How Does Cancer Kill You?


Cancer does not always cause death; in England and Wales, about 50% of those diagnosed with cancer live 10 years or more after diagnosis. As more treatments are developed, cancer survival has doubled in the last 40 years in the UK.1 

The stage of cancer determines the prognosis, with terminal (end-stage) cancer being one that cannot be cured or treated, and early-stage cancer having the best recovery rates. Any type of cancer has the potential to become terminal. Therefore, early detection of cancer is imperative as early stages are when treatment is most likely to be effective. 

More importantly, the manner in which cancer causes death is determined by the type of cancer and the parts of the body affected. Complications, a secondary disease, or a condition aggravating an already existing one with cancer is often what kills rather than cancer itself. Some common examples include organ failure, surgical complications, organ rupture, and infection.

What is Cancer?2

Humans are made up of trillions of cells that grow and divide as needed throughout life. When abnormal cells divide uncontrollably, cancer develops and starts to crowd out normal cells as they grow. These cancer cells can form tumours, which are lumps of tissue. This makes it difficult for your body to function properly. 

There are more than 200 different types of cancer. In some ways, these cancers are similar, but they differ in terms of how they grow, spread, and respond to treatment. Some cancers are quick to grow and spread; others develop at a slower pace. Some cancers have a higher proclivity for spreading to other parts of the body; others prefer to remain stationary. Some cancers respond best to surgery, while others respond better to drugs such as chemotherapy. To achieve the best results, two or more treatments are frequently used.

Stages of Cancer 

The size of a tumour and how far it has spread from its origin are described by the stage of cancer. If you have been diagnosed with cancer, you may be subjected to additional tests to determine the stage so that doctors can determine the best treatment options for you.3 

The stage of cancer is crucial in determining the best treatment option for a patient. A lower stage (stage 1 or 2) indicates that the cancer has not spread far. A higher number (stage 3 or 4) indicates that it has spread further. Stage 4 is the most advanced, also known as "secondary" or "metastatic" cancer.2  

How Different Cancers Kill 

The cause of death varies depending on the type of cancer. Some cancers begin in or spread to a part of the body that performs vital functions; when the normal function of some organs is affected, there is a much higher chance of death.

1. Digestive System Organs - Stomach, Esophagus, Pancreas, Liver, Bowel

When cancer or tumours grow large enough in the abdominal region, they can block the flow of food and waste through the digestive tract, preventing food from reaching the intestinal tract and preventing nutrients and calories from being absorbed.4 You may also have some symptoms of malnutrition, such as lack of appetite, inability to concentrate, constant feeling of being cold, and loss of weight.5 Alternatively, these tumours can grow through the bowel or stomach wall, causing a hole that allows the contents of the bowel or stomach to spill into the intestinal cavity, causing severe infection, which can lead to death. 

2. Lung 

Cancer may obstruct a portion of the lung, causing it to collapse and become infected. As a result, you may not have enough healthy lung tissue to absorb the oxygen you need, leading to organ failure in the worst case.

3. Bones

Malignant hypercalcemia is one of the most common disorders in patients with advanced-stage cancer, affecting up to 44% of patients.6 Cancer in the bones causes calcium to be released into the bloodstream, creating a calcium imbalance throughout the body. Too much calcium in the blood can interfere with heart, kidney, and muscle function, potentially causing organ failure, comas and eventually death.

In some cases, cancer cells can spread to the bone marrow, resulting in an inability to produce new red blood cells for oxygen supply, white blood cells for immunisation, and platelets to stop bleeding. Thus, you may die for a variety of reasons related to oxygen starvation, weak immune system or haemorrhaging. 

4. Liver

The liver is the chemical factory of the body. It performs a variety of functions and is critical in maintaining the chemical balance of the body. Liver cancer causes a chemical imbalance that leads to an inability to detoxify the blood. If this chemical balance cannot be restored, it can be fatal.

5. Blood

Cancers can invade and damage blood vessels that are in the most vital organs of the body, resulting in bleeding or reduced oxygen flow. Complications called pulmonary embolism (PE) may occur and cause between 100,000 and 180,000 deaths per year in the United States.7

6. Brain 

When the brain runs out of space inside the skull, it tries to find a way to make more space by finding folds or openings with the available space. This potentially deadly side effect is called brain herniation. It may occur both with cancer that originates in the brain and cancer that has spread to the brain. Common symptoms include severe headaches, high blood pressure, irregular pulses, heart attack, coma, and loss of reflexes.


Even if your cancer is not curable, many treatments can keep it under control for a long time. However, as cancer spreads to different parts of the body, symptoms become more severe, as does the risk of death. Early detection of cancer makes it easier to treat it before it spreads and causes complications. Therefore, it is critical to have regular cancer screenings, perform regular self-exams and speak with your doctor about any concerns. In addition to this, you can also change your lifestyle to reduce risk factors for certain cancers.8 Risk factors include:

  • Alcohol

Alcohol consumption increases your chances of developing cancers of the mouth, throat, oesophagus, larynx (voice box), liver, and breast. The more you drink, the higher your risk. Overindulgence of alcohol is also linked to an increased risk of developing type 2 diabetes, as it is high in calories and can cause weight gain. According to current government recommendations, you should not drink more than 14 units or six glasses of wine per week, and those units should be spread over three to four days.

  • Obesity

Obese people are more likely to develop cancers of the breast (after menopause), colon, rectum, endometrium, oesophagus, kidney, pancreas, and gallbladder, as fat can accumulate around them. Conversely, eating a healthy diet, starting exercise, and maintaining an average weight, may help reduce the risk of certain cancers and other diseases, such as heart disease, type 2 diabetes, and hypertension. Thus, try to keep your overall weight and body mass index (BMI) within the normal ranges of 18.5-24.9.9

  • Sunlight

UV (ultraviolet), radiation emitted by the sun, sunlamps, and tanning booths, can cause premature skin ageing and damage, leading to skin cancer. Thus, people should limit their time in the sun, particularly between mid-morning and late afternoon. Try to wear a hat, sunglasses, long sleeves, and sunscreen to protect yourself from direct sunlight.

  • Tobacco

Tobacco use is one of the leading causes of cancer and cancer-related deaths. As tobacco products contain many chemicals that damage DNA, people who use or are regularly exposed to tobacco smoke are at higher risk of cancer. It causes almost nine out of every 10 cases of lung cancer, and can also develop other types of cancer; including cancer of the larynx, mouth, oesophagus, throat, bladder, kidney, liver, stomach, pancreas, colon and rectum, and cervix.9 Therefore, smokers who do not have cancer or have just been diagnosed are strongly encouraged to quit smoking, as smoking cessation at the time of cancer diagnosis also reduces the risk of death. If you have difficulty quitting smoking, the NHS also provides a 'stop smoking service' at a local pharmacy or GP surgery.


What does cancer do to the body?

The uncontrolled growth of abnormal cells causes the standard control mechanism of the body to fail. These extra cells may form a tumour which is a mass of tissue. They can also grow into nearby organs, blood vessels, and nerves or begin to push on them. This pressure causes some of the signs and symptoms of cancer.

How likely are you to die from cancer?

The mortality rate for different types of cancer varies significantly. According to cancer death statistics from 2013 to 2017, the overall cancer death rate is 158.3 per 100,000 people per year. People assigned male at birth (AMAB) have a higher mortality rate from cancer in comparison to people assigned female at birth (AFAB) (189.5 per 100,000 people AMABand 135.7 per 100,000 people AFAB).8

What is the most common cause of death in cancer patients?

Infection is the leading cause of death in cancer patients (36%) and a contributing factor in other 68% of the cases. The second leading cause of death is hemorrhagic and thromboembolic phenomena (18%), which are also contributing factors in another 43% of deaths.10

Is death from cancer painful?

Unfortunately, most people diagnosed with cancer experience pain at some point, and about half of those who die from cancer do so in pain.11 However, the palliative care (end of life) and pain management teams in the hospital are there to help manage pain.

What is the fastest killing cancer?

Given the difficulty in diagnosing and treating pancreatic cancer early on, there must be a sense of urgency in treating those affected by the disease; therefore, it is determined as the fastest killing cancer.12

What is the worst cancer?

According to published data from the Nuffield Trust, cancers with the lowest estimated 5-year survival rates are mesothelioma (7.2%), pancreatic cancer (7.3%), and brain cancer (12.8%) in the UK.13

People Also Ask:

  • Why Do People with Cancer Receive Radiation Therapy?
  • How Radiation Is Used with Other Cancer Treatments?
  • How Radiation Therapy Works Against Cancer?
  • How Much Radiation Therapy Costs?
  • What is a tumour?
  • How Does Cancer Cause Life Threatening Complications?
  • What is the cancer stage?
  • How can cancer kill you?
  • Cancer: How does it kill?
  • How Does Cancer Actually Kill You?


  1. Cancer Research UK,
  2. American Cancer Society, 
  3. NHS UK, 
  4. Riihimäki M, Thomsen H, Sundquist K, Hemminki K. Colorectal cancer patients: what do they die of?. Frontline Gastroenterology [Internet]. 2012 [cited 11 October 2021];3(3):143-149. Available from: 
  6. Mirrakhimov A. Hypercalcemia of malignancy: An update on pathogenesis and management. North American Journal of Medical Sciences [Internet]. 2015 [cited 11 October 2021];7(11):483. Available from: 
  8. National Cancer Institute, 
  9. CDC, 
  10. Ambrus JL, Ambrus CM, Mink IB, Pickren JW. Causes of death in cancer patients. Journal of Medicine [Internet]. 1975 [cited 11 October 2021];6(1):61-64. Available from:
  11. Platt M. Pain Challenges at the End of Life—Pain and Palliative Care Collaboration. Reviews in Pain [Internet]. 2010 [cited 11 October 2021];4(2):18-23. Available from: 
  12. Pancreatic Cancer UK,  
  13. Nuffield Trust, 
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Yuting Jiang

Master of Science in Pharmacy - UCL (University College London)
Dynamic Master of Pharmacy student driven by a passion for providing high-quality patient care. Engaged in rigorous programmes of professional development, refining a myriad of skills, including data, analytical, and numerical. Gained excellent multi-lingual communication skills used to great effect in developing strong, multidisciplinary relationships and in the confident presentation of research findings both verbally and in writing.

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