Steve Gale via Facebook asked:
I heard that radiation treatment for breast cancer can cause leukaemia. Is that true?
Chris - Yes, unfortunately it is true because the way in which some cancers are treated is with radiotherapy. Radiotherapy is a form of ionising radiation like x-rays, and as a result, when that ionising radiation goes through your body, it does damage cancer cells, and it tends to damage cancer cells more than healthy tissue because cancer cells are more vulnerable to damage because they don't have such good DNA repair mechanisms. But the point is, it can still damage healthy tissue.
And so, in the course of dealing with one tumour, it can increase the risk - it doesn’t necessarily give you cancer - but it can increase the risk of developing another type of cancer. Very often, bone can be targeted or bone marrow cells, and therefore, you can get secondary tumours developing later in life as a consequence of having been treated.
But if you take certain chemotherapy drugs, they don't necessarily have that same risk. They're not ionising radiation, so it depends on the kind of treatment that you get.