• Question: Why does cancer some back , when u have allready beat it?

    Asked by littlellie to Clare, Mariana, Pedro, Robert, Susanne on 16 Nov 2012.
    • Photo: Susanne Muekusch

      Susanne Muekusch answered on 16 Nov 2012:

      hi littlellie,

      The problem is, that you may have not completely destroyed all the cancer cells. Even if you can kill 99 percent of all cancer cells and you just have a few of them surviving, the cancer can come back. The remaining cancer cells can actually be quiet for years, before they start dividing and build a tumor again.

      Unfortunately, there is no way to tell, whether you killed all the cancer cells, or if there are still some left.

    • Photo: Clare Taylor

      Clare Taylor answered on 18 Nov 2012:

      @susanne is right. It is impossible for doctors to tell if all of the cancerous cells have been destroyed and there is always a small risk that the cancer will come back. That is why a doctor will never tell someone that they have been ‘cured’ of cancer. What a doctor is will usually say is that ‘there is no evidence of disease.’ It is also possible to get a different form of cancer than the first one. That is why so many scientists like us will keep on working to try and find new ways to try and prevent and treat cancer.

    • Photo: Mariana Campos

      Mariana Campos answered on 18 Nov 2012:

      As Susanne and Clare said, one cannot know if there are cancer cells left. We cannot see those cells, only if they start diving again and form a tumour again we see them.

    • Photo: Robert Insall

      Robert Insall answered on 18 Nov 2012:

      Dear Littlellie,
      It sounds like you know someone who has been treated for cancer and had it come back; I hope they’re OK.

      One of the problems with treating cancer is that the cells mutate. This means they change, so a drug that kills most cancer cells won’t kill the mutated ones. The trouble is, as Susanne and Clare have said, you have to kill ALL the cancer cells. If 99.9% of the cancer cells are killed, but 0.1% that have mutated aren’t killed, the 0.1% will grow up themselves and make new tumours.

      Worse, these tumours will be resistant to chemotherapy – the cancer cells that could be killed with drugs were killed the first time round. The only way to treat cancer that came back is with a new set of drugs, which may not be as good as the first lot.

      We spend a lot of time researching new drugs and combinations of drugs to get over this problem, but cancer is a nasty and cunning disease…

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