• Question: whats the main reason of cancer

    Asked by happyfeet to Enda, Jean, Kate, Kev, Tim on 17 Nov 2012.
    • Photo: Tim Downing

      Tim Downing answered on 17 Nov 2012:

      Hi Happyfeet,

      Cancer is a broad set of many diseases in which the body’s cell grow in an unregulated manner. Normally cell growth is determined by the body and the cells all communicate with one another so that they grow with a defined plan. For example, this is how your body knows to make four and not just three fingers on each hand, and then to make your thumb a bit shorter – imagine if you had a really long thumb!

      So cell grow is highly regulated and so when cells ignore these instructions, cancer may develop. The origin for ignoring the growth plan is in mutations in our DNA. We all get mutations in our cells, this is a natural occurrence. Normally, proteins in our cells detect this and the mutations are repaired. If the mutations are very bad, then the cell has a second plan – it will kill itself because it knows it is malfunctioning. Again, this natural process is designed to prevent cells living too long. For example, during foetal development in the womb, the fingers on hands are webbed like ducks’ feet before becoming separate into individual fingers. The foetus (baby before it is born) does this by telling all the cells in the webbed part between the fingers to die. It would be tricky to type if it didn’t!

      So we have two major factors: malfunctions in DNA repair, and then a problem with the natural cell death pathway (“apoptosis”). This doesn’t means these cells will become cancerous, but it means that they are unregulated by the body. Because the other normal cells may not realise this, the unregulated cells could then be allowed to divide and grow in an uncontrolled manner, leading to cancer.


    • Photo: Jean Bourke

      Jean Bourke answered on 20 Nov 2012:

      The main cause of cancer is cell division. Cancer occurs when cells divide and grow at an uncontrolled rate and invade other tissues. They can damage the surrounding area and hog the body’s resources essentially starving the patient.

      As Tim said when mistakes happen in copying DNA these can cause the cell to become cancerous. The cells that grow and divide the most are more likely to become cancerous because since they are constantly copying their DNA there are more opportunities for mistakes to happen.

      Mistakes happen all the time! But luckily our bodies have ways of proofreading DNA as it is being copied and fixing the mistakes as they happen. The mistakes have to be in certain areas otherwise they make no difference or just cause the cell to die. They have to be mistakes in the DNA that makes proteins involved in regulating the cell cycle, most significantly cell division.

      Another possibility is that the cell’s DNA is damages by an external source such as carcinogenic chemicals, UV light, or radiation.