• Question: Why does cancer kill us?

    Asked by benmiller to Shonna, Ryan, Ross, Marianne, Anabel on 7 Jun 2019.
    • Photo: Marianne King

      Marianne King answered on 7 Jun 2019:


      I’m not an expert on cancer, but some of the reasons it kills are that tumours can sometimes grow and press against organs, blood vessels or nerves. This can impair vital organ function or prevent blood going where it needs to. Cancer can also have a very negative effect on the immune system, leading to infections which can sadly be too much to overcome.

    • Photo: Anabel Martinez Lyons

      Anabel Martinez Lyons answered on 10 Jun 2019:


      Hi Ben – a very good question with a multi-part answer, and I’ll do my best to make it short. Cancer is defined as uncontrolled cell growth, resulting in tumours which can form in any organ (some forms of “primary” cancer (originating in a certain organ) are more common than others, such as breast or skin cancers). Tumours themselves can be problematic as they can block major blood vessels or have negative effects on that organ’s function in the body, but typically when they cause the most trouble is when they break away and travel in the blood or lymph systems to other parts of the body – this process is known as metastasis. It’s often this spread (and the negative impact on one or more major organs) that kills someone. So a few ways this happens: 1) malnourishment & dehydration- tumours (either primary or metastatic ones) affecting organs like the stomach, pancreas or intestine can inhibit the body from digesting nutrients from food properly, leading to fatigue, impaired immune systems and trouble healing and repairing tissues in the body. This can also affect the body’s ability to retain and use water, leading to dehydration – if this happens for long enough, both can be fatal, 2) respiratory failure – tumours affecting the lungs can result in trouble breathing/exchanging important gases, leading to oxygen starvation in important tissues and fatigue, 3) brain impairment – tumours in the brain can kill off healthy brain cells leading to a whole host of nasty symptoms, from seizures to loss of essential functions like breathing, seeing, talking, memory or movement, 4) effects on our bone marrow – bone marrow is crucial for making healthy red and white blood cells (important for carrying oxygen and defending the body against infection, respectively) and platelets (blood clotting factors), together these three cell types are important for attacking infections, healing injuries and carrying oxygen around the body. Cancers of the bone marrow can deplete these cell types and make the body weak and prone to infections, excessive bleeding and anaemia, 5) liver failure – the liver filters your blood for anything potentially harmful. Liver tumours can stop this process from functioning normally and cause a build up of harmful things in the blood which can damage many tissue types. 6) Calcium level changes – a rarer, but serious, implication of tumours in the bone marrow is a rise in blood level calcium (known as hypercalcaemia). Increased calcium levels can be deadly if not managed – this is because many organs, especially the heart and brain, require proteins that are tightly regulated by calcium. So if the calcium levels change, so do these proteins’ ability to function normally. All in all – cancer is a complex and pretty serious condition, and each case is treated individually based on the patient’s exact disease progression. The more scientists understand the causes and effects of the many types of cancers, the better chance we have of preventing deaths from cancer in future.

    • Photo: Shonna Johnston

      Shonna Johnston answered on 11 Jun 2019:


      In my job I work with scientists who research the tumour microenvironment.
      This is the area where the cancer cells settle and take hold. What they are interested in is how the surrounding cells interact with the tumour cells and vice versa. They investigate what signals are involved such as chemicals released by the cells and whether these have positive or negative effects on the tumour cells. Finding out how this happens could form the basis for treatment. Stopping the tumour from increasing in size should stop the bad effects on the body and prevent death.

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