I have already said that any cell can be killed by radiation, provided the dose is high enough. So, what is it that prevents us from using radiation to cure all people with cancer?
The first problem is that radiation (with a few exceptions which I will mention later) is, like surgery, a local form of treatment. Only known cancer deposits, or areas that are very likely to be involved, are treated. This means that any undetected groups of cancer cells lying outside the irradiated area escape treatment. The treatment then cannot cure the patient, not because it fails to kill the treated cells, but because some cells are not treated at all. It is exactly the same sort of problem as we have with surgery that is aimed at cure. Careful assessment reduces the chance of some cancer escaping untreated. However, as you know, there are no tests that are capable of picking up very tiny groups of cancer cells. This means that even the most careful search for secondaries followed by a course of treatment which kills every cancer cell in the treated area cannot be guaranteed to produce a complete and permanent cure.
*260/40/1*
