Question: If radiation causes cancer how does it treat cancer?

  1. Fantastic question!
    The answer is essentially the same way, but its all about dose.
    All the cells in your body have 4 basic actions – grow, move, change or die. They perform these actions when the body tells them to using chemical signals called cytokines. Cytokines tell a cell to change the way the cell is using its DNA ( and when it does this it does one of those 4 actions I mentioned above.
    Radiation is a problem because it damages DNA. If DNA is damaged then the cell can’t respond to the cytokine, it becomes a rouge cell that doesn’t do what the body tells it to.
    It gets very complicated here but once a cell stops following instructions from the body it can start to misbehave very badly and we call a cell that stops doing thing the body tells it to do or worse, starts doing things its not supposed to, a cancer cell.
    The amount of radiation it takes to change DNA like this is comparable to sunburn and things like that.

    The idea behind using radiation to kill cancer cells is because if you damage the DNA a lot then the cell can’t recover and will die. The radiation here is much more powerful but much more targeted onto the cancerous cells only (where possible).

    As you can see, in both cases radiation causes DNA damage to change cells. A little damage to the DNA can sometimes result cancer but a lot will scramble the DNA enough that the cell will die.


  2. Hi mrbuttnose007 (??) Wow! Really great question. Radiation can have a lot of different effects on the body. Radiation can cause cancer because it damages our DNA. This means that the DNA can not do what it normally does, such as divide, make proteins, etc. It loses the ability to maintain normal function. For example, there are genes in our DNA that regulate how much/often a cell divides. If this genes is damaged and essentially “switched on” when it should be “switched off” then the cell will divide uncontrollably, leading to the development of a tumour. A tumour is essentially uncontrolled cellular growth. Radiation can be used as a therapy too (radiotherapy). If the tumour location is known, then a very strong, focussed beam of radiation can be delivered to that specific area of the body. This then damages the DNA so much that the cell dies.


  3. Hi mrbuttnose007

    This is a good question as it highlights an important point; there are many different sorts of radiation.

    Radiation is the word we use to describe the emission of energy. So light from the sun is radiation, as well as an X-Ray is a type of radiation.

    Some radiation can cause mutations in cells, which then go on to cause cancer. But we can also use certain types of radiation to kill cancerous cells, often very high energy radiation like gamma rays or x-rays. The radiation is used to damage the cancer cells and shrink down the tumor.

    While this sort of radiation can kill the cancer cells, it can also kill good cells. This is one of the side effects.

    This is a good question, here are two more links to further information if you are keen


  4. Hi mrbuttnose007!
    An excellent question! And nice username! 🙂
    There are many different types of radiation and these different types can affect our cells and DNA in different amounts/ways. Certain types (like UV rays) can damage our DNA, so then the affected cells which now have damaged DNA can no longer function properly. One of the things cells need to do regularly is divide a certain number of times (replicate) and then eventually they die as part of their natural life cycle. Things like this are controlled by DNA. Cells that can’t function properly anymore because of DNA damage can no longer control how much they replicate and so keep replicating – an out of control cell like this is what a cancer cell is.
    Some stronger types of radiation (like gamma rays) can cause so much damage to the DNA in cells that they will actually kill the cell. So if these types of stronger radiation are targeted at cancer cells, then they can be used to kill cancer (radiation therapy). If other healthy cells are hit by this radiation therapy then they will also die, which is why radiation therapy has to be targeted to the cancer cells as much as possible.
    So the amount and type of radiation exposure is important in whether cancer is caused or destroyed.
    Things other than radiation can also cause DNA damage and result in cancer or be used to cure cancer, like some chemicals. Some of the enzymes in the enzyme family my work is related to (Cytochromes P450) are also related to cancer and cancer causing chemicals (this type of chemicals are called ‘carcinogens’). Ask me a question if you’d like to know more about P450s and cancer. 🙂



  1. Nice one @James!