This is important in the way that it also tells us about the complexity of the disease. So when someone develops cancer cells, those cells probably will develop a tumour – which means that there is an accumulation of cancer cells in a region. So it develops a kind of ball, imagine it like that – which means that cells divide themselves enough that you can, even in skin cells – skin cancers, for example, you can feel the tumour with your hand on your skin, and it’s going to be in that region.
Then this could be treated by the available treatments, could be surgery, could be combined with chemotherapy. So then we target those cancer cells and try to kill them as much as possible, but even with few cells left with the same mutation – they could reinitiate that process.
So this is why with the ‘all clear’ – of course, they monitor as much as they can. The tests available in medical settings now are trying to cover as much as they can. But, it’s not easy to say if there isn’t even one single cell left, because cancer cells could be metastatic – which means that they can migrate from one region through blood to another region in the body.
So, if one cancer cell makes it to the blood and then migrates, they can go and colonise another region or they can invade another region, and then they can continue dividing themselves there. Also, cancer cells are another fascinating side of the cancer, but also sad for the patient – of course, as they are quite responsive and dynamic, so when we treat them with something to kill them, they can dynamically reshape themselves – so then they can escape from that drug.
Of course, they are not going to do it the moment we are giving the drug for the first time, but then the ones that remained – if they find the way to escape from that effect of that drug, they might come back, and they might even be a bit stronger, because they probably now have developed resistance to that drug.
So, this is why we monitor those patients throughout their lives just in case, as it might reappear again. But this doesn’t mean that this will happen. There are many patients that are given all clear and don’t have it at all again. Also, there are some cases that you might see it’s coming back, and if you realise it in good time, you can still continue treating it and then get a positive outcome.
