55,545 new cases each year and in men, there were 375 new breast cancer cases, according to 2016-2018 data.

There are around 48,500 new lung cancer cases in the UK every year, which is more than 130 every day. Lung cancer is the third most common cancer in the UK. It is the second most common cancer in females in the UK, with around 23,300 new cases every year, and in males, with around 25,300 new cases every year, according to 2016-2018 data.

Bowel cancer is the fourth most common cancer in the UK and the second biggest cancer killer. Nearly 43,000 people are diagnosed with bowel cancer every year in the UK and around 268,000 people living in the UK today have been diagnosed with bowel cancer.

NHS Digital published Cancer Registration Statistics in 2019, a list of the UK’s most common cancer types by gender:


  • Prostate cancer 28%. In the UK about 52,000 men are diagnosed with prostate cancer each year. Although it is more common over the age of 65, it can happen at a younger age but is uncommon under 50. Trans women or non-binary assigned males at birth need to be aware of prostate cancer.
  • Lung cancer 12%.
  • Bowel / Colorectal cancer 12%.
  • Skin / Melanoma 5%.
  • Non-Hodgkin Lymphoma 4%.
  • Bladder cancer 4%.
  • Kidney cancer 4%.
  • Lip / Oral / Pharynx cancer 3%.
  • Oesophagus cancer 3%.
  • Leukaemia 3%.
  • Pancreatic cancer 3%.
  • Liver 2%.


  • Breast cancer 30%. Each year, about 55,000 women are diagnosed with breast cancer in the UK. It is more common in women who are aged 50 and over. Breast cancer in men is rare. About 375 men in the UK are diagnosed with breast cancer each year.
  • Lung cancer 12%.
  • Bowel / Colorectal cancer 11%.
  • Uterus (womb) cancer 5%.
  • Skin / Melanoma 5%.
  • Ovarian cancer 4%.
  • Non-Hodgkin Lymphoma 3%.
  • Pancreatic cancer 3%.
  • Kidney cancer 2%.
  • Leukaemia 2%.
  • Lip / Oral / Pharynx cancer 2%.
  • Cervix cancer 2%.

Carcinomas are the most common type of cancer. They are formed by epithelial cells, which are the cells that cover the inside and outside surfaces of the body.

Sarcomas are cancers that form in bone and soft tissues, including muscle, fat, blood vessels, lymph vessels, and fibrous tissue such as tendons and ligaments.

Cancers that begin in the blood-forming tissue of the bone marrow are called leukaemia. These cancers do not form solid tumours; instead, large numbers of abnormal white blood cells build up in the blood and bone marrow, crowding out normal blood cells. The low level of normal blood cells can make it harder for the body to get oxygen to its tissues, control bleeding, or fight infections.

Lymphoma is a cancer that begins in lymphocytes T cells or B cells. These are disease-fighting white blood cells that are part of the immune system. In lymphoma, abnormal lymphocytes build up in lymph nodes and lymph vessels, as well as in other organs of the body.

Multiple myeloma is cancer that begins in plasma cells, another type of immune cell. The abnormal plasma cells, called myeloma cells, build up in the bone marrow and form tumours in bones all through the body. Multiple myeloma is also called plasma cell myeloma and Kahler disease.

Melanoma is a cancer that begins in cells that become melanocytes, which are specialised cells that make melanin, a pigment that gives skin its colour. Most melanomas form on the skin, but melanomas can also form in other pigmented tissues, such as the eye.

Man diagnosed with prostate cancer

What are the signs and symptoms of cancer?

Signs and symptoms are more often caused by something less serious than cancer, but if it is cancer, spotting it early can make a real difference. Common symptoms of cancer include diarrhoea that lasts for three weeks or more, new lumps or bumps and unexplained weight loss or fatigue.

Cancer can affect people in different ways. The type of symptoms a person may have can be different to others, and some people don’t have any symptoms.

There are over 200 different types of cancer that can cause many different signs and symptoms, so it is important to be aware of what is normal for you and to speak to your doctor if you notice any unusual changes or something that won’t go away.

Some key signs and symptoms that you can be aware of include but are not limited to:

  • Very heavy night sweats or fever – Sweating at night or having a high temperature or fever can be caused by infections or a side effect of certain medications. It is also often experienced by women around the time of the menopause. But speak to your doctor if you have very heavy, drenching night sweats, or an unexplained fever.
  • Fatigue – There are lots of reasons why you may feel more tired than usual, particularly if you are going through a stressful event, or having trouble sleeping. But if you are feeling tired all the time, or for no clear reason, it could be a sign that something is wrong, so speak to your doctor.
  • Unexplained bleeding or bruising – Unexplained bleeding or bruising when you have not hurt yourself is important to get checked out by your doctor. This includes blood in your poo or pee, as well as vomiting or coughing up blood. It also includes any unexplained vaginal bleeding between periods, after sex or after the menopause. No matter how much blood or what colour it is – the blood can be red, or a darker colour like brown or black – speak to your doctor.
  • Unexplained pain or ache – Pain is one way our body tells us that something is wrong. As we get older, it is more common to experience aches and pains. But unexplained or persistent pain anywhere in the body could be a sign of something more serious.
  • Unexplained weight loss – Small weight changes over time are quite normal, but if you have lost a noticeable amount of weight without trying to, tell your doctor.
  • Unusual lump or swelling anywhere – Persistent lumps or swelling in any part of your body should be taken seriously. This includes any lumps in the neck, armpit, stomach, groin, chest, breast or testicle.
  • Sore that does not heal – The skin repairs itself very quickly and any damage usually heals within a week or so. When a spot, wart or sore doesn’t heal, even if it is painless, a doctor needs to check it.
  • New mole or changes to a mole – Most moles are harmless. But be aware of any new moles or existing moles that change in size, shape or colour, become crusty, itch, hurt, bleed or ooze.
  • Breathlessness – It is not unusual to feel out of breath every now and then. But if you notice that you are feeling breathless more than usual or for a lot of the time, tell your doctor.
  • Persistent cough – Coughs are common with colds and some other health conditions. But if a cough doesn’t go away in a few weeks or gets worse, it could be a sign of cancer.
  • Mouth or tongue ulcer or patch that won’t heal – It is common to get ulcers that are small sores in the mouth when you are a bit run down. They usually get better in about two weeks, but you should report an ulcer or red or white patch that doesn’t heal after three weeks to your doctor or dentist.
  • Persistent heartburn or indigestion – It is normal to feel slight discomfort or pain sometimes after eating a large, fatty or spicy meal. But if you have heartburn – acid reflux – or indigestion a lot, or if it is particularly painful, then you should see your doctor.
  • Persistent bloating – It is quite common to experience a bloated or swollen tummy that comes and goes from time to time. But if you feel bloated most days, even if it comes and goes, talk to your doctor.
  • Bowel changes – Let your doctor know if you have noticed a change in your bowel habits. A change in bowel habits can include constipation, looser poo or pooing more often.
  • Problems peeing – These might include needing to go more often or urgently, experiencing pain when peeing, or not being able to go when you need to.

It is important not to put any unusual changes, aches or pains down to “just getting older” or assume a symptom is because of a health condition you already know about. Whatever your age, it is always best to listen to your body and talk to your doctor if something is not normal for you.

What causes cancer?

Doctors do not know the exact causes of cancer. Many of the risk factors listed below may have a causal effect in some people. Cancer arises from the transformation of normal cells into tumour cells.

These changes are the result of the interaction between a person’s genetic factors and three categories of external agents, including:

  • Physical carcinogens, such as ultraviolet and ionizing radiation.
  • Chemical carcinogens, such as asbestos, components of tobacco smoke, alcohol, aflatoxin (a food contaminant), and arsenic (a drinking water contaminant).
  • Biological carcinogens, such as infections from certain viruses, bacteria or parasites.

The World Health Organization (WHO), through its cancer research agency, the International Agency for Research on Cancer (IARC), maintains a classification of cancer-causing agents.

What are the risk factors of cancer?

Everyone has a certain risk of developing cancer, but there are risk factors that can increase your chance of developing it. A combination of genes, lifestyle and environment can affect this risk. Having one or more risk factors does not mean you will get cancer. Also, having no risk factors does not mean you will not develop cancer.

A person’s risk of cancer depends on many different things. People often worry that a history of cancer in their family greatly increases their risk of developing it. But fewer than 1 in 10 cancers are associated with a strong family history of cancer. If you are worried, you should talk to your GP.

For most people, increasing age is the biggest risk factor for developing cancer. In general, people over 65 have the greatest risk of developing cancer. People under 50 have a much lower risk. The UK population is growing and ageing, and as age is a risk factor, more people will be affected by cancer in their lifetime.

Lifestyle risk factors include:

  • Being overweight – This increases the risk of many types of cancer, including cancers of the bowel, kidney, womb and oesophagus. Women who are overweight and have been through the  menopause also have a higher risk of breast cancer.
  • Smoking – In the UK, more than 1 in 4 cancer deaths – over 25% – are caused by smoking. Breathing in other people’s smoke, known as passive smoking, also increases the risk of developing cancer. Not smoking is the best thing you can do to reduce your risk of cancer. Harmful chemicals in cigarette smoke affect the entire body, not just the lungs.
  • Drinking alcohol – This increases your risk of mouth and throat cancers. But it is also linked to other cancers. In general, the more you drink, the higher your risk. Your risk is even higher if you also smoke.
  • Ultraviolet (UV) radiation – Spending some time outside in the sun helps us to stay healthy, as our bodies need sunlight to make vitamin D. However, it is important to protect the skin from burning, as this can increase the risk of skin cancers. Using sun beds or sun lamps also increases the risk of skin cancer.

Environmental risk factors include:

Exposure to harmful substances in the environment or workplace can cause cancer. Substances that produce cancer are called carcinogens.

Some of these carcinogens can cause cancer years after you have been exposed to them, and they can include:

  • Asbestos – This is a natural mineral that is now banned in the UK. It can damage the lungs and cause mesothelioma. The people most likely to have been exposed to asbestos at work include people who work in construction and ship and boiler makers. People who have not worked with asbestos may also be at risk. This can happen if they have been exposed to asbestos factories, buildings that contain asbestos or if they live with someone working with asbestos.
  • Some chemicals have been linked to bladder cancer. The chemicals were previously used in dye factories and other industries. Many of these chemicals are now banned. But bladder cancer can take more than 25 years to develop after you have been exposed to the chemicals. Some chemicals can also slightly increase the risk of skin cancer. Many of these chemicals are also banned.
  • One of the main environmental causes of cancer is ultraviolet (UV) radiation from the sun. We know that many skin cancers, including melanoma, are caused by spending too much time in the sun. The people most at risk are those who work outside and those who are fair-skinned.
  • Radon – This is another possible source of radiation that may be linked to cancer. Radon is a natural gas that is found in rock in parts of the UK. Radon has been linked to lung cancer. But the risk is very small.
  • Poverty and deprivation – Male and female diagnosis rates in the 20% most deprived areas of England are at least 16% higher than for those in the 20% least deprived areas.
  • Viral infections – These are very common and usually do not cause cancer to develop. A small number of viruses have been linked to a higher risk of certain types of cancer.
    These include:
    – Human papillomaviruses (HPV).
    – Epstein-Barr virus.
    – Hepatitis B and C.
    – HIV.
    – T-cell leukaemia virus.
  • Low immunity – If you have low immunity, your immune system does not work as well. This means you are more likely to get infections.
    People with a lower immunity may have:
    – Had a transplant and take drugs to suppress the immune system –These drugs stop the body from rejecting the transplant.
    – HIV (human immunodeficiency virus).
    – A medical condition that lowers their immunity.
    If you have low immunity, you may be more likely to develop some cancers.
    These cancers include:
    – Lymphoma.
    – Non-melanoma skin cancer.
    – Kaposi’s sarcoma.
    – Cancers caused by a virus or bacteria.

Can cancer be prevented?

Not all cancers can be prevented but there are things that you can do to reduce your risk. These include not smoking and keeping a healthy weight. Around 1 in 3 cases of the most common cancers – about 33% – could be prevented by eating a healthy diet, keeping to a healthy weight and being more active. There are some things you can do to lower your risk of developing cancer but you cannot reduce your risk completely through your lifestyle.

There is no single food that causes or prevents cancer. Eating a balanced diet is good for your overall health and helps reduce your risk of some cancers. It can also help you to keep to a healthy weight.

Many studies have found that regular physical activity can reduce the risk of cancer. You should try to do at least 30 minutes of activity every day. Cancer risk is reduced further if you are active for more than 30 minutes a day and if you exercise harder (vigorous activity).

HPV is the name given to a very common group of viruses. There are many types of HPV, some of which are called high risk because they are linked to the development of cancers, such as cervical cancer, anal cancer, genital cancers, and cancers of the head and neck.

The HPV vaccine is offered for free to children aged 11–13, and some other groups. It helps protect against HPV infection, reducing the risk of some types of cancer. The vaccine has been proven to be safe and effective.

What are the stages of cancer?

Cancer arises from the transformation of normal cells into tumour cells in a multi-stage process that generally progresses from a pre-cancerous lesion to a malignant tumour. There are different staging systems for different types of cancer.

One commonly used staging system is the TNM system.

TNM stands for tumour, node and metastases:

  • T describes the size of the tumour. This is usually a number between 1 and 4. 1 is a small cancer; 4 is a larger or more advanced cancer.
  • N describes whether the cancer has spread to the lymph nodes. The number can be between 0 and 3. 0 means there are no cancer cells in the lymph nodes; 3 means more lymph nodes are affected by cancer.
  • M describes whether the cancer has spread to another part of the body, known as metastatic or secondary cancer. The number is either 0 or 1. 0 means the cancer has not spread to other parts of the body; 1 means it has spread.

Another commonly used staging system is the number system. There are usually 3 or 4 number stages for each cancer type. Stage 1 describes an early cancer that has not spread anywhere else in the body. Stage 4 describes a cancer that has spread to other parts of the body.

Each cancer has its own staging system. Staging can be very complicated. Your doctor can tell you more about the stage of your cancer. Not every cancer uses the TNM or number system. Some have very specific systems only used for that type of cancer.

Grading is about how the cancer cells look under the microscope compared with normal cells.

Many cancers use the following grading system:

  • Grade 1 – Low-grade or well differentiated, the cancer cells look similar to normal cells and usually grow more slowly.
  • Grade 2 – Moderate or intermediate-grade, the cancer cells look more abnormal and are slightly faster growing.
  • Grade 3 – High-grade or poorly differentiated, the cancer cells look very different from normal cells and may grow more quickly.

There are different grading systems for some cancers. Some have a grade 4. Some have a system only used for that specific cancer. Your doctor can tell you more about the grade of your cancer.

Can cancer be detected early?

Cancer mortality is reduced when cases are detected and treated early. There are two components of early detection: early diagnosis and screening.

Early diagnosis focuses on detecting symptomatic patients as early as possible, while screening consists of testing healthy individuals to identify those having cancers before any symptoms appear.

There are three national cancer screening programmes in England:

  • Cervical screening.
  • Breast screening.
  • Bowel screening.

Significant improvements can be made in the lives of cancer patients by detecting cancer early and avoiding delays in care; for example, if bowel cancer is diagnosed early, more than 90% of bowel cancer cases can be treated successfully. If breast cancer is detected early, treatment is more successful and there is a good chance of recovery.

How is cancer diagnosed?

If you go to your doctor with symptoms, they will examine you and may arrange some tests. If your doctor thinks your symptoms could be caused by cancer, they will refer you to a specialist. This will be a medical professional who specialises in diagnosing and treating the type of cancer your own doctor thinks could be causing the symptoms you have.

Tests for cancer may vary according to the type of cancer.

These may include:

  • Blood tests.
  • Biopsy.
  • Scans.
  • X-rays.

The type of tests that you may need depends on the symptoms you have and the part of the body affected. Healthcare staff will explain what will happen at each test and they may also give you written information about the tests.

You will usually be given an appointment to go back and see your specialist, so that they can explain the results of your tests. They should use clear language and give you enough time to ask questions.

Getting an accurate diagnosis of cancer can take weeks or sometimes months. Usually, this will not impact on how successful the treatment will be. If you are diagnosed with cancer, you should not have to wait more than 31 days from the diagnosis and a decision to start treatment before you have treatment.

How is cancer treated?

Surgery is the first treatment to try for most types of cancer, as solid tumours can usually be surgically removed.

Two other commonly used treatment methods are:


Powerful cancer-killing medicines used to kill cancer cells. There are many different types of chemotherapy medicine, but they all work in a similar way. They stop cancer cells reproducing, which prevents them from growing and spreading in the body. Chemotherapy may be used if cancer has spread or there is a risk that it will.

Chemotherapy can be given in several ways.

The most common types are:

  • Intravenous chemotherapy – This is chemotherapy given into a vein, and is usually done in hospital and involves medicine being given through a tube in a vein in your hand, arm or chest.
  • Oral chemotherapy – This is chemotherapy tablets and usually involves taking a course of medicine at home, with regular check-ups in hospital.


The controlled use of high-energy X-rays. This is a treatment where radiation is used to kill cancer cells. Radiotherapy may be used in the early stages of cancer or after it has started to spread. It is generally considered the most effective cancer treatment after surgery, but how well it works varies from person to person.

Radiotherapy can be given in several ways and is usually given in hospital.

The most common types are:

  • External radiotherapy – Where a machine is used to carefully aim beams of radiation at the cancer.
  • Brachytherapy – These are radiotherapy implants where small pieces of radioactive metal are, usually temporarily, placed inside your body near the cancer.
  • Radioisotope therapy – These are radiotherapy injections, capsules or drinks, where you swallow a radioactive liquid, or have it injected into your blood.
  • Intrabeam radiotherapy – Where radiation is delivered directly at the tumour during breast cancer surgery. this treatment is not available at all NHS hospitals.

For some people, the end of treatment means they are not likely to need any more cancer treatment. For other people, treatment is about managing the cancer over a long period of time.

Chemotherapy treatment

Final thoughts

Spotting cancer early increases the chances of survival. Anyone concerned about symptoms that they feel may be indicating cancer should in the first instance visit their own GP.

For anyone supporting someone with cancer, there are a number of advice and support organisations, including but not limited to:

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About the author

Evie Lee

Evie Lee

Evie has worked at CPD Online College since August 2021. She is currently doing an apprenticeship in Level 3 Business Administration. Evie's main roles are to upload blog articles and courses to the website. Outside of work, Evie loves horse riding and spending time with her family.

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